Reverse Thrust Procedure

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The reverse thrust levers are clearly visible in the stowed position.  OEM throttle quadrant converted for flight simulator use

Pilots tend to be numbers-orientated individuals.  They like concise instructions and do not like ambiguity.  Nor do they like being presented with something that is in ‘shades of grey’ rather than ‘black and white’. 

When, how, and for how long to deploy the reverse thrust (reversers) falls into the 'grey area'.

In this article, I will endeavour to unravel some of the uncertainties as to when and how to use reverse thrust.  I will also briefly discuss the relationship between the use of the autobrake and reverse thrust.

I am not going to delve deeply into every environmental consideration that needs to be analysed prior to the use of reverse thrust; this information is more than readily available from the Flight Crew Operations Manual (FCOM), Flight Crew Training Manual (FCTM) and other specific airline policy documentation.

Reverse Thrust Basics

Reverse thrust (reversers) is used only for ground operations and is used after touchdown to slow the aircraft;  it is used to reduce the stopping distance, minimise brake temperatures and decrease wear and tear.

Reverse thrust comprises four détentes and an interlock position, that are engaged by moving the thrust levers from the stowed down position through to the fully up position.  

  1. No reverse thrust (thrust levers are closed / stowed position).

  2. Detent 1 (idle reverse / thrust levers are at first position).

  3. Detent 2 (thrust levers are at second position).

  4. Full maximum reverse thrust (thrust levers are at fully upward position).

Between detent 1 and full maximum reverse thrust there is scope for the thrust levers to be positioned part way; thereby, altering the amount of thrust generated.

Schematic showing various positions for the thrust reverser levers

The interlock mechanism is felt when the reverse thrust levers are advanced to detent 1. The purpose of the interlock is to restrict movement of the reverse thrust lever until the reverser sleeves have approached the deployed position.

The procedure to use reverse thrust is very straightforward, however, questions arise as to whether to use detent 2 or full maximum reverse thrust, and when to begin reducing thrust and for how long.

Procedure

Following touchdown, without delay, move the reverse thrust levers to the interlock position and hold light pressure until the interlocks release (as the sleeves move rearwards).

For most landings, detent 1 and detent 2 will usually provide adequate reverse thrust (for normal operations).  If additional reverse thrust is needed (wet, slippery or short field landing), full maximum reverse thrust can be selected by raising the thrust levers past detent 2 to full maximum reverse thrust.  

To come out of reverse, the reverse thrust levers are returned to the detent 1 position, the engine allowed to spool down, and the levers then returned to the stow position.

Practically speaking, after touchdown maintain reverse thrust as required up to maximum thrust until the airspeed approaches 60 knots. Reverse thrust is then slowly reduced to detent 1 and then to reverse idle by taxi speed. Wait until the generated reverse thrust has bleed off, then slowly close the reversers and place them in the stow position.

Bringing the reverse thrust levers to detent 1 is important because it prevents engine exhaust re-ingestion and minimises the risk of foreign object debris (FOD) ingestion.  Idle thrust also bleeds off forward thrust from the engines.

The autobrake is disarmed when a safe stop of the aircraft is assured, or when the aircraft reaches taxi speed.

Important Point:

  • If transitioning from using the autobrake to manual braking, use reverse thrust as required until reaching taxi speed and then disarm the autobrake.  

Disarming the autobrake before closing reverse thrust provides a relativity seamless transition which increases passenger comfort (there is no aircraft jolt).

Conditions Required To Engage Reverse Thrust

The reversers can be deployed when either of the following conditions occur:

  1. The radio altimeter senses less than 10 feet altitude;

  2. When the air/ground sensor is in ground mode; and,

  3. When the forward thrust levers are in the idle position.

Until these conditions occur, the movement of the reverse thrust levers is mechanically restricted and the levers cannot be moved into the aft position.

It is important to always deploy reverse thrust as soon as possible following touchdown.  Do not wait for the nose wheel to touch down, but engage reverse thrust when the main wheels are on the runway.  Timely deployment will increase stopping power; thereby, increasing safety and reducing heat build-up in the brake system.  

A study determined that there was roughly a 17 second difference in stopping time when reverse thrust was deployed immediately the landing gear was on the runway as opposed to waiting several seconds for the nose gear to also be on the runway - reverse thrust is most effectual at high airspeeds and its effect decays on a linear scale as forward airspeed decreases.

Important Points:

  • Reverse thrust should always be used with the autobrake, unless the runway is exceptionally long without a possibility of runway overrun (the reason for this will be explained shortly).

  • When closing the reversers, always pause at detent 1.  Monitor the REV thrust output on the Primary Engine Display (center panel) and stow the reversers only after reverse thrust has dissipated.

Call-outs

The pilot monitoring usually makes the following call-outs:

  • ‘60 knots’;

  • ‘Reversers normal’ -  when both REV indications are green;

  • ‘No reverser engine No: 1’ - if no REV indication or colour is amber; or,

  • ‘No reverser engine No: 2’ -  if no REV indication or colour is amber; or,

  • ‘No reversers’ -  if no REV indications or colour is amber.

NOTE:  Annunciators and displays are discussed later in the article.

During landing, the pilot monitoring (PM) should call out 60 knots to advise the pilot flying (PF) in scheduling the reduction of reverse thrust.  

When landings are in conditions that are suboptimal (heavy rain, snow, slush, etc), some operators stipulate that the PM operate and control the reverse thrust .  This enables the PF to concentrate solely on the landing roll out rather than having the extra responsibility of also controlling the reverse thrust.  

This said, although this procedure may lower pilot workload, it can cause problems when the PF is landing on a slippery runway or in marginal crosswind conditions.   At these times, the PF may wish to use the reverse thrust in conjunction with the brakes and there is little time to call out instructions to the PM.

Technical Aspects (basic operation)

Each engine on the Boeing 737 Next Generation is equipped with an hydraulically operated thrust reverser, consisting of left and right translating (moving) sleeves.  Aft movement of the reverser sleeves cause blocker doors to deflect fan discharge air forward, through fixed cascade vanes, producing reverse thrust.  

Hydraulic pressure for the operation of the thrust reversers comes from hydraulic systems A and B, respectively.  If hydraulic system A and/or B fails, alternate operation for the affected thrust reverser is available through the standby hydraulic system.  When the standby hydraulic system is used, the affected thrust reverser deploys and retracts at a slower rate and some thrust symmetry can be anticipated.

When reverse thrust is selected an electro-mechanical lock is released.  This causes the  isolation valve to open which results in the thrust reverser control valve moving to the deploy position, allowing hydraulic pressure to unlock and deploy the reverser system.

The system is designed in such a way that an interlock mechanism restricts movement of the reverse thrust lever until the reverser sleeves are in the deployed position.

Closing the thrust levers past detent 1 to the stow position initiates the command to stow the reverser.  When the lever reaches the full down position, the control valve moves to the stow position allowing hydraulic pressure to stow and lock the reverser sleeves.  After the thrust reverser is stowed, the isolation valve closes and the electro-mechanical lock engages.

Relationship with Flaps

There is an interesting relationship between the use of reverse thrust and flaps 40.

When the aircraft has flaps 40 extended, the drag is greater requiring a higher %N1 to maintain airspeed. This higher N1 takes longer to spool down when the thrust levers are brought to idle during the flare; this enables more energy to be initially transferred to reverse thrust.

Therefore, during a flaps 40 landing more energy is available to be directed to reverse thrust, as opposed to a flaps 30 landing.

Annunciators and Displays

Thrust reverse indicators are displayed in the Primary Engine Display located in the center panel slightly above the No: 1 and No: 2 %N1 indicators.  When reverse thrust is commanded, REV will be displayed initially in amber followed by green dependent upon the position of the thrust reverse levers.

  • Amber:  Thrust reverser has been deployed from the stowed position and both sleeves have travelled ~10-90% to the deployed position.

  • Green:  Thrust reverser has been deployed from the stowed position and both sleeves have travelled greater than 90% to the deployed position.

When either reverser sleeve moves from the stowed position, the amber REV indication annunciator, located on the upper display will illuminate.  As the thrust reverser reaches the deployed position, the REV indication illuminates green and the reverse thrust lever can be raised to detent 2.  

Electronic Engine Control (EEC) panel (AFT overhead). ProSim737 avionics suite virtual display

Additional reverse thrust annunciators are located on the aft overhead panel in the Electronic Engine Control (ECC) panel.  These annunciators are triggered by the retraction of the reverse thrust levers to the stow position.   

The annunciators will illuminate during a normal reverse thrust / stow operation for 10 seconds and then extinguish 10 seconds later when the isolation valve closes.  

A system malfunction has occurred if the reverser (REV) annunciator illuminates at any other time, or illuminates for more than approximately 12 seconds (in the later instance, the master caution and ENG system annunciator will also illuminate).

Possible reasons for a system malfunction are that the isolation valve, thrust reverser control valve, or one or both of the thrust reverser sleeves are not in their correct position.

Autobrake and Reverse Thrust Use (the grey area)

Both the autobrake and timely application of reverse thrust can be used to slow the aircraft, however, both come at a cost.  

Using the autobrake generates considerable heat in the braking system, translating to increased expenditure in maintenance and possible delays in turn around times (waiting for brakes to cool to operational temperature).  Conversely, reverse thrust consumes excess fuel.  Clearly there is a middle point where each will cancel out the other.

The immediate initiation of reverse thrust at main gear touchdown, and use of maximum reverse thrust, enable the autobrake system to reduce brake pressure to the minimum level – this is because the autobrake system senses deceleration and modulates brake pressure accordingly.  Therefore, the proper application of reverse thrust results in reduced braking and less heat generation for a large portion of the landing roll.

Based on this premise, it stands to reason that this is why Boeing recommend to use the autobrake in conjunction with reverse thrust.

Boeing states in the FCTM that: ‘After touchdown, with the thrust levers at idle, rapidly raise the reverse thrust levers up and aft to the interlock position, then to reverse thrust detent 2.  Conditions permitting, limit reverse thrust to detent 2’.

It appears to be Boeing’s intention to use reverse thrust as the major force to stop the aircraft, and as the use of maximum reverse thrust further minimises brake system heating, it would appear to be a preferred choice, despite the FCTM stating detent 2 is the preferred position for normal operations.

The official literature does not satisfactorily address this ‘grey area’   The result being that many 737 pilots use differing techniques when deploying and stowing the reversers.

Various Methods

If you observe how other pilots use the reversers, you will discover that there are several variations that follow the same theme.

1.    A pilot will, when the aircraft passes through 60 knots, close reverse thrust by lowering the reverse thrust levers through detent 1 to the stow position without stopping at detent 1;

2.    Try to locate detent 1 by ‘feel’ resulting in pushing the levers too far towards the stow position, causing forward thrust to unexpectedly occur momentarily;

3.    Deliberately close maximum reverse thrust at the 60 knots by placing the reverse thrust levers into the stow position.

In the above three scenarios, the reverse thrust levers have not been allowed to pause at  the detent 1 position.  Pausing at detent 1 is important as %N1 requires several seconds to reduce to idle thrust after maximum reverse thrust has been used, and it is during this ‘wind down’ period, as the reverse sleeves fully close, that %N1 will transition through 55-60%N1, which is forward thrust.  

By not allowing the reversers to pause momentarily at detent 1, to enable thrust to disparate below 55-60%N1, may cause the aircraft to momentarily accelerate.  This can be rather disconcerting, especially on a short field landing or landing in marginal conditions.

So What Do I do (normal procedure)

  1. At touchdown I engage reverse thrust – either detent 2 or maximum reverse thrust (or part thereof).

  2. Approaching 60 knots I slowly and smoothly retard the reverse thrust levers to detent 1.

  3. I always allow a few seconds at detent 1 to enable %N1 to dissipate.

  4.  Approaching taxi speed I disarm the speedbrake and close the reversers.

  • At no time do, unless in an emergency, do I close the reversers suddenly; I always close the reversers smoothly and slowly. This enables %N1 to dissipate gradually.

Final Call

The procedure to deploy reverse thrust is straightforward and very easy to accomplish, and there is little argument that reverse thrust should be used on all, but the longest runways in optimal environmental conditions.   However, there is confusion and often disagreement to when the reversers are deployed, whether maximum reverse thrust should be used, and for how long the reversers should be left in the open position before retraction and stowing.

It is unfortunate that the information written in the Flight Crew Training Manual (FCTM) and Flight Crew Operations Manual (FCOM) does not provide a more objective ‘black and white’ answer to this procedural dilemma.

Video

The below video shows the REV indicators on the Primary Engine Display (when reverse thrust is commanded) and the REVERSE annunciators on the ECC panel (AFT overhead).  Video taken directly from ProSim-AR 737 avionics suite (virtual software).  Video upload to U-Tube rather than VIMEO).

 
 

Conversion of OEM CDU - Part Two

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OEM CDU operational with ProSim737

In this second article, I will explain how the OEM Control Device Unit (CDU) was converted to enable a SimStack Foundation Board to be installed inside the unit and connected to ProSim737. 

SimStacks are manufactured by Simulator Solutions, which is a Sydney based company in Australia and their foundation boards can be used with ProSim737 and ProSim320 avionics suites. 

This is but one method to convert an OEM item to be used with flight simulator.

