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Mission Statement 

The purpose of FLAPS-2-APPROACH is two-fold:  To document the construction of a Boeing 737 flight simulator, and to act as a platform to share aviation-related articles pertaining to the Boeing 737; thereby, providing a source of inspiration and reference to like-minded individuals.

I am not a professional journalist.  Writing for a cross section of readers from differing cultures and languages with varying degrees of technical ability, can at times be challenging. I hope there are not too many spelling and grammatical mistakes.

 

Note:   I have NO affiliation with ANY manufacturer or reseller.  All reviews and content are 'frank and fearless' - I tell it as I see it.  Do not complain if you do not like what you read.

I use the words 'modules & panels' and 'CDU & FMC' interchangeably.  The definition of the acronym 'OEM' is Original Equipment Manufacturer (aka real aicraft part).

 

All funds are used to offset the cost of server and website hosting (Thank You...)

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If you see any errors or omissions, please contact me to correct the information. 

Journal Archive (Newest First)
Saturday
Dec262015

Are You Protected - Power Surges 

The power requirement, or more to the point the regulation of the power is often overlooked when building a functional flight deck. 

A basic desktop-style simulator controlled by a single computer and displayed on two computer monitors will draw very little power and can easily be connected to a single household wall socket.  However, as a simulator build becomes more complex and incorporates multi-displays and various other pieces of equipment the power requirements become more complex.  

In this post, I will discuss the basics surrounding the distribution of power, in particular amperage draw.  I will also address the need for surge protection. 

This post is an introduction into the somewhat confusing and complicating world of electricity and power quality; it is not intended to be a definitive work.

Amperage Draw

The biggest issue with many simulators is amperage draw, with many builds drawing close to, if not over 10 amps.  Drawing in excess of 10 amps can cause a standard household circuit breaker (or fuse) to be triggered cutting off the electricity supply to the simulator.

Although a power shut down from the triggering of a circuit breaker can be annoying, especially if part way through a simulator flight, a bigger problem is that many interface cards including Phidget cards may lose important configuration and calibration parameters if they are ‘murdered1by a power shutdown.

Amperage Draw, Circuit Breakers and Zones

The power distribution in a modern house is distributed into zones (circuits).  

A zone will have any number of power points attached to it, and will be protected by a dedicated circuit breaker of specific amperage.  For example, water and heat is one zone, while lighting and power points can be spread across one, two or more zones (depending on the number of lights and their respective amperage draw). 

In Australia, all standard household power points (except heat and water) are rated at 10 amps while the wire that runs from the power point to the circuit board is rated at a higher capacity; usually 15 amps.  

If the power requirements exceed 10 amps within a zone, then the circuit breaker on the circuit board will be triggered and the electricity will cease to flow into that zone.

Many will be accustomed to this inconvenience, when they have a number of heaters plugged into various power points within one zone.  Turning on the kettle to boil water, will then be enough to exceed the power amperage for that zone and the circuit breaker will be triggered.

  • My next post will take a more detailed look at circuit breakers and the types that can be used in various situations, so more more on this later.

Amperage Draw and Heat

An easy method to enable a greater amperage draw is to replace the 10 amp circuit breaker with one rated at a higher capacity.  This will alleviate the situation of the circuit being tripped every time you exceed 10 amps.  Whilst this is feasible, after all the wire running between the board and the power point is 15 amps, it is not recommended.  

A by-product of drawing too many amps along one wire is heat, and although the wire may be rated at 15 amps, the heat may cause electrical wrapping to begin to melt.  Furthermore, if the amperage draw is maintained the power point may begin to melt and burn due to the exceeded amperage draw.

Calculating Amperage Draw

Calculating the amperage draw can be complicated as equipment can draw different amperages at different times.  For example, a computer when turned on will initially draw more amperage; however, this draw will lower after the initial start cycle has been completed.  