This article will mainly address the mechanical conversion of the CDU.  A future article, after flight testing,  will provide a review of SimStacks interface cards.

Conversion

Many of the OEM parts used in the simulator have been converted using Phidget cards, and to a lesser extent Leo Bodnar and PoKeys interface cards.  Phidgets provide a stable platform, despite the disadvantage that they, at time of writing, can only connect via USB to the server computer, and don’t enable every OEM function to be used in ProSim-AR.  The primary advantage of using Phidgets is that they have been used in a wide variety of applications, are inherently stable, and their configuration is well documented.

I decided that, rather than use Phidgets, a different system would be trailed to interface the CDU with ProSim737. 

he SimStack Foundation Board mounted on an angular bracket inside the CDU.  Fortunately there is ample room to mount the board inside the CDU

SimStacks by Simulator Solutions

The conversion of the CDU was done in collaboration with Sydney-based company Simulator Solutions Pty Ltd.  Simulator Solutions use their propriety interface boards called SimStacks to convert OEM parts for use in commercial-grade simulators.

SimStacks is a modular, stackable, and scalable hardware interface that is designed to integrate OEM parts into your simulator with little or no modification.    One of the many advantages in using a SimStack board is that the interface can connect with either the server or client computer via Ethernet (as opposed to Phidgets). 

To date, Simulator Solution’s experience has been predominately with the conversion of B747 parts and Rodney and John (owners) were excited to have the opportunity to evaluate their software on the 737 platform using ProSim737. 

Converting the CDU - Choose Your Poison

There are two main camps when discussing how to convert an OEM part.  The first is to use as much of the original wiring and parts as possible.  The second is to completely ‘gut’ the part and convert it cleanly using an interface that connects seamlessly with the avionics software in use (ProSim-AR).  A third option, although expensive and in many respects ‘experimental’, is to use ARINC 429. 

ARINC 429 is a protocol used in real aircraft to enable panels etc to be connected with the aircraft’s systems, and although it can be used in a simulated environment, it’s not without its shortfalls, in particular, the use of AC power (in contrast to DC power).

To use SimStacks the internal components of the CDU had to be removed, with the  exception of the internal shelf divider and keypad.  In hindsight, the pin-outs of the Canon plugs could have been used, but in doing so a female Canon plug would have been required, and for the use of a couple of pins, the price of a Canon female plug was expensive.

Keypad and Screen

The keypad and screen are the two most important parts of the CDU. 

The keypad forms part of the lightplate.  The backlighting for the keypad is powered by 21 5 Volt incandescent bulbs, strategically located to ensure even backlighting of the keys.

table 1: provides an overview of bulb location, part number and quantity

Like anything, bulbs have a limited left and, although OEM bulbs are renown for their longevity, there is always a chance that some bulbs are broken.  In this case, there were 3 bulbs that needed replacement.

Disassembling and removing the keypad from the main body of the CDU is straightforward; several small Philips head screws hold the keypad in place.  Once the keypad has been removed, any ‘blown’ bulbs can be replaced. 

The most important area is the keypad is what is called the terminus (bus).  Several wires from the keypad travel to the bus and then to the various (now removed) parts in the CDU.  The Simstack Foundation Board is wired to the bus, therefore, care must be taken to not damage these wires between the bus and the keypad. 

737 CL CDU showing older green coloured text displayed on CRT screen

I found that the wires were quite short and needed to be lengthened; this can be done by splicing longer wire to the existing wire.  Although it's possible to replace the wire to the keypad, this would entail re soldering the wires to the various keypad points - a process that requires very exact soldering.

CRT screen showing thick curved glass

CRT and LCD Screen

The Classic CDU from airframes up to the Boeing 737-500 is fitted with a solid glass cathode ray tube (CRT) screen. 

The CRT screen is approximately 2 cm thick, curved in design, and fits snugly within the display frame of the CDU.  Although it’s possible to make this screen operational, the display will be mono-colour (green) and the screen resolution poor.  Therefore, the CRT was replaced with a custom-sized high resolution colour LCD screen.

To replace the CRT screen is not without its challenges.  The first being that the LCD screen is not 2 cm in thickness and will not fit snugly within the curved display recess of the CDU frame.  To rectify this shortfall, a piece of clear glass must be ground to correctly fit within the frame.  This piece of glass replaces the 2 cm thick, curved CRT glass.

Photo showing how the thin LCD screen was secured with tape the glass screen.  Although the process appears rudimentary, it's functional

The thin LCD screen is installed directly behind the clear glass using high density tape.  Commercial grade double-sided sticky tape is the easiest method, but it is rudimentary.  The reason that tape is used, is that should the screen fail, it’s easy to remove the tape, install a replacement screen, and then tape the screen in place.

During the design phase, it was thought that the thick piece of glass would cause a refraction problem.  However, although the theory suggests refraction will occur, the practical application has been such that any refraction is not readily noticeable.

Installing the SimStacks Foundation Board and Screen Controller Card

To enable the CDU to operate, four items need to be mounted inside the CDU.

(i)   The generic Interface card that controls the LCD screen;

(ii)   The LCD screen controller (buttons that control brightness, contrast, etc);

(iii)  The SimStack Foundation Board; and,

(iv)  The wiring to connect the keyboard to the Foundation Board.

Fortunately, there is ample room in the cavernous interior of the CDU to fit these items. 

The SimStack Foundation Board is mounted on an angular metal bracket that is attached directly to the bottom of the CDU, while the LCD interface card has been installed on the upper shelf along with the screen controller.  A ribbon cable connects the LCD screen to the interface card while a standard VGA cable connects the LCD screen to the client computer and Ethernet switch. 

The SimStack Foundation Board is Ethernet ready and requires a standard Ethernet cable (CAT 6) to connect from the card to an Ethernet switch (located behind the MIP).  In addition to the Ethernet  and VGA cable, six power wires leave the CDU via the rear of the casing; four from the SimStack Foundation Board (5 and 12 volts +-) and two from the keypad (5 volts +-) to control the backlighting.

The specialist switch and wiring (Ethernet, power and VGA cables) extruding from the rear of the CDU

Specialist Switch and Power Supply

A standard two-way toggle switch is mounted to the rear of the CDU casing. 

This switch is used to control whether the LCD screen, used in the CDU, is always on, or is only turned on when ProSim-AR is activated.

To operate the CDU requires a 5 and 12 volt power supply.  The backlighting of the keypad is powered by 5 volts while the SimStack Foundation Board and CDU operation require 12 volts.

Backlight Dimming (keypad)

To enable the CDU keypad to be dimmed, the 5 volt wires are connected to a dedicated 5 volt Busbar located in the center pedestal.  This Busbar is used to connect the backlighting from all OEM panels.  The Busbar is then connected to the panel knob on the center pedestal.  The ability to turn the backlighting on and off is controlled by opening or closing a 12 volt relay (attached in line between the panel knob and Busbar).  Dimming is controlled by a dimmer circuit (see earlier article).

Installing the OEM CDU to Flight Deck Solutions MIP

It can be challenging attempting to install OEM panels, gauges and other items to a reproduction Main Instrument Panel (MIP).  Unfortunately, no matter what the manufacturer states, many MIPS do not comply with real world measurements.  

Before and after photograph of the FDS CDU bay showing the small flange from the shelf that needed to be trimmed to enable the CDU to slide into the bay recess.  A small notch was made at the corner to facilitate the safe routing of the wires used to enable the Lights Test

The MIP skeleton is manufactured by Flight Deck Solutions (FDS) and the CDU bay, although fitted with OEM DZUS rails, is designed to fit FDS’s propriety CDU unit (MX Pro) and not an OEM unit. 

The casing for the OEM CDU is much longer than the FDS CDU and measures 20 cm in length.

The FDS MIP design is such that the aluminum shelf (used by FDS to mount various interface cards) protrudes slightly into the rear of the CDU bay.  This protrusion stops the OEM casing from sliding neatly into the bay to its fullest extent.  To enable the CDU to slide into the CDU bay, the shelf must be ‘trimmed’.

To trim the metal away from the shelf, a small metal saw was used, and although an easy task, care must be taken not to ‘saw away’ too much metal.  Once the piece of offending aluminum is removed, the CDU slides perfectly into the bay, to be secured by DZUS fasteners to the DZUS rail.

Functionality and Operation

The CDU is not intelligent; it’s basically a glorified keyboard that must be interfaced with ProSim-AR to enable the CDU to function correctly.  The fonts and colour of the fonts is generated by the avionics suite (in this case ProSim-AR, but arguably it could also be Sim Avionics or Project Magenta). 

To enable communication between the avionics suite and the SimStack Foundation Board, proprietary software must be installed.  This software has been developed by Simulator Solutions.

SimStack Software (simswitch)

Screen grab showing SimSwitch software User Interface.  SimSwitch is standalone once the initial configuration has been completed.  The software can be configured to open in minimised mode via a batch file

To enable communication between the Foundation Board and ProSim737, propriety software, called SimSwitch must be installed to the computer that has the CDU connected. 

SimSwitch is a JAR executable file, that when configured with the correct static IP address and port numbers, provides communication between ProSim-AR (on the server computer) and the network (clients).  The switch must be opened for communication to occur between the Foundation Board, SimSwitch and ProSim737.  The jar file can easily be included into a batch file (with timer command) for automatic loading when flight simulator is used.

When opened, SimSwitch displays the User Interface.  The User Interface displays all OEM panels that have been connected using a SimStacks, can be used to monitor connected panels, and can display debugging information (if required).

Independent Operation

The Captain and First Officer CDUs are not cloned (although this is easy to do), but operate as separate units.  This is identical to the operation in the real aircraft, whereby the Captain and First Officer are responsible for specific tasks when inputting the information into the CDU.

First Officer CDU

The First Officer CDU will be converted using a similar technique, with the exception that this unit will be converted more ‘cleanly’.  Rather than use an angled plate on which to attach the SimStacks Foundation Board, a solid aluminum plate will be used.  The LCD screen controller card will also be attached to the rear of the LCD screen.  Finally, to enable fast and easy removal of the CDU, the connection of the Ethernet cable will be outside of the unit.

Additional Information

SoarByWire (another enthusiast) has written an excellent article dealing with interfacing SimStacks.

Below is a short video demonstrating the operation of the OEM CDU using ProSim737.

Main points to note in the video are:

  • Heavy duty tactile keys.

  • The definite click that is heard when depressing a key.

  • The solid keypad (the keys do not wobble about in their sockets).

  • Although subjective, the appearance of the OEM CDU looks more aesthetically pleasing that a reproduction unit.

 
 

Final Call

The conversion has been successful and, when connected with ProSim737 via SimSwitch, all the functions available in the CDU work correctly.

Glossary

  • ARINC 429 –  A standard used to  address data communications between avionics components.  The most widely used  standard is an avionics data bus.  ARINC 429 enables a single transmitter to communicate data to up to 20 receivers over a single bus.

  • Standalone – Two meanings.  Operation does not require an interface card to be mounted outside of the panel/part; and, In relation to software, the executable file (.exe) does not need to be installed to C Drive, but can be executed from any folder or the desktop.

  • Updated for clarity and information 12 June 2020.

How To Calibrate Flight Controls in Flight Simulator Using FSX, Prepar3D or FSUIPC

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Imagine for a brief moment that you are driving an automobile with a wheel alignment problem; the vehicle will want to travel in the direction of the misalignment causing undue stress on the steering components, excessive tyre wear, and frustration to the driver. 

Similarly, if the main flight controls are not accurately calibrated; roll and pitch will not be correctly simulated causing flight directional problems, frustration and loss of enjoyment.

Flight controls are usually assigned and calibrated in a two-step process, first in Windows, then either by using the internal calibration provided in the FSX, Prepar3D, ProSim737, or using the functionality provided by FSUIPC.

It's often easier to think of calibrating controls as a two-stage process - Primary Calibration (in Windows) and Secondary Calibration (in Prosim737, flight simulator, or FSUIPC).

In this post, the method used to assign and calibrate the main flight controls (ailerons, elevators and rudder pedals) in FSX, Prepar3D and FSUIPC will be discussed.  Internal calibration in ProSim737 will not be discussed.  The common theme will be the calibration of the ailerons, although these methods can calibrate other controls. The calibration of the throttle unit will not be discussed.

Many readers have their controls tweaked to the tenth degree and are pleased with the results, however, there are 'newcomers' that lack this knowledge.  I hope this post will guide them in the 'right direction'.

STEP 1 - Calibrating and Registering Control Devices in Windows (Primary Calibration)

All flight controls use a joystick controller card or drivers to connect to the computer.   This card must be registered and correctly set-up within the Windows operating system before calibration can commence.  

  • Type ‘joy’ into the search bar of the computer to open the ‘game controllers set-up menu’ (set-up USB game controllers).  This menu will indicate the joystick controller cards that are attached to the computer (Figure 1). 

  • Scroll through the list of cards and select the correct card for the flight control device.  Another menu screen will open when the appropriate card is selected.  In this menu, you can visually observe the movements of the yoke, rudder pedals and any yoke buttons that are available for assignment and use.  The movement of the controls will be converted to either a X, Y or Z axis (Figure 1).

  • Follow the on-screen instructions, which usually request that you move the yoke in a circular motion, stopping at various intervals to depress any available button on the device.  The same process is completed for the movement of the control column (forward and aft) and the rudder pedals (left and right).  Once completed, click ‘save’ and the profile will be saved as an .ini file in Windows.

 

FIGURE 1:  Windows Joystick Calibration User Interface or Game Controller Interface in (Primary Calibration of joystick controllers)

 

Registration is a relatively straightforward process, and once completed does not have to be repeated, unless you either change or reinstall the operating system, or recover from a major computer crash, which may have corrupted or deleted the joystick controller’s .ini file. 

STEP 2 - Assigning Flight Control Functionality in FSX and Prepar3D (Secondary Calibration)

  • Open FSX or Prepar3D and select from the menu ‘Options/Settings/Controls’.  The calibration, button key and control axis tab will open (Figure 2).

  • Select the ‘Control Axis’ tab. When the tab opens, two display boxes are shown.  The upper box displays the joystick controller cards connected to the computer while the larger lower box displays the various functions that can be assigned.  The functions that need to be assigned are ailerons, elevators and rudders.

  • Select/highlight the appropriate entry (i.e. ailerons) from the list and click the ‘Change Assignment’ tab.  This will open the ‘change assignment’ tab (Figure 3).  Physically move the yoke left and right to its furthest extent of travel and the correct axis will be assigned.  To save the setting, click the ‘OK’ button. 

  • When you re-open the ‘Control Axis’ tab you will observe that the function now has an axis assigned and this axis is identical to the axis assigned by Windows when the device was registered.  You will also note a small box labelled ‘Reverse’.  This box should be checked (ticked) if and when the movement of the controls is opposite to what is desired (Figure 3). 

  • Save the set-up by clicking the ‘OK’ button.

 

FIGURE 2:  FSX Settings and Controls Tab (Prepar3D menus are similar)

 
 

FIGURE 3:  FSX Change Assignment Menu

 

STEP 3 - Calibrating Flight Controls in FSX and Prepar3D

The flight control functions that have been assigned must now be calibrated to ensure accurate movement.   

  • First, select and open the ‘Calibration’ tab.  Ensure the box labelled Enable Controllers(s)’ is checked (ticked) (Figure 4).

  • The correct joystick controller card must be selected from the list displayed in the box beside the controller type label.

Whether simple or advanced controls are selected is a personal preference.  If advanced controls are selected, the various axis assignments will be shown in the display box.  The axis, sensitivity and null zone can be easily adjusted using the mouse for each of the flight controls (ailerons, elevators and rudders). 

Concerning the sensitivity and null zone settings.  Greater sensitivity causes the controls to respond more aggressively with minimal physical movement, while lesser sensitivity requires more movement to illicit a response.  It is best to experiment and select the setting that meets your requirement.

The null zone creates an area of zero movement around the centre of the axis.  This means that if you create, for example, a small null zone on the ailerons function, then you can move the yoke left and right for a short distance without any movement being registered. 

Creating a null zone can be a good idea if, when the flight controls are released, their ability to self-center is not the best.  Again, it is best to experiment with the setting.  To save the settings click the ‘OK’ button.  

 

FIGURE 4:  FSX Settings and Controls

 

This completes the essential requirements to calibrate the flight controls; however, calibration directly within FSX or Prepar3D is rather rudimentary, and if greater finesse/detail is required then it's recommended to use FSUIPC.  

FSUIPC

FSUIPC pronounced 'FUKPIC' is an acronym for Flight Simulator Universal Inter-Process Communication, a fancy term for a software interface that allows communication to be made within flight simulator.  The program, developed by Peter Dowson, is quite complex and can be downloaded from the website.  FSUIPC allows many things to be accomplished in flight simulator; however, this discussion of FSUIPC, will relate only to the assigning and calibrating of the flight controls.

It's VERY important that if FSUIPC is used, the FSX or Prepar3D ‘Enable Controllers’ box must be unchecked (not ticked) and the joystick axis assignments, that are to be calibrated in FSX or Prepar3D be deleted.  Deleting the assignments in optional, however, recommended.  The flight controls will only function accurately with calibration from one source (FSX, Prepar3D or FSUIPC)

STEP 1 - Assigning Flight Controls Using FSUPIC

  • Open FSX or Prepar3D and from the upper menu on the main screen select Add Ons/FSUIPC’.  This will open the FSUIPC options and settings interface (Figure 5).

  • Navigate to the ‘Axis Assignment’ tab to open the menu to assign the flight controls to FSUIPC for direct calibration (Figure 6).

  • Move the flight controls to the full extent of their movement.  For example, turn the yoke left and right or push/pull the control column forward and aft to the end of their travel.  You will observe that FSUIPC registers the movement and shows this movement by a series of numbers that increase and decrease as you move the flight controls.  It will also allocate an axis letter.

  • At the left side of the menu (Figure 6) is a label ‘Type of Action Required’; ensure ‘Send Direct to FSUIPC Calibration’ is checked (ticked).  Open the display menu box directly beneath this and select/highlight the flight control functionality (ailerons, elevator or rudder pedals).  Check (tick) the box beside the function.

 

FIGURE 5:  FSUPIC Main Menu

 
 

FIGURE 6:  FSUIPC Axis Assignments

 
 
 

Calibrating Flight Controls Using FSUIPC

  • Select the Joystick Calibration’ tab.  This will open an 11 page menu in which you calibrate the flight controls in addition to other controls, such as multi-engine throttles, steering tiller, etc.  Select page 1/11 'main flight controls' (Figure 7)

  • Open the ‘Aileron, Elevator and Rudder Pedals’ tab (1 of 11 main flight controls).  Note beside the function name there are three boxes labelled ‘set’ that correspond to min, centre and max.  There is also a box labelled ‘rev’ (reverse) which can be checked (ticked) to reverse the directional movement of the axis should this be necessary.  The tab labelled ‘reset’ located immediately below the function name opens the calibration tool.  The ‘profile specific’ box is checked (ticked) when you want the calibration to only be for a specific aircraft; otherwise, the calibration will be for all aircraft (global).  The box labelled filter is used to remove spurious inputs if they are noted and for the most part should be left unchecked (not ticked).  The tab labelled ‘slope’ will be discussed shortly.

  • Click the ‘reset’ tab for the ailerons and open the calibration tool.  Move the yoke to the left hand down position to its furthest point of travel and click ‘set’ beneath max.  Release the yoke and allow it to center.  Next, move the yoke to the right hand down position to its furthest point of travel and click ‘set’ beneath min.  Release the yoke and allow it to center.  If a null zone is not required, click the ‘set’ beneath centre.

If a problem occurs during the calibration, the software will beep indicating the need to restart the calibration process.  The basic calibration of the yoke is now complete.  However, to achieve greater accuracy and finesse it is recommended to use null zones and slope functionality.

 

FIGURE 7:  FSUIPC Joystick Calibration (ailerons, elevator and rudder)

 

Null Zones

The null zone concept has been discussed earlier in this article.

If a null zone is required either side of the yoke center position, move the yoke to the left a short distance (1 cm works well) and click ‘set’ beneath centre.  Next, move the yoke 1 cm to the right and click ‘set’ beneath centre.  

As you move the yoke you will observe in the side box a series of numbers that increase and decrease; these numbers represent the movement of the potentiometer.  It is not important to understand the meaning of the numbers, or to match them.

Replicate the same procedure to calibrate the elevators and rudder pedals (and any other controller devices)

To save the setting to the FSUIPC.ini file click ‘OK’. 

It is a good idea to save the FSUIPC.ini file as if a problem occurs at a later date, the calibration file can easily be resurrected.  The FSUIPC.ini file is located in the modules folder that resides in the FSX or Prepar3D route folder.  

Slope Functionality

Slope functionality is identical to the sensitivity setting in FSX and Prepar3D.  Decreasing the slope (negative number) causes the controls to be more sensitive when moved, while a positive number reduces the sensitivity. To open the slope calibration, click the ‘slope’ tab.  This will open a display box with an angled line.  Manipulating the shape of this line will increase or decrease the sensitivity.

Slope functionality, like the null zone requires some experimentation to determine what setting is best.  Different flight controls have differing manufacturing variables, and manipulating the slope and null zone allows each unit to be finely tuned to specific user preferences.

Does FSUIPC make a Difference to the Accuracy of the Calibration ?

In a nutshell – yes.  Whilst the direct assignment and calibration in FSX and Prepar3D is good, it's only rudimentary.  FSUIPC enables the flight controls to be more finely adjusted equating to a more stable and predictable response to how the controls react.

Potential Problems

If using FSUIPC for axis assignment and calibration, remember to uncheck (not tick) the ‘enable controller’ box and delete the axis assignments in FSX or Prepar3D – only one program can calibrate and control the flight controls at any one time.  If calibration from both FSX or Prerpar3D and FSUIPC are used at the same time, spurious results will occur when the flight controls are used.

If the calibration accuracy of the flight controls is in doubt (spurious results), it is possible that the simulator software has inadvertently reassigned the axis assignments and enabled calibration.  

There's an intermittent issue in FSX and Prepar3D where the software occasionally enables the controllers and reassigns the axis assignment, despite these settings having been unchecked (not enabled).  If a problem presents itself, it's best to double check that this has not occurred.  This is why I recommend that the settings be deleted, rather than just being unchecked.

Final Call

Many enthusiasts are quick to blame the hardware, avionics suite, or aircraft package, when they find difficulty in being able to control the flight dynamics of their chosen aircraft.  More often than not, the problem has nothing to do with the software or hardware used, but more to do with the calibration of the hardware device.

The above steps demonstrate the basics of how to calibrate the flight controls - in particular the ailerons.  If care is taken and you are precise when it comes to fine-tuning the calibration, you maybe surprised that you are now able to control that 'unwanted pitch' during final approach.

Further Information and Reading

Documents relating to FSUIPC can be found in the modules folder in your root director of flight simulator on your computer.  The below link addresses how to calibrate the steering tiller.

Cost Index (CI) Explained

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Screengrab from CDU screen showing the Cost Index page in PERF INIT

The Cost Index (CI) function of the Flight Management Computer (FMC) is an important and often misunderstood feature of a modern airliner.  Apart from real-world cost savings in fuel, differing CI values alter airspeeds used during the climb, cruise and descent phase of a flight.  Certainly, the CI value is not a pressing issue for a virtual pilot flying a simulator, but to an operating airline in a fuel-expensive environment, differing CI values can equate to thousands of dollars saved.

CDU showing Cost Index.  A CI of 11 will generate significant savings as opposed to a value of 300.  FMC is produced by Flight Deck Solutions (FDS)

Simply explained, the CI alters the airspeed used for economy (ECON) climb, cruise and descent; it is the ratio of the time-related operating costs of the aircraft verses the cost of fuel.  If the CI is 0 the FMC calculates the airspeed for the maximum range and minimum trip fuel (lower airspeed).  Conversely, if the CI is set to the highest number, the FMC will calculate higher airspeeds (Vmo/Mmo) and disregard any cost savings.

In practice, neither of the extreme CI values is used; instead, many operators use values based on their specific cost structure, modified if necessary to the requirements of individual flight routes.  Therefore, the CI values will typically vary between airline operators, airframes, and individual routes.

Access to the CI is on page 1 of 2 in the ‘ACT PERF INIT’ page of the Control Display Unit (CDU) of the Flight Management Computer (FMC).  It is on the left hand side lower screen and displayed ‘COST INDEX’.  The range of the CI is 0-200 units in the Boeing 737 Classics and 0-500 units in the Next Generation airframes.

Fuel Verses Time and Money

There is a definite benefit to an airline’s fuel cost when the CI is used correctly.  Bill Roberson in his excellent article ‘Fuel Conservation Strategies: Cost Index Explained’ states the difference between a CI value of 45 verses a CI value of 12 for a B737-700 can be in the order of $1790 - $1971 USD depending upon the price of fuel; the time gained by selecting the higher CI value (CI-12) is in the area of +3 minutes.  Although these time savings appear minimal, bear in mind that airlines are charged by the minute that they remain at the gate.

Granted fuel savings are important, but so is an airline’s ability to consistently deliver on time, its passengers and cargo. It is a fine line between cost savings and time management, and often the CI will be changed before a flight to cater towards unscheduled delays, a change in routing, short or long haul flights, cost of fuel, aircraft weight, or favourable in-flight weather conditions (i.e. tailwind).

A higher CI value may be used by airlines that are more interested in expediency than fuel cost savings; the extra revenue and savings generated by an airline that consistently meets its schedule with less time spent at the gate may be equal to, or greater than any potential fuel savings.  Boeing realizes that as fuel costs increase, airlines are reticent to only expend what is absolutely necessary; therefore, Boeing works with its clients (airlines) to determine, based upon their operating style, the most appropriate CI value to use.

Changing CI on The Fly'

Although not standard practice, the CI value can be changed during the flight.  Any change in the CI will reflect on climb, descent and cruise speeds, which will be updated in the CDU and can be monitored via the 'progress' page of the CDU. 