LEFT:  Amperage draw and status can be measured if an appropriate gauge is installed and the wiring connected correctly.  The gauges in the picture are measuring amperage status of different sectors (5  & 12 volt sectors) in the Throttle Interface Module.

Often, you can cause an over-amperage draw and trigger a circuit breaker by starting everything simultaneously.  However, by starting different systems sequentially you can keep the amperage draw to a minimum and below the 10 amp rating of the circuit breaker.

Upgrading the Amperage

If the simulator (or any number of electrical appliances) draws more than 10 amps, and the circuit breaker continuously is triggered, there are two methods in which to solve the problem.  

First, is to have an electrician replace the wire for the zone that the simulator is connected to.  This involves replacing the 10 amp power point with a power point rated at 15 amps, running higher capacity wire between the power point and circuit breaker, and using a higher amperage circuit breaker in the circuit board.  A 15 amp power point also incorporates a larger blade assembly (earth) on the plug..

The second method is to spread the power requirements over two or more zones.  This way, if the simulator operates across two 10 amp zones you will have 20 amps of power available.

The downside of the second method is that you will need to have power points in close proximity to each other that connect to two zones; otherwise, an extension cable may need to be run between the simulator and the designated power point.

Power Surges, Noise and Clean Power

Unfortunately, power is not clean and everyone will experience at sometime or another voltage fluctuations (power surges).  The severity and frequency of the fluctuations will depend  upon the ability of the power grid to obtain, store and distribute power.  

LEFT: Sine wave data read-out showing the tell-tail spike  of a power surge.

The power requirements of a large industrial complex powering on in the morning maybe enough to cause a fluctuation (surge) as it draws initial power from the grid.  Furthermore, surges in power can often occur when the electrical company adjusts the grid to take into account the day and night-time power requirements of the surrounding region.  

Whilst these are standard day to day activities, a major disruption in power, with resultant surges and spikes, can occur during severe storm events.  During such events, power disruptions can be common as poles and wires are damaged due to high wind and torrential rain.  In the most extreme case, an electrical discharge from lightening can occur directly on your home or in an area nearby.  If your house is struck by lightning, then there is very high chance that permanent damage will result to any plugged in equipment.

Is this problematic – yes and no.  An odd low level minor surge will probably not cause too much grief; however, a high volume power surge or a constant surge can damage equipment.  

A high-end simulator usually incorporates numerous interface cards, system boards and other delicate components which, more often than not, are not amiable to power surges.  

A high volume or constant power surge may destroy the motherboard, power supply and USB PCI cards in the computer, in addition to destroying interface cards attached to the computer.  However, minor power surges may not enlist any observable damage (other than the lights flickering or dimming briefly), but they may shorten the effective life of attached components leading to premature burnout.

Surge Protection and How It Works

There are several pieces of equipment that can be used to protect electronic equipment; the most common being a surge protector board.  

LEFT:  Six plug power surge protection board with internal circuit breaker manufactured by Belkin.  Two LED lights indicate on/off and earth leakage while the circular black pop out switch is a standard-type circuit breaker.  The Belkin is probably one of the more popular boards and provides average protection with a rating of around 600 Joules (depends on model) (click to enlarge).

In essence, a surge protector board is a glorified power board with some type of mechanical mechanism that is either destroyed or partly destroyed when a power surge occurs.  Higher end protectors may also provide noise filtering and a internal circuit breaker.

The level of protection provided by a surge protector is, at its bare minimum, determined by the level of Joules the board is rated at.    Joules (J) is a derived unit of energy as defined by the International System of Units and should be thought of as a reservoir of protection.  

Simply put, a board rated with a high number of Joules has a larger reservoir and therefore provides greater protection for a longer period of time.   For example, if a board is rated at 525 Joules, the board will provide protection for either one power surge rated at 525 Joules or any number of smaller power surges below 525 Joules until the rating is exceeded.  

The design of the board is such that once the level of protection (Joules) has been exceeded, the board will need to be replaced.  