 

Figure 1: compares the cost index values against climb, cruise, descent and recommended altitudes for the Boeing 757 air frame.  Although these figures do not relate to the Boeing 737-800 NG, they do provide an insight into the difference in calculated CI values for climb, cruise, descent and recommended altitude

 

Is the Cost Index Modelled in all Avionics Suites

The CI is modelled by the avionics suite, and whether it is functional depends on the suite used.  ProSim737 and Sim Avionics have the CI modelled and functional, as does Project Magenta (PM), Precision Manuals Development Group (PMDG) and I-Fly.  

Airline Cost Index Values

As stated above, the inputted CI value is variable and is rarely used at either of the extreme ranges.  The following airline list of B737-800 carriers is incomplete, but provides guidance to CI values typically used.  Note that the CI is variable and the values below may alter dependent upon airlines operations.  A more detailed list can be found on the AVSIM website (Thanks Dirk (ProSim737 forum) for the link).

  • Air Baltic CI – 28

  • Air Berlin CI – 30

  • Air France CI – 35

  • Air Malta CI – 25

  • Air New Zealand CI – 45

  • Austrian CI – 35

  • Fly GlobesSpan CI – 13-14

  • Fly Niki CI – 35

  • Hamburg International CI – 30

  • KLM CI – 15/30

  • Nord Star CI – 30

  • Norwegian CI – 15

  • QANTAS CI – 40

  • Ryanair CI – 30

  • SAS CI – 45-50

  • South African CI – 50

  • South West CI – 36

  • Thomson Airways CI – 9

  • Ukraine International Airlines CI – 28

  • WestJet CI – 20-25

The CI is an important feature of the avionics suite that should not be dismissed.  Whilst real-world fuel savings are not important during simulator flying, the altered airspeeds that a different CI value generates can have consequences for the distance able to be flown, climb, descent and cruise speeds.

Acronyms

  • CDU – Control Display Unit

  • CI – Cost Index

  • FMC – Flight Management Computer

  • Mmo – Maximum operating speed

  • Vmo – Maximum operating limit speed

Boeing Chart (Map) Lights - B737NG and Classic B737 Types

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Chart lights removed from a Boeing 737-800 NG airframe.  Colour, appearance and design is different to the the older style lights used in the classic airframes

Chart lights (also called map lights) are attached adjacent to the overhead panel and are used to illuminate, in particular, the chart holders attached to the yoke during night time operations. There are two lights, one on the Captain-side and the other on the First Officer-side.

The light from the unit can be focused from a wide angle to a narrow beam by twisting the focus ring at the front of the light.  Each light can also be swiveled and moved vertically to position the light beam in a particular place on the flight deck (for example, chart plates).

The switches (knobs) that turn the light on and off are located on the sidewalls of the Captain and First Officer side of the flight deck.  The light can be dimmed if necessary by rotating the knob.

The chart lights are mounted near each the eyebrow windows.

Chart light removed from a Boeing 737-400 airframe.  The light has a differing focus ring, appearance and colour to the NG style (click to enlarge).  I believe this style of chart light is also used on the B747 aircraft

Two Styles (Classic and NG)

To my knowledge, there are two styles of chart light that have been used in the Boeing 737. The fatter style used in the classic series airframes and the more slender style used in the in the Next Generation airframes.  I have little doubt that there may also be small differences between light manufacturers.

The main aesthetic difference between the older 737 classic airframe chart lights and the newer Next Generation style is that the older lights are squatter and a little fatter in shape; the Next Generation is longer, more slender-looking and has a smaller footprint.

Chart light showing reflector dish on inner side of end cap.  This style is the older light type used in the 737 classic airframes

Other differences are internal and relate to how the light is focused on the lens and the physical shape of the focus rung used to alter the angle of light coverage.

Ingenious Design

Both style lights have an ingenious design to allow the light to be focused.   Removing the rear plate of from the older style light reveals the inner side to be a circular reflector dish (see image) which evenly distributes the throw of light when the unit is set to wide angle. 

The newer Next Generation style lights use an aperture blade which either enlarges or contracts as the focus ring is turned.  This design is identical to how a camera aperture works.

Both styles can use either a 12 or 28 Volt bulb; the later will generate a brighter light.  Connection is direct to the power supply (12 or 28 Volt).  An interface card is not required.

The NG style chart light.  A blade aperture controls the amount of light that is reflected onto the thick lens glass

Original Equipment Manufacturer (OEM)

Put bluntly, you cannot achieve a more realistic end product than when using a real aviation part.  Genuine parts, although at times difficult to find, are built to last; if they can withstand the continue abuse of pilots in a flight deck then they are more than adequate for home simulation use. 

It's true that while some parts appear used with faded and missing paint, they can easily be cleaned up with a fresh coat of paint.  Personally, I prefer the worn-appearance.

B737-800 NG Flight Mode Annunciator (FMA)

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oem Flight Mode annunciator (737-800)

Automatic Flight System - Background

The Boeing 737-80 has a relatively sophisticated Automatic Flight System (AFS) consisting of the Autopilot Flight Director System (AFDS) and the Autothrottle (A/T).  



The Boeing 737-800 NG has a relatively sophisticated Automatic Flight System (AFS) consisting of the Autopilot Flight Director System (AFDS) and the Autothrottle (A/T).   The system is as follows:

  • The N1 target speeds and limits are defined by the Flight Management Computer (FMC) which commands airspeeds used by the A/T and AFDS;

  • The A/T and AFDS are operated from the AFDS Mode Control Panel (MCP), and the FMC from the Control Display Unit (CDU); 

  • The MCP provides coordinated control of the Autopilot (A/P), Flight Director (F/D), A/T and altitude alert functions; and,

  • The Flight Mode Annunciator (FMA), located on the Captain and First Officer side of the Primary Flight Display (PFD),  displays the mode status for the AFS.

If you read through the above slowly and carefully it actually does make sense; however, during in-flight operations it can be quite confusing to determine which system is engaged and controlling the aircraft at any particular time.

Reliance on MCP Annunciations

Without appropriate training, there can be a reliance on the various annunciations and lights displayed on the Mode Control Panel (MCP).  While some annunciations are straightforward and only illuminate when a function is on or off (such as the CMD button), others can be confusing, for example VNAV.

Do not reply on the MCP.  Always refer to the FMA to see what mode is controlling the aircraft.

Flight Mode Annunciator (FMA)

All Boeing aircraft are fitted with an FMA of some type and style.  The FMA on the Next Generation is located on the Captain and First Officer side Primary Flight Display, and is continuously displayed.  The FMA indicates what system is controlling the aircraft and what mode is operational.  All flight crews should observe the FMA to determine operational status of the aircraft and not rely on the annunciators on the MCP that may, or may not indicate a selected function.

The FMA is divided into three columns and two rows. The left column relates to the Autothrottle while the center and right hand column display roll and pitch modes respectively.  The two rows provide space for armed and selected annunciations to be displayed.  Selected modes that are operational are always coloured green while armed modes are coloured white. 

Below the two rows are the Autopilot Status alerts which are in larger green-coloured font, and the Control Wheel Steering (CWS) displays which are coloured yellow.  The Autopilot Status alerts are dependent upon whether a particular system has been installed into that aircraft.  For example, Integrated Approach Navigation (IAN), and various autoland capabilities.

When a change to a mode occurs (either by by a flight crew or by the Automatic Flight System), a mode change highlight symbol (green-coloured rectangle) is displayed around the changed mode annunciation.  The rectangle will be displayed for 10 seconds following the change in mode.

Unfortunately, not all avionics suites have the correct timing (10 seconds) and some displays the rectangle for only 2 seconds.  According to the Boeing manual the default time should be 10 seconds.

figure 1: common mode annunciations that the FMA can display.  FMA annunciations may differ between airframes depending upon the software installed to the aircraft (and avionics suite used in your simulation).  G, W and Y indicates the colour of the annunciation (green, white, or yellow). the pitch mode FOR column and CWS display are not populated. 

ERRATUM: ILS, SINGLE CH and IDLE HAVE NOT BEEN INCLUDED WHEN THEY SHOULD HAVE

Important Points:

  • An annunciation that is green-coloured indicates a selected mode.

  • An annunciation that is white-coloured indicates an armed mode.

  • If there is some confusion to what mode is currently flying the aircraft, the FMA should be what you look at - not the MCP.

Video

Boeing 737 ILS CAT IIIa Autoland PFD demonstrating FMA.

 
 

OEM Boeing 737 Stick Shaker - Interfacing and Operation

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OEM 737 stick shaker installed to Captain-side column.  The lower section of device is what vibrates

The stick shaker is standard on all Boeing series aircraft; the Next Generation having two units (Captain and First Officer) and the earlier classic series having one unit.  The stick shaker is mounted directly to the control column and is designed to vibrate if air speed degrades to stall speed.  The Stick shaker I am using is manufactured by a company in New York. It is powered by 28 Volts (27.5 Volts to be exact).  

Configuration

Configuration of the stick shaker is a relatively easy task.  The electrical cable from the device is connected to 28 Volts, or if this is not available 12 Volts;  12 Volts still produces enough power for the shaker to vibrate, although the intensity is not as great as if the unit was connected to 28 Volts. 

To allow Flight Simulator to connect to the stick shaker, a relay card is required such as a Phidget 0/4/4 relay card.  A USB cable then connects from the card to the computer.  The stick shaker will vibrate when variables that relate to low air speed are met.  The variables are determined by the flight avionics software (ProSim737 or Sim Avionics).

Phidget 0/0/4 relay card showing the main positive wire (red wire) cut with each end inserted into the correct terminals of the relay card

Interfacing and Wiring

The Phidget 0/0/4 relay card is mounted in-line between the 28 Volt power supply and the stick shaker.    Either of the two wires (+-) from the power supply can be cut to install the in-line relay; however, only one wire is cut; the other remaining unbroken from the power supply to the stick shaker.

The 0/0/4 relay card has four relays of which one is required.  Each relay has three terminals: normally open (NO), common (C) and normally closed (NC).  For the stick shaker the common and normally open terminals are used.

Carefully cut one of the two wires leading from the 28 Volt power supply.  Insert the wire coming directly from the power supply into the terminal marked common (1C, 2C, 3C or 4C).  The other end of the cut wire, which comes from the stick shaker is inserted into the terminal marked NO (normally open) of the same terminal.

If the wires have been inserted into the correct terminal of the relay card, the circuit will be complete only when the parameters established within the flight avionics software are valid.  At all other times the relay will break the circuit by not allowing the power to reach the stick shaker. If you have made a mistake, the stick shaker will vibrate continuously.

Protection

When connecting the stick shaker, it is a good idea to include a diode to protect your computer from any magnetic return signal should the relay fail.  A return signal to the computer may cause problems with the computer, and in it worse instance allow 28 volts to surge into the computer destroying your mother board. 

Positive and negative wires from the stick shaker enter the terminal block on the right.  A diode is placed on the corresponding end of the terminal block prior to the two wires running to the relay (not shown)

A high-end relay, such as a Phidget 0/0/4 relay should not fail, and if it does it should fail in the closed position.  However, if 'Murphy' or 'Sod' is your First Officer then it is better to be safe than sorry, so best install a diode.

A diode is an inexpensive and very simple device that behaves in a similar way to a black hole (astronomy).  In a black hole all matter is sucked into the hole and no matter, including light leaves the hole; it is one way trap.  A diode behaves in exactly the same way.  If a failure of the relay occurs, any power that is being transmitted through the wire from the stick shaker (28 volts) will enter the diode and be trapped.  No current will leave the diode.

Three 6 cm diodes.  The silver spirals indicate the positive side (red tape) while the opposite end is the negative (white tape).  Diodes come in an array of differing shapes, sizes and trapping capacities

The heavy duty diode should be placed in parallel between the stick shaker and the relay card.  It is best to try and place the diode as close to the stick shaker as possible.  Place the positive side of the diode (usually appropriately marked) on the positive side.  The other end of the diode place on the negative side.  If you use a terminal block it is very easy to connect a diode into the circuit (see photograph).

Incorrect Wiring

Do not become concerned if you have connected the wire to the wrong terminal - the stick shaker will not be destroyed.  It will be obvious if you have inserted the wires incorrectly, as the stick shaker will operate continuously as it has unbroken power.

I was debating to re-paint the stick shaker, however, decided to keep it as it is.  I like the used look rather than the pristine 'never been there' look.

Although the stick shaker is not essential, it’s often the smaller things and attention to detail which help bring the simulator to the next level.  I am using OEM control columns and adding a stick shaker enhances the immersion.

OEM and Reproduction

When an OEM stick shaker vibrates, especially when you are not expecting it, the vibrations startle you . The yoke vibrates and the noise of the vibrations is quite loud. In contrast, reproduction stick shakers generate lower vibrations and noise.

Acronyms 

  • OEM - Original Equipment Manufacture (real aviation parts)

BELOW:  A short video demonstrating the noise and vibration made to the control column and yoke by the stick shaker when approaching stall speed.

 
 

B737 Throttle Quadrant - Automated Thrust Lever Movement

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Autothrottle arming switch is a solenoid operated switch clearly identified on the main Instrument Panel (MCP).  The switch is linked to the IAS/MACH speed window (adjacent) and to two A/T disconnect buttons located either side of the throttle lever handles. cp flight pro mcp

In this final post dealing with the conversion of the 737-500 throttle quadrant. I will discuss the automation and movement of the throttle thrust levers and touch on some problems that occurred.  I will also briefly discuss the installation and use of potentiometers.  Part of this post will be repetitive as I briefly discussed automation in an earlier post.

Avoiding Confusion - Automation

To avoid confusion, automation refers only to the movement of the two throttle thrust levers in relation to the %N1 output.  These N1 limits and targets are provided by the Flight Management Computer (FMC) and normally are used by the Autopilot Flight Director System (AFDS) and the Auto Throttle (A/T) to maintain airspeed and/or thrust setting.  

Automation and Movement - Interface Cards

Automation is the use of CMD A or CMD B (autopilot) to control the %N1 outputs from the Autothrottle (logic), and motorization is the moving of the throttle levers in unison with %N1 output.  To achieve this seamlessly, two interface and one controller card are used.

Alpha Quadrant Cards (2):  Each  motor controller card has the automation logic programmed directly to the card (via propriety software).  One card controls Auto Pilot CMD A while the other card controls Autopilot CMD B.

Phidget Advanced Servo Card (2):  This card acts as an interface and bridge between the Alpha Quadrant cards and the flight simulator platform used.

The card does not provide movement for the throttle thrust levers; this is controlled by a Phidget Motor Controller card.

Leo Bodnar BUO 836 A Joystick Controller Card:  This card will register in Windows the movement of levers, buttons and switches on the TQ.  Calibration of this card is done first in Windows, then in Flight Simulator (FSX/P3D), FSUIPC or the avionics suite used; for example, ProSim737.

The interface cards are mounted forward of the MIP within the Throttle Interface Module (TIM) and are connected to the throttle unit by custom VGA straight-through cables and to the computer by a single USB cable.

Main Controller Cards

The controller card I have used is not a Phidget card but a specialist card often used in robotics (Alpha Quadrant card).  The software to program the card has been independently developed by a software engineer and does not utilize Phidgets.

The technology used in the controller card is very similar to that utilized by NASA to control their robotic landers used in the space industry.  The technology is also used to control robots used in the car industry and in other mass production streams.  One of the benefits of the card is that it utilizes a software chip (firmware) that can be easily upgraded, reprogrammed, or replaced.  

The Alpha Quadrant cards provide the logic to operate the throttle automation (the movement of the thrust levers) and act as a bridge between the two cards and the avionics suite.

Being able to program each card allows replication of real aircraft logic and systems.  Whenever possible, these systems and their logic have been faithfully reproduced.

oem throttle. toga switches clearly seen

CMD A/B Autopilot - Two Independent Systems

Most throttle units only use one motor controller card which controls either CMD A or CMD B; whichever autopilot you select is controlled by the same card.  

In the real aircraft to provide for redundancy, each auto pilot system is separate.  This redundancy has been duplicated by using two Alpha Quadrant controller cards, rather than a single card.  Each controller card has been independently programmed and wired to operate on a separate system.  Therefore, although only one CMD is operational at any one time, a completely separate second system is available if CMD A or B is selected on the MCP.

Synchronized or Independent Lever Motorization

Synchronization refers to whether the two throttle thrust levers, based upon separate engine %N1 outputs, move in unison with each other (together) or move independently.

In earlier Boeing aircraft, such as the 707, 727 and 737 classics, the levers were roughly synchronized; however, the Next Generation has as a computer-operated fuel control system which can minutely adjust the %N1 of each engine.  This advanced fuel management can be observed in a real aircraft whereby each throttle lever creeps forward or aft independent of the other lever.

Programming flight simulator to read separate %N1 outputs for each engine, and then extrapolating the data to allow two motors to move the throttle levers independently is possible; however, the outputs are often inaccurate (for varying reasons).  This inaccuracy can often be observed on reproduction throttle units that exhibit a gap between lever one and lever two when automating %N1 outputs.  

It was decided to maintain the older system and have both levers synchronized.  Although this is not replicating the Next Generation system, it does make calibration easier.  If in the future incremental thrust lever movement is required, it’s a matter of adding another 12 Volt motor to the front of the throttle bulkhead to power the second thrust lever.  

Autothrottle activation will advance both thrust levers in unison to the fmc calculated %N1 output

Be aware that although both thrust levers are synchronized, the throttle handles may still show a slight difference in position in relation to each other.  This is caused by the varying tension that needs to be maintained on the fan belt connecting the 12 Volt motor to the mechanical system beneath the thrust levers.

Another aspect to note is that the position of the thrust levers during automation is arbitrary and is a visual representation of the %N1 output; it may or may not reflect the exact position on the throttle arc that the thrust lever would be placed if moved manually (by hand with Autothrottle turned off).  

Although the throttle is automated, manual override (moving the thrust levers by hand) is possible at any time, provided the override is within the constraints of the aircraft logic (programmed into the Alpha Quadrant card), and that provided by the flight avionics (ProSim737).  

Power Requirements and Mechanics

To provide the power to move the throttle thrust levers, a 12 Volt motor previously used to power electric automobile windows, is mounted forward of the throttle bulkhead (see image at bottom of post).  Connected to the motor's pulley is a fan belt that connects to the main pulley located beneath the thrust levers.  To enable the thrust levers to move in unison, a slip clutch, which is part of the main pulley assembly, is used.  

Captain-side TO/GA button is clearly seen below lever handles.  The button at the end of the handle is the Autothrottle disconnect button

ProSim737 Limitations - TO/GA and Auto Throttle Override

Unfortunately, concerning automation the ProSim737 is deficient in two areas: TO/GA and A/T Override.

(A)  TO/GA

In the real aircraft, the flight crew advances the thrust levers to power 40%N1 (or to whatever the airline policy dictates), allows the engines to spool, and then pushes the TO/GA button/s.  Pressing TO/GA causes the throttle to go on-line and to be controlled by the AFDS logic.  The throttle levers then advance automatically to whatever %N1 the logic deems appropriate based on takeoff calculations.

As at the time of writing. If you're using ProSim737, this will NOT occur.  Rather, you will observe the thrust levers retard before they advance (assuming you have moved the thrust levers to %40 N1).  The reason for this is nothing to do with how the throttle is calibrated, FSUIPC or anything else.  ProSim737 software controls the %N1 outputs for the automation of the thrust levers and the developer of the software has not fine-tuned the calibration in the software to take into account real-world avionics logic.  This thread located on the ProSim737 forum provides additional information. 

I have not tested Sim Avionics, but have been told this issue doesn't occur in their avionics suite.

There are two workarounds:  Engage TO/GA from idle (hardly realistic) or push the thrust levers to around 80% N1, allow the engines to spool, then push TO/GA.  Anything less that around 80% N1 will cause the thrust levers to retard before advancing.

Latest ProSim737 release (V133)

The latest version of ProSim737 (V-133) has provided improvement to the above issue.  Throttles can now be advanced to ~60% N1 and TOGA engaged without the throttle levers retarding.  This is possible ONLY if you calibrate the throttle levers within ProSim and allow ProSim to control the throttle output logic.  if you calibrate within FSUIPC then the same issue will apply.

According to ProSim developers, this issue is probably related to the calibration of the ProSim servo output. When you press TO/GA, the current N1 is taken and calculated back to a throttle percentage. This throttle percentage, when combined with the servo calibration data from ProSim results in a servo output. The servo calibration at the moment only has 2 calibration points, which are 0 and 100%. This results in a linear behavior between the two points, while depending on the construction of the throttle, the relationship might be non-linear. This would require a multi point calibration which is hard to do at the moment, because a throttle does not have exact readouts of the current position, so it will be hard to calibrate a 50% point.

This may need improvement in the code to auto calibrate the throttle system.

It's hoped that future release of ProSim737 will rectify this issue.

(B) Autothrottle Manual Override

In the real aircraft, manual override is available to a flight crew and the thrust levers can be retarded with the Autothrottle engaged.  When the flight crew release pressure on the thrust levers the Autothrottle will take control again and return the thrust levers to the appropriate position on the throttle arc dependent upon the speed indicated in the speed window of the MCP.

ProSim737 will not temporarily disconnect (manual override) the Autothrottle.  

At the time of writing, there is no workaround to solve this.

Potentiometers

There are many types of potentiometers; the two types most commonly used in flight simulation are the linear and rotary types. Linear potentiometers are inexpensive, often have a +- percentage variance, are compact, have a minimal throw depending upon the size of the device, and are not immune to contaminates building up on their carbon track. 

The last point is worth mentioning, as it is wrongly assumed that a potentiometer will remain correctly calibrated for the life of the unit.  General wear and tear, dust, and other debris will accumulate on the potentiometer; any of which may cause calibration and accuracy problems.  Keeping the potentiometers free of dust is important.

Rotary potentiometers (which may have a string attached) are very accurate, are in a sealed case and have very minimum chance of contamination. They are also made too exacting standards, are larger in size, and are expensive.

To read further about potentiometers

QAMP secured to base of throttle unit.  Thumb screws are visible on each corner of the plate.  A possible add on modification to reduce the risk of dust contamination to the potentiometers is a plastic cover that fits over the plate (a lunch box)

Calibration of Potentiometers

The main method of calibrating the position of the thrust levers is by calibrating the potentiometer in Windows, then in FSX followed by fine tuning in FSUIPC (if needed).  

At the moment I am using linear potentiometers; therefore, at some stage cleaning or replacement may be required.   The 737 throttle quadrant is not cavernous and only certain sized potentiometers will fit into the unit; this combined with other parts and wiring means that the potentiometers are often inaccessible without removing other components.  

To allow speedier access to the potentiometers, a Quick Assess Mounting Plate was designed.

quick access mounting plate (QAMP). four linear potentiometers are mounted to the plate. Two grub screws secure the plate to the throttle chassis

Quick Access Mounting Plate (QAMP)

The potentiometers are mounted directly onto a custom-made aluminum plate that is attached to the inside of the throttle unit by solid thumb screws.   To access the plate, the side inspection cover of the throttle is removed (a few screws) followed by turning the thumb screws on the access plate.  This releases the plate.

A similar plate has been designed and constructed for use with the stand-by potentiometer that controls the flaps.  A more detailed picture of the QAMP can be seen here..

Below is a video showing the movement of the thrust levers with the autothrottle engaged recorded during a test flight. 

 
 

Teething Issues with the Throttle Conversion

It was envisaged that more problems would have surfaced than have occurred.  The major issues are outlined below:

(A) Trim Wheels

An early problem encountered was that the trim wheels when engaging generated considerable noise.  After checking through the system, it was discovered that the two-speed rotation of the trim wheels were causing the two nuts that hold each of the trim wheels in place to become loose.  This in turn caused the trim wheels to wobble  slightly generating undue noise.  

Solution:

Tighten the two nuts at the end of the rod that holds the two trim wheels in place.

(B) Flaps 5 Not Engaging

The problem with the flaps 5 micro-button has been discussed in an earlier post.  To summarize, when you moved the flaps lever to flaps 5 the correct flaps were not selected on the aircraft or registered on the PoKeys 55 interface card.  Several hours were spent checking connections, micro-buttons, wiring and the custom VGA cables that connect the flaps section of the quadrant to the appropiate interface module; the problem could not be discovered.  

Solution:

One of the two Belkin powered hubs located within the IMM had been replaced with another powered unit.  It appears the problem was that the replacement hub had too low a voltage, as a replacement with a higher voltage solved the problem.

(C) Throttle Thrust Levers Not Synchronizing (A/T on)

The two thrust levers of the quadrant did not synchronize when the Auto Throttle (A/T) was engaged; one lever would always be ahead or behind of the other.  At other times they would split apart (do the splits) when A/T was engaged.  

Solution:

The problem was easily solved by altering the tension on the slip clutch nut.  When the nut was  tightened, both levers moved together as one unit.  The secret was finding the appropriate torque.

(D) Throttle Thrust Levers Difficult To Move in Manual Mode (A/T Off)

The ability to move the thrust levers in manual mode (Autothrottle turned off) was not fluid and the levers occasionally snagged or were sticky when trying to move them.  

The fan belt is barely visible linking the pulley of the motor to the main pulley inside the quadrant

This is caused by the fan belt not moving smoothly through the groove of the pulley wheel.   The Autothrottle when engaged overrides any stickiness due to the power and torque of the Auto Throttle motor.

Solution:

Unfortunately, there isn’t a lot you can do to rectify this issue as it’s a by-product of using a mechanical system in which the fan belt is central to the consistent operation of the unit.  

The conundrum is that if you tighten the fan belt too much you will be unable to manually move the thrust levers as they will be exceptionally stiff and difficult to move (as you are pushing against the tension of the fan belt); however, if you loosen the fan belt too much, although the levers will move fluidly by hand, the fan belt may not have enough tension to move the levers when Auto throttle is engaged.  It’s a matter of compromise; selecting an appropriate in-between tension to allow acceptable manual and Autothrottle operation.

A more reliable method is to use a small gearbox, a simple slip clutch and a coupler to connect to the spur gear.  Another option is to use an electrical system.

Further thought needs to be done in this area before a decision is made to replace the fan belt system.  If a new system is incorporated, the change-out will be documented in a future post.

Conclusion

Despite some of the shortcomings to this conversion, in particular the mechanical fan belt system, the throttle unit shows a marked improvement on the earlier 300 series conversion. 

Since the project began there has been three throttle conversions, and wth each conversion has built upon knowledge learnt from earlier conversions.  Initially there was the 737-300 conversion in 2012, which was converted in a rudimentary way and only operated in manual mode.  This was followed by the conversion of the 737-500 throttle in 2016.  This throttle was then rebuilt and upgraded in 2017.

Further Information

  • A summary of the articles that address the conversion of the 737-500 series throttle quadrant conversion, and the rebuild and update can be found in Flight Controls/Throttle Quadrant.

Acronyms and Glossary

  • AFDS - Autopilot Flight Director system

  • A/T – Autothrottle

  • CMD A/B - Autopilot on/off for system A or system B

  • Flight Avionics Software - Sim Avionics, ProSim737 or similar

  • FMC - Flight Management Computer

  • MCP - Main Control Panel

  • QAMP – Quick Access Mounting Plate

  • Throttle Arc – The arc of the thrust levers from the end of the blocks to fully forward.  The term refers to the curved piece of aluminum that the throttle levers are moved along

  • TO/GA - Takeoff Go-around switch

  • %N1 -  Very simply explained, %N1 is throttle demand and as N1 (and N2) spin at absurdly high speeds, it is easier to simply reference a percentage and display that to the crew. It's much easier for our brains to interpret a value on a scale of 0-100% rather than tens of thousands of RPM 

Searching for Definitive Answers - Flight Training

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First Officer conducts pre-flight check list & compares notes.  Whilst check lists are essential in ensuring that all crews operate similarly, there is considerable variance in how flight crews actually fly the 737

Learning to fly the 737 is not a matter of 1, 2, 3 and away you fly; there’s a lot of technical information that requires mastering for successful and correct flight technique.  Searching for a definitive answer to a flight-related question can become frustrating.  Whilst respondents are helpful and want to impart their knowledge, I’ve learnt through experience that often there isn’t a definitive answer to how or why something is done a certain way.  

Typical Pilot-type Personalities

Typical pilot personalities nearly always gravitate towards one answer and one correct method; black or white, right or wrong – virtual pilots or “simmers” behave in a similar fashion.  They want to know with certainty that what they are doing replicates the correct method used in the real-world. 

In reality, the Boeing 737 is flown by different crews in different ways all over the globe every minute of the day.   Often the methods used are not at the discretion of the crew flying, but are decided by airline company policy and procedures, although the ultimate decision rests with the Captain of the aircraft.  

For example, climb out procedures vary between different airlines and flight crews.  Some crews verify a valid roll mode at 500’ (LNAV, HDG SEL, etc) then at 1000’ AGL lower pitch attitude to begin accelerating and flap retraction followed by automation.  Others fly to 1500' or 3000’ AGL, then lower pitch and begin to "clean up" the aircraft; others fly manually to 10,000’ AGL before engaging CMD A. 

Another example is flying an approach.  Qantas request crews to disengage automation at 2500’ AGL and many Qantas crews fly the approach without automation from transition altitude (10,000’ AGL).  This is in contrast to many European and Asian carriers which request crews to use full automation whenever possible.  In contrast, American carriers appear to have more latitude in choosing whether to use automation.

Considerable Variance Allowed

The below quote is from a Qantas pilot.

  • There is considerable tolerance to how something is done, to how the aircraft is flown, and what level of automation , if any, is used. Certainly whatever method is chosen, it must be safe and fall within the regulatory framework. There are are certainly wrong ways to do things; but, there is often no single right way to do something.

Therefore; when your hunting for a definite answer to a question, remember there are often several ways to do the same thing, and often the method chosen is not at the crew’s discretion but that of the airline.

B737 Training - Videos by Angle of Attack (AoA) - Basic Review

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 “In the later part of the evening and occasionally into the wee hours of the morning, a hearty group of individuals - most of them seemingly rational, grown men and women with professional daytime jobs - sit perched in front of computer monitors with sweaty palms tightly clenching flight yokes.  Distant cries of "Honey, come to bed" have long since fallen on deaf ears as, with razor-sharp concentration, these virtual airmen skilfully guide their chosen aircraft down glide paths to airports across the world.  The late night silence is shattered by screeches of virtual rubber on the runway immediately followed by the deafening whine of reverse engine thrusters and finally a sign of relief from the flight deck - also known, in many instances as a desk! “

Why do we enjoy flight simulator?  

Is it the technical challenge learning integrated computer generated management systems, or the enjoyment of landing a virtual jetliner on a runway in limited visibility and a crosswind.  Perhaps it’s the perception of travelling to far flung locations that you probably would never visit, or maybe it’s the enjoyment received from constructing something from nothing (a flight deck).  

Which Aircraft Today - Basic Airmanship

There are many people very happy messing about with whatever they are flying.  Some will be using home computers and a joystick, others small generic style flight decks – all will have, to some degree, a level of airmanship. 

Whatever level, every individual will require at some point instruction in “how to fly” and "how to use the various avionics and instrumentation" - more so in B737 than a Cessna 172.

Flight Training –Remove Automation

A high-end simulator is a substantial investment both in time and funds.  Therefore, to obtain the best “Bang for Buck” as the Americans say, it’s more satisfying to accomplish a flight the correct way rather than the wrong way.  The B737 has numerous interfacing flight management systems and it’s important to understand what these systems do and how they interact with each other in certain phases of flight.

Flying the B737 in auto pilot mode is not difficult; the Flight Management System (FMS) does most of calculations and work for you and if you use autoland - well what else is there to do but watch.  But flying this way can be counterintuitive as you don’t really have full control of the aircraft; to fully appreciate the aircraft for what it is, you must deactivate the auto pilot and other automation and fly “hands on”.

Once the automation is deactivated, task levels multiply as several layers of information present themselves; information that must be assimilated quickly to enable correct decisions to made.  There's little room for second guessing and you must have a good working knowledge of how the various flight controls and systems interact with each other.  Add to this, inclement "virtual" weather, limited visibility, navigational challenges, landing approaches, charts, STARS, NDBS, VORS and a crosswind, and you'll find you have a lot to do in a relatively short space of time; if you want to land your virtual airliner in one piece.  And, this is not mentioning your pet dog nuzzling your leg wanting immediate attention or your girlfriend querying why the dirty dinner dishes haven't be washed!!

A page scanned from the 737-800 FCOM.  books contain a lot of information, however, they rely on the reader talready having a good understanding of the 737 systems

Technical Publications

A lot of information is readily obtainable from technical publications, on-line sources, and from the content of forums.  There are several excellent texts available that go into depth regarding the technical aspects of the B737 and cover off on a lot of the topics a real and virtual pilot may need to know (I will be looking at a few of them in future posts).  But, for the most part these texts are technical in nature and are do not include the "how to" of flight training.

One very good source of information is the B737 Flight Crew Operations Manual (FCOM).

Tutorials - PMDG

Two “how to” tutorials written by Tom Metzinger and Fred Clausen are in circulation.  These tutorials deal with the Precision Manuals Development Group (PMDG) B737 NG. These tutorials provide an excellent basis to learning how to fly the B737 and what you need to do during certain phases of flight.  Two further tutorials are available for the 737 NGX, however, they are not freely obtainable unless you have purchased the PMDG B737 NG or NGX software package.

That Nagging Feeling……Correct or incorrect ?

Despite the books, tutorials and manuals, there's always that nagging feeling that something has not been covered, is incorrect, or has been misunderstood.  We all have heard the saying “there are several ways to skin a cat”; flying is no different.  A B737 line instructor informed me that there is "a huge amount of technique allowed when flying the B737".  "There are certainly wrong ways to do things; but, there is often no single right way to do something".  Often the method selected is not at the discretion of the pilot flying, but more the decision of airline management, company policies and ATC.

Visit any FS forum and you will quickly realize that many virtual flyers do things differently.  So where does this leave the individual who wants to learn the correct way?

Short of enrolling into a real flight class, which is time consuming, very expensive and a little “over the top” for a hobby, the next option is to investigate various on-line training schools.  To my knowledge, there aren’t many formal style training classes available that provide training in the B737.  

Angle of Attack Flight Training (AoA)

Angle of Attack has developed a reasonably priced and thorough training program that incorporates ground, line and flight training for a number of differing aircraft types.   Only recently has AoA completed their B737 ground and flight training video presentations, in what amounts to many hours of valuable training.

Much of the training material is presented in video format which can either be downloaded to your computer, mobile device or viewed on-line. The content of the videos is very high resolution, well structured, professionally narrated, easy to follow, and most importantly – interesting and informative.  

HD Video, Tutorials, Flows & Checklists for all B737 Systems

AoA have followed the real-world aviation industry standard by providing a lot of system training using "flows".  A flow is a animated diagram showing step by step the correct method of doing something.  In many instances a .pdf document can be downloaded to provide a "memory jogger" for you to replicate the flow when in the simulator.

Many of the training videos build upon knowledge already gained from texts such as the Flight Crew Operations Manual (FCOM), and the use of video as opposed to only reading, provides a differing method of education which helps you to develop a greater understanding.

Video flight tutorials which take you through from pushback to shutdown and demonstrate the correct procedure for conducting a flight.

AoA only provides training for the B737 NGX, however, much of the material is backwards compatible with the B737 NG series airframes.  The video training utilises the 737 NGX model produced by Precision Manuals Development Group (PMDG) and does not use a real aircraft.

Despite these two shortcomings (NGX & not a real aircraft), the training offered is exceptional, one of a kind, and in my opinion reasonably priced.  

Digital Chronograph Running ProSim737 Software

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The Main Instrument Panel (MIP), unless a special order is made, usually will not include a chronograph.  Depending upon the MIP manufacturer, the MIP may have a cut out for the chronograph, a facsimile of a chronograph or just a bezel. 

LEFT:   OEM chronograph used by America Airlines.  Nothing beats an OEM item, however, in this case conversion is difficult and a reproduction more cost effective.  Image courtesy of Micks737.

The Next Generation aircraft mostly use digital chronographs. The classic series airframes usually use (unless retrofitted) mechanical chronographs.

After Market Chronograph

There are several after-market chronographs that can be purchased.  SISMO Solicones produce a mechanical type that replicates the real world counterpart quite well, despite the awful orange-coloured backlighting.  Flight Illusion produces a quality instrument as does Flight Deck Solutions (FDS).  FDS replicate the digital chronograph. 

Chronographs are manufactured by several companies and not every chronograph looks identical, although their functionality is.  There are a few different styles available to an airline.  The main difference is in the number and shape of the buttons; round or rectangular.

No matter which type you decide, be prepared to shell out 250 plus Euro per chronograph; for an item rarely used it's quite a financial outlay.

Converting OEM Chronograph

Converting an OEM B737 mechanical chronometer is a valid option and the process of conversion is relatively straightforward.   However, finding a mechanical chronograph in operational order is difficult, as airlines frequently keep chronographs in service for as long as possible.  Converting a digital chronograph is also an option, however, the initial price of the item and then conversion make this an expensive exercise.  Add to this the fact that converting the chronograph, due to its internal digital electronics is very difficult (even if you use ARINC 429 protocol).

Another option is to use the virtual chronometer (Sim Avionics and ProSim737) and fabricate a reproduction bezel that overlays a small LCD screen.

ProSim737 Virtual Chronograph

Screen capture of ProSim737 chronograph.  ProSim737 have a Chronograph that can be used for the Captain and First Officer side of the MIP.  There are seevral version of the display that can be used

ProSim737 as part of their avionics suite have available a virtual chronometer.

The display used by ProSim737 is very crisp, the size is accurate (1:1 ratio), and the software allows complete functionality of the chronograph. 

To use the virtual version a small computer screen is needed on which is displayed the virtual chronograph.

Chronograph

A friend of mine indicated that he wanted to make a chronograph for the simulator and use the virtual ProSim737 display.  He also wanted to incorporate the four setting buttons and have them fully functional. 

The components needed to complete the project are:

  • A small TFT LCD screen (purchased from e-bay);

  • A standard Pokey interface card;

  • Several LEDS; and,

  • Four small tactile switches and electrical wire. 

I currently use an Main Instrument Panel (MIP) fabricated by Flight deck Solutions (FDS).  Therefore, the chronograph bezel used in this project was that supplied by FDS.

The screen used was 5.0" TFT LCD Module with a Dual AV / VGA Board 800x480 with a 40 Pin LED Backlight. 

The screen was small enough that it just covered the circular hole of the cut out in the FDS MIP.  The TFT LCD screen uses a standard VGA connector cable, 12 Volt power supply and a USB cable to connect the POKEY card to the computer.  

The holes in the box provide ventilation for the Pokeys card.  The only portion of the box that is visible from the front of the MIP is the bezel and four buttons

Two-part Fabrication

FDS supply with their MIP a bezel with four solid plastic but non-functional buttons.  The bezel does not support direct backlighting, nor does it have enough space for tactile switches or wiring. 

Therefore, the FDS bezel must be modified to accommodate the wiring for the switches and LED illuminated backlighting. The easiest way to approach this modification is to use a Dremel rotary tool with a 9902 Tungsten Carbide Cutter.

Place the bezel on a hard surface using a towel to avoid scratching and damaging the bezel.  Then, with 'surgical' accuracy and steady hands carve out several channels (groves) at the rear of the bezel.  The channels enable placement of the miniature tactile switches, small LEDS and wiring. 

Space is at a premium, and to gain addition real estate, the LEDS were shaved to remove excess material.  This enabled the LEDS to fit into the excavated groove on the bezel.  Be very careful when using the carbide cutter to not punch out onto the other side of the bezel. 

The four solid plastic front buttons on the bezel are carefully removed and small tactile switches attached (glued) to the rear of each of the buttons.   26/28 AWG wire is used to connect the tactile switches (using common ground leads) to a PoKeys interface card. 

The box is not seen as it's attached to the rear of the MIP.  My friend's humour - several warning signs suggesting that I not tamper with his creation :)

Box Fabrication

A small box needs to be fabricated to house the Pokey card.  The size of the box is controlled by the size of interface card used and the length and width of the LCD screen. 

A box is not required, however, it's a good idea as it illuminates the need to seal the LCD screen to illuminate dust ingress between the screen and overlying glass in the bezel. 

The material used to fabricate the box is plastic signage card (corflute); real estate agencies often use this type of sign.  The main advantage of this material is that it’s not difficult to find, is light in weight, and it's easy to cut, bend, and glue together with a glue gun.    

After the Pokey card is installed to the inside of the box, and the LCD screen attached to the front edge, the bezel needs to be secured to the front of the LCD screen.  The best method to attach the screen and bezel is to use either glue or tape. 

A hole will need to be made in the rear of the box to enable the fitment of the USB and VGA connectors.    Small holes punched into the side of the container ensure the LCD screen and PoKeys card do not overheat.  If you're concerned about heat buildup, a small computer style fan can easily be added to the box, but this does add complexity and is not necessary.  To conform to standard colours, the box is painted in Boeing grey.

LED Backlighting

Careful examination of the backlighting will show that the light coverage is not quite 100%.  There are two reasons as for this.

(i)    There is limited space behind the bezel to accommodate the wiring and the LEDS; and,

(ii)   The material that FDS has used to construct the bezel is opaque.  The only way to alleviate this is to replace the stock bezel with another made from a transparent material.

Important Point:

  • If you want to try and replicate the digital OEM chronograph as closely as possible, that the OEM version does not use backlighting.  Illumination of the front of the chronograph is by the MIP lighting.

Potential Problem

Depending on the MIP being used, there maybe space constraints that do not allow a 5 inch screen to be easily positioned.   If you're forced to use a smaller screen, the outcome will be that you may see the screen edges within the bezel.  For the most part this is not an issue, if you ensure the desktop display is set to black.  Remember, you are looking at the chronograph from a set distance (from the pilot seat) and not close up.

ProSim737 Virtual Chronograph (position and set-up)

This task is straightforward and follows the same method used to install and position the PFD, ND and EICAS displays.  

Open ProSim737’s avionics suite and select the virtual chronograph from the static gauges:  resize and position the display to ensure the chronograph conforms to the size of the bezel.  To configure the buttons on the bezel, so that ProSim737 recognizes them with the correct function, open the ProSim737 configuration screen and configure the appropriate buttons from the switches menu (config/switches).

The four functions the buttons are responsible for are:

(i)    Chronograph start;

(ii)    Set time and date;

(iii)   Expired Time (ET) and Reset; and,

(iv)   +- selection

NOTE:  The above functions differ slightly between the panel and the virtual chronograph in use.

Chronograph Operation and Additional Configuration

Captain-side CLOCK start button.  Connection between the clock button and the CHR button is made in the assignments page in ProSim737 (FDS MIP)

The chronograph can be initiated (started) by either depressing the CHR button on the top left of the clock, or by depressing the CLOCK button located on the glarewing of the MIP. 

Configuration

Connecting the CLOCK button to the chronograph start (CHR) function is straightforward.

Connect the two wires from the Captain-side clock button to the appropriate interface card and configure in the switches tab of ProSim737 (config/switches/CAPT CHR).

The same should be done with the First Officer side CLOCK button and chronograph, however, ensure you select the FO CHR function in switches to be done for the First Officer side chronometer if fitted.

If configured correctly, one press of the CLOCK button will start the chronograph, a second press will stop the chronograph, and a third press will reset the chronometer to zero.

After Market Chronograph

For those wanting to use an after market chronograph, SimWorld in Poland and Flight deck Solutions (FDS) in Canada produce high quality chronographs that can be dropped into the MIP with minimal required fabrication.

Video

A short video (filmed at night) showing the new chronograph running the virtual ProSim737 software.  Note that the chronograph displas is slightly smaller in the video to what it should be.  Adjusting the size of the display is done within the ProSim737 software.

 
 

Update

on 2020-06-18 03:27 by FLAPS 2 APPROACH

Another flight deck builder has also constructed a chronograph using similar methods.  His chronograph uses a different design that does not use a box. 

Update

on 2020-05-23 01:00 by FLAPS 2 APPROACH

In August 2019 this chronometer will be replaced.  The replacement will use a similar design, however, will not be encapsulated in a box that fits behind the MIP.  The new design will incorporate a å larger 5" TFT LCD screen that will enable more screen real estate for the chronograph.  The screen will be mounted directly to the rear of the MIP and the interface card will be adhered to the rear of the screen. 

The reason for changing the design is two-fold:

  1. The box is quite large, and the weight (although light weight) is heavy enough to cause the bezel to pull away from the MIP; and,

  2. Accessing the interface card is difficult (as it's inside the box).

An article explaining the process will form a new article.  The new chronograph very closely follows the design used by FlightDeck737.BE

Converting Genuine B737 Audio Control Panels (ACPs)

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oem 737-400 ACP. this will be a filler until two next generation ACPs are found

I have looked at several commercially made Audio Control Panels that are available for connection to flight simulator – I did not like any of them.  They all seemed to lack a certain degree of authenticity, whether it was the LED backlighting rather than bulbs, poorly designed and moulded switches, or out of alignment cheap-looking plastic buttons.  The only ACP units that interested me where those produced by Flight Deck Solutions, however, the price for two units was greater than purchasing two genuine second-hand ACP units. 

What is an ACP

ACP stands for Audio Control Panel and the B737 has three units; one in the aft overhead and two (captain & first officer) in the center pedestal.   Each panel controls an independent crew station audio system and allows the crew member to select the desired radios, navigation aids, interphones, and PA systems for monitoring and transmission. Receiver switches select the systems to be monitored.  Any combination of systems may be selected. Receiver switches also control the volume for the headset and speaker at the related crew stations. Audio from each ACP is monitored using a headset/headphones or the related pilot’s speaker.

Simply, the ACP is a glorified sound mixer.

Finding second-hand ACP units from a B737-800NG is next to impossible, so the next best thing are units removed classic series 737s.  The units I am using were manufactured by Gables Engineering in 2004 and have been removed from a B737-500.  It is unlikely that ACP units from an earlier series aircraft would be used in the NG, as the NG ACP unit design is different.  But, for a home-made simulator the use of older ACP units fulfils the same roll and is a very good stop-gap until a OEM NG panel can be procured.

When you begin to search for ACP units, you will discover there are a large number of different designs available.  The design can be correlated to the era of the unit.  Earlier units used sliders and turn dials while later models utilised push buttons.   Many of the slider-style units were used in 727s. 

Conversion of ACP Unit to Flight Simulator - Several Methods

It is difficult to document exactly how a conversion is done.  There are many variables to consider and genuine parts and flight simulator set-ups can be different.  By far the most challenging task is determining which wire from the 55 pin plug controls which ACP function.

oem 737-400 ACP unit with outer shell removed.  Most of this will be removed with the exception of the switches.  The wiring can be removed and replaced or unraveled and used directly

Removing Unwanted Wiring

You can either start afresh and after removing the outer aluminium casing, strip most of the wiring from the unit, along with discarding unwanted solenoids, relays and the large circular 55 pin plug at the rear of the unit; or keep the wiring and 55 pin plug and attempt to determine which wire goes where and and connects with what function. 

When finished removing much of the unwanted interior you will be left an almost empty container and some hardware and electrical circuits (buttons and switches).  Most of the switches are triple push switches and you must be careful to not damage the internal mechanism of these switches.

Which Wire Goes Where and Connections

There are two ways to convert the unit:  The first is to use existing wiring and determine which wire goes to what button/switch to reflect whatever functionality; this can be a time-consuming, challenging and frustrating task.  Once the wire to a function has been found, you must identify the wire with a flat tab or other physical marking device.  Each wire is then directed to an interface card.

The second method is a little easier.  Remove all the wires are rewire the unit.  This way there is no double-guessing that you have the correct wire.

If you have opted for the slightly easier second method of removing all the wiring from the unit and starting afresh, you can now recycle the same wire and solder the wires to the appropriate switches.  Recycling in motion :)

Determining Functionality

One method to determine functionality is to use a digital multi meter.  Set the meter to either continuity or resistance, select a wire connected to a switch and place the probe at the open end of the wire.  Identifying the correct wire/switch will cause the meter to either emit an audible beep or display a resistance on the display.  This is the wire that connects this function.

Once the wires have been identified and connected to the correct hardware switches within the ACP unit, they are then connected to an interface card.  I have used a Leo Bodnar BU0836X card which has available a large number of inputs and outputs. 

The Leo Bodnar card provides the interface between the ACP units and flight simulator.

To keep the wiring tidy, bundle the wires into a wiring lumen terminating in a solid plug / connector.  In my case I've used a standard style 18 pin computer connector. 

It is important to use a plug, rather direct the wires directly to the interface card, as you may wish to remove the ACP units at some stage.  A plug allows easy removal and connection.

Leo Bodnar card and two wire rails connected to acyclic board.  The vertically mounted wire rail provides a strong support from which to solder the wires.  The two computer plugs connect to the rear of each ACP unit.  The other small blue coloured card is an FDS power connection card used to daisy chain 5 Volt  power to the FDS modules I am using

Wiring Harness, Rail and Backlighting

A wiring harness was constructed to facilitate easier connection of the wires from the ACP units to the interface card. The harness and Leo Bodnar card is attached to a thick piece of acrylic plastic which in turn was mounted to a piece of wood that fits snugly within the center pedestal.

Wire Rail

Each ACP unit has a dedicated 'wire rail' attached to an acrylic plastic base.  The purpose of this rail is to provide an interface between the ACP units and the Leo Bodnar card.  Whilst this interface is not absolutely necessary, it does allow for identification of the wires (numbering system seen in photograph above).  Furthermore, it also provides a stable and solid base to secure wires between the interface card and each of the ACP units.

It should be noted that the rail also acts as a Y-junction to filter the outputs from two ACP units into one, which connects to the interface card and flight simulator.

The wires from the rail are then soldered to a standard style computer plug which connects to its male  equivalent mounted to the rear of each ACP unit. In essence we have three parts to the system:

  1. A re-wired ACP unit with wires terminating in a plug on the rear of the unit. 

  2. A wire rail which sits between the two ACP units and the interface card (Y-junction).

  3. An interface card that  connect with the wire rail and then to flight simulator via a USB cable.

Soft amber glow of ACP unit back lighting at night.  The light plates of genuine units always use globes rather than LED lights.  Power is 5 Volts DC and the amperage draw is around 1 AMP

Backlighting

The wires which carry power to illuminate the back lighting are wired directly from the light plates located in each ACP unit to a small electrical terminal block mounted to the rear of the unit.  The power wire is then directed to the panel light switch, located on the center pedestal. 

The panel light switch, located on the center pedestal,  controls back-lighting to the throttle quadrant, center pedestal and to the trip indicators on the yokes.  The reason for breaking this power wire with a two-wire terminal block is to allow removal of the ACP unit if necessary.  If you wanted to, you could use a pencil style audio push-in style plug.

A single USB cable from the Leo Bodnar card connects the ACP units to the main FS computer.

Synchronised Units - Limiting FSX Factor

In a real aircraft each ACP unit is separate to each other and can be configured independently, however, flight simulator (FSX) falls short in this area and uses only one ACP unit to mimic button presses across all units. As such, it was pointless to wire each unit separately and independent of each other.  Therefore, both ACP units mimic each other in functionality and output. 

For example, the ADF1 button can be pressed on the captain-side ACP unit to turn ADF1 on.  If you then press the same button on the flight officer side unit, ADF1 will be turned off.  This is another reason why a wire rail, mentioned above, was used; to act as a Y-junction.

NOTE (January 2015): ProSim737 now allows configuration of all buttons on the Captain and First Officer ACP units.  ProSim737 now allows independent selection of an ACP unit (up to three) removing the earlier FSX-imposed limiting factor.  Both units have been re-wired to take this into account.

Converted ACP unit showing replacement wiring and 18 pin computer style plug.  The circular hole in the rear below the plug is where the 55 pin plug was removed

Control - Captain or First Officer

Some enthusiasts wire units so that the Captain side is always the main controlling unit.  In my set-up, the wires from each ACP unit are fixed to the 'wire rail' and then to the Leo Bodnar card.  This allows you to be able to choice either side as the controlling unit.  The downfall being that whatever side is not in control must have the correct buttons pre-selected for correct operation.

Ingenious Design

One very interesting aspect of the ACP units is how Gables Manufacturing has designed the buttons to illuminate light when activated.  I initially thought that each button would have a separate bulb; however, this is incorrect.  The light which illuminates a button when engaged, comes directly from a number of strategically positioned bulbs.  An ingenious design incorporates a small reflector dish similar to an old style camera flash unit, to stop light reaching the button when it is in the unengaged position.  Engaging the button moves the dish into alignment which reflects back light into the button’s clear acrylic interior.  

Although an ingenious design, you must be very careful if handling a button to ensure that the reflector, which is positioned between the base of the button and light plate, does not 'bounce' away to be lost.

Configuring Functionality

Configuring ACP functionality, once the wiring is correctly connected, is straightforward and can either be done directly through the control panel in FSX, through FSUIPC or directly from within ProSim737.

The pencil-style and square-type buttons of each ACP unit allow quite a bit of functionality to be programmed when using FSUIPC.  Not every ACP feature, used in a real aircraft is replicated in flight simulator; therefore, those buttons not used for essential audio functions can be used for other customised functions.  

The most important functions (in my opinion) to have working are the indents for: VHF, NAV 1/2, ADF 1/2, MRKS (markers) and DME.  COM 1/2 transmit buttons can also be configured easily in FSUPIC to use  when flying on VATSIM or IVAO.

I have not configured the audio (volume) on the pencil-style buttons; however, it may be possible to configure these at some later stage using a separate sound card.  I believe the potentiometers  range from 11.90 - 12.00 K Ohms.

Aesthetics

I think you will agree that the OEM ACP units, even if not NG style, look much better than replicated modules – even if they are not the latest NG style:  the genuine buttons and switches, the soft amber glow of real Boeing back-lighting, and the substantial build of the units generate a high level of immersion.

NG Style ACP Units

The units are not NG style, however, as New Generation parts come on-line, I will replace these units with the more modern style.  it iss just a matter of waiting for 600 and 700 series units to become available.

I've compiled a short video using Ken Burns effect.

 

737-500 ACP conversion (Ken Burns effect)

 

POST SCRIPT - An Easier Method: Schematics to ACP Units and 55 Pin Outs

At the time of my conversion, I did not have available a schematic showing the pin outs for the ACP unit.  This meant any conversion had to be done from scratch (as documented above). 

I now am in  possession of the ACP schematic diagram, which includes a pin out diagram indicating what function each pin of the available 55 pins on the rear plug connects to. 

diagram !: standard 55 pin plug found on Gables ACP units

If another conversion is required, the wiring will be a lot simpler as the wires will not need to be striped from the unit and re-done.  All that will be needed is to attach wires from the Leo Bodnar card directly to the 55 pin electrical plug already mounted on the rear of each ACP unit (I have been reliably informed, that thin 1mm copper pipes obtainable from modelling supplies fit perfectly), and connect the light plates to a 5 Volt DC power source. 

Minor Complications

At first, using the 55 pin plug appears to be an easy method of conversion, however, there is a minor set-back.  The COM radio cannot be connected; it is probable that on the real aircraft the MIC selectors are routed via onboard amplifiers rather than via the plug.  Therefore, if these functions are required, they will need to be converted by rewiring and connecting to a accessory plug of some type (as has been done documented in the first section of this post).

Do Not Reinvent The Wheel - Canon Plugs

It is important to always try and convert any OEM part using the Canon plugs and pin outs before rewiring any part.  Gables have already done an excellent job  wiring the panel internally, so why not utilise this wiring by using the existing Canon plug system.

This ACP panel is the only panel that has been converted this way in the simulator.  It was the first panel that was converted and at the time I did not understand the Canon plug concept in its entirety.  All other panels have been converted using the existing plug system avoiding rewiring the unit.

Update

on 2020-07-05 01:50 by FLAPS 2 APPROACH

One minor problem observed using the standard Leo Bodnar interface card, is that the connection of the wires into the card kept working their way loose, resulting in a break in the connection.  This problem identified itself by giving incorrect button designations on the ACP units.  No matter how hard I pushed the wires into the holders on the card, the wires eventually worked their way out a tad.

To solve this issue, I replaced the BUO836X card with the Leo Bodnar BBI-32 Button Box card.  The BB1-32 card allows the wires to be soldered in place.

Update

on 2015-07-30 06:20 by FLAPS 2 APPROACH

Following on with converting as many units to be 'plug and play', the ACP units were once again revamped to allow the Leo Bodnar card to be installed inside the Captain-side unit. 

Captain-side master ACP showing reworked connectors.  One straight-through cable connects between the master and the F/O ACP (slave) while the other cable connects with its mate inside the pedestal bay.  The USB cable connects with a USB hub located in the pedestal.  If I was converting the ACP units again, I would definitely use Canon plugs

The Captain-side ACP is the 'command' unit and the F/O ACP units acts as a 'slave'.  A straight-through cable connects both units via D-sub plugs (the computer-style terminal plugs were removed).   A single USB cable connects the Captain-side ACP to the computer. 

Further, the limiting aspect of having to have the F/O side activated to allow functionality to occur on the Captain side has been removed.  Historically, FSX has only allowed the ACP units to operate from the Captain side.  ProSim737 enables operation of three ACP units, so this limiting factor is now removed. Each button on both ACP units has been wired to allow separate control.

The benefit of installing the joystick card inside the unit is it removes the large amount of wiring that  previously used valuable real estate space within the center pedestal.  

Update

on 2022-05-09 12:26 by FLAPS 2 APPROACH

This conversion was completed sometime ago (2014-15).  Today (2020) there are more efficient and easier ways to convert the ACP units that do not require the unit to be completed gutted.  Certainly, the outcome is identical, but the method different.

If converting another ACP unit, I would not use the method documented above.

Using Genuine B737 Aviation Parts

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A colleague grinding the tails from genuine DZUS fasteners. These will then be attached to reproduction modules to enhance their appearance

There is something fundamentally different when using a genuine piece of aircraft equipment instead of a replicated item – It’s difficult to define, but the idea of using a piece of hardware that flew thousands of flight hours, in good and bad weather, has a certain appeal.

You will notice when you peruse the below list that many parts are not Next Generation, but are from classic 737 airframes, Finding Next Generation components is time consuming and can have long lead times. In the interim, I am using classic parts as fillers. Fortunately, some components used in the classics, especially the 737-500 are also used in the Next Generation.

The following OEM parts are currently used and converted:

  • 737-500 yokes and columns (2)

  • 737 Captain-side stick shaker

  • 737-300 throttle quadrant

  • 737-300 telephone and microphone

  • Jetliner style aviation headset (was formally used in an United B737)

  • 737-300 three-bay center pedestal

  • 737-400 fire suppression panel

  • 737 yoke trip indicators (2)

  • 737 rudder pedals (2)

  • 737-500 audio control panels (2)

  • 737 Weber captain and first officer seats

  • MD-80 clock (flight officer side of MIP)

  • 737 overhead map light

  • 737 korry switches

  • 737-500 tiller handle

  • 737-300 Forward & Aft Overhead Panel w/ Coles engine switches & genuine light switches

  • DZUS fasteners

  • 737-800 flap guage

  • 737-800 Yaw Dampener gauge

  • 737-800 brake pressure gauge

I would like very much like to replace the ADF and NAV modules with OEM panels; however, need to research the feasibility in doing this.  In the meantime, I’m using reproduction navigation radios manufactured by Flight Deck Solutions.

Historical Significance

The historical significance of using genuine parts cannot be ignored.    It’s relatively easy to research an aircraft frame number or registration number and in the process learn where the aircraft was used and in what conditions.  

For example, the throttle unit I am using was removed from a South West B737-300 that plied the continental USA for many years, whilst the yokes and columns were previously used in a B737-500 operated by Croatian Airlines.  The clock I have for the flight officer side of the MIP came from a FedEx MD80 and one of the ACP units was used by Aloha Airlines in Hawaii.

Recycling

Using OEM used parts helps the environment!  

For a start, you are not purchasing new reproduction parts made from virgin resources.  Secondly, the used parts you bought probably would have been destined for expensive recycling, or alternatively disposed of to landfill.  

Recycling can be fun!!  

It’s a good feeling to convert something destined for disposal and bring it back to life.

Toughness

One of the major benefits of using OEM aircraft parts is their longevity and ruggedness.  Whilst none of us want to damage our simulators through over zealous use; it can and does occur from time to time.  Replica parts are – well a little delicate.  To ensure long life you must treat them with care.  

It’s the opposite with genuine aircraft parts; damaging a genuine part with normal use is almost impossible.  

For example, a speed brake lever is relatively easy to bend or break on any number of replica throttle quadrants on the market; damaging a genuine speed brake handle is very difficult as they are constructed from high grade materials to withstand genuine stresses (pilot-driven or otherwise).

Simulation pilots are often as rough on their gear as genuine pilots are; I’ve seen simmers jab ACP buttons with enough force to break a piece of plastic.  Genuine buttons are made to withstand this heavy-handed treatment, replica parts – break!

Aesthetics – Look Your Best

It’s a fact; aN oem aircraft part looks 100% more realistic than a simulated part – that’s obvious.  If your center pedestal has an assortment of genuine modules mixed in with replica modules, the pedestal will appear much more authentic than one comprised solely of simulated units.

You will be surprised that small things can make a huge aesthetic difference.  Take for example, DZUS fasteners.  I bought a box of fasteners sometime back and use them wherever I can to replace the reproduction fasteners or screws that many manufacturer’s use.  If the fastener does not fit the appropriate hole in the reproduction module, I either enlarge the hole with a drill bit, or if this isn’t feasible, I cut the tail from the fastener leaving only the DZUS head.  I then use a piece of sticky blue tack or crazy glue to secure the DZUS head to the appropriate part.  

OEM B737-300 two-bay center pedestal showing mix of reproduction and oem components

The fasteners I've used were purchased second-hand; therefore, they show wear and tear.  I don’t mind this used and abused look.  Yes it sounds rough and ready, but the end result looks very pleasing to the eye and more faithful to what you would see in an operational flight deck.

The confines of the flight deck are not as clean as one might expect, and instruments are scratched and dented; pilots rarely concern themselves with aesthetics and technicians complete their maintenance quickly, as an aircraft not flying equates to lost revenue for the airline.

The use of genuine parts adds to the immersion factor, and as a Dutch simmer recently commented: “It makes the simulator more alive”

Availability of Parts

oem aircraft parts can be difficult to find and it’s a hit and miss affair.  As newer aircraft are brought online, airlines scrap their older fleet and parts become readily available.   

Finding late model Next Generation parts, at a reasonable price is almost impossible; these parts are still serviceable.  Parts in older aircraft may also be serviceable; however, they must meet safety regulations and be inspected and approved by a certified agency.  This process is expensive and many airlines find it cost prohibitive; therefore, parts are sold as scrap.

E-Bay can be a good place to find parts.  Search for aviation parts - Boeing, 737 or Gables.  Aviation scrap yards are also invaluable, as are the classified sections in various flight simulation forums on the Internet such as My Cockpit and Cockpit Builders.

Conversion - Use in Flight Simulator

This can be minefield to the uninitiated.

OEM parts often operate on a variety of voltages, and it’s not uncommon to need 5, 12, 18 and 24 Volt power supplies to enable an OEM part to work correctly.  Further, the wiring inside the neat-looking box can be a rat’s nest of thin wires weaving their way to and from a variety of unidentified pieces, before terminating in an electrical connection rarely found outside the aviation industry (Canon plug).

I am not an expert in conversions (although I am learning quickly.....).  I’m lucky in that I have access to a few people who are very knowledgeable in this area and are happy to share their knowledge with me.  

Interfacing

There are a number of ways to interface an OEM part with flight simulator.  The easiest is to use is a Leo Bodnar BU0836 joystick card, or similar, using standard flight simulator commands and/or FSUIPC.  The use of these cards makes assigning functionality in flight simulator very easy and straightforward.

One BU0836 card provides 12 inputs which correlates to 12 individual switches or buttons.  The 0836 card also has the capability to have a matrix constructed which increases the number of available outputs.  Another joystick card that is very good and easy to configure is the PoKeys card.

The inside of a 737-500 ACP module showing the rat’s nest of wiring that can be found within an OEM module

For functionality that requires movement, a servo motor will need to be used and configured in FS2Phidgets.  Phidgets allow you to program almost any moving part, such as the needle of the rudder trim module or the trim wheels of a throttle unit.    Digital servos are better than analogue servos as the former do not make an audible squeaking noise when connected to power.

By far, the most difficult part of any conversion is discovering what wire connects to what functionality.  Finding the wire can be challenging in itself as most avionics modules are a nest of wires, diodes and electronic circuitry.

You Have A Choice

You don’t have to use reproduction simulator parts throughout your flight deck – there is a wide selection of used aviation parts available, and with a little searching, you probably can find what you want.  

OEM parts frequently can be found at far less cost than their reproduction counterparts, and in every case will always look more visually appealing.  If you’re not up to the task of conversion, there are individuals that can convert modules for you.  You will then need to configure the functionality in FSUIPC or directly in the avionics suite used.  At the very minimum, using DZUS fasteners will bring your simulator to the next level of realism.  But be warned, using OEM parts evokes a desire to replace anything replica with something real.

In my next post we will look at converting two genuine B737 Audio Control Panels (ACPs) to flight simulator use.