Many minor power surges go completely unnoticed, and although you did not notice the surge, the surge protector will have filtered the power imbalance and lost a portion of its own protection (Joule reservoir).  This can lead to a false sense of security as many protector boards will still function, albeit without any form of available protection.  Inexpensive surge protectors often do not have any type of indicator to warn when their Joule reservoir is about to, or has been exceeded.

Re-set Buttons

Many surge protector and extension boards have a reset button.  The reset button has nothing to do with surge protection or resetting the board after a power surge has occurred.  Rather, the button is the reset for the circuit breaker which is for protection against a short circuit or over-load condition that could otherwise cause the wiring to melt with the board.

Main Types Of Power Surge

The following is an excerpt from Electrosafe, a company based in New Zealand.

Dropout

This is where a portion of the sine wave has a lower than expected value or is missing entirely, usually for a portion of a cycle. These types of problems can be caused when large motors are started, spot welders are operated, lightning arresters conduct (during a lightning hit), or when electrical equipment fails. Dropouts can lead to failures in computers and electronic equipment, reduced life of motors and flickering lights.

Power Failure

When the duration of a dropout exceeds 1 cycle it is usually referred to as a power failure, or blackout. This problem is usually the easiest to recognise.

Sag or Brownout

A power sag (or low line voltage) is a decrease in line voltage of at least 10% of the average line voltage for half a cycle or longer. The power sag is often caused by large inductive equipment, e.g. photocopy, bank of fluorescent lights.  Sags can be caused by external factors as well, such as large power draining equipment used in other buildings.

Sags can be particularly detrimental to electronic equipment because of the malfunctions caused by the sudden decrease of available voltage to the power supply. Relays and solenoids can chatter generating spikes. Complete failure rarely occurs, however equipment lockup or lockout can occur requiring a resetting process.

Often equipment continues to operate, with the user, unaware of any problems that may have occurred.

Surge

A power surge is the opposite of a sag and is often referred to as ‘High Line Voltage’.   A surge is defined as an increase in line voltage above 253 volts (on a 230V Line) for a half cycle or longer. Like the sag, the power surge is often caused by large inductive loads being applied on the same line. Power surges can cause some of the most dangerous situations, and their resulting damage is most difficult to repair.

Direct Relationship

There is a direct relationship between the amount of protection provided, the cost for that level of protection, and the price it is to replace the items destroyed.  Furthermore, there is a convenience factor.  How easy is it to replace and rewire the damaged component verses the cost of protection.

Almost 'Spiritual' Protection

Some manufacturers of surge protectors often claim almost ‘spiritual’ protection; however, not every board is identical in the level of protection offered.

LEFT:  A generic extension board featuring back lit on/off button and a red LED, that when illuminated, instils confidence in the words 'surge protected'.  This particular board does not have any form of surge protection and is not protected by a internal circuit breaker.

Inexpensive surge boards may only work once, and then not provide any indication to whether they have been damaged.  Recall that many surges are invisible and only the surge protector will know a surge has occurred.  

Other protectors do not provide high level protection, meaning that your equipment will be protected by a minor power surge, but not by a higher or continuous surge.

Many inexpensive power extension boards sport on their faceplate the writing ‘surge protected’.  These boards are nothing more than glorified power boards and are not suitable for the protection of delicate equipment against any form a power surge.

Circuit Breakers Verses Surge Protection

A circuit breaker will provide an initial level of protection against a power surge – provided the circuit breaker trips, does not malfunction, and the intensity of the power surge is great enough to trigger the circuit breaker.  However, a circuit breaker is NOT designed to filter electrical noise or minor power surges – these electrical imbalances will not trigger a circuit breaker and the electricity will travel to the power point and onward to any equipment attached to the power point.  As discussed earlier, minor power surges are responsible for shortening the life of many components.

It should be remembered that although a circuit breaker will probably be triggered during a high volume or continuous power surge, the breaker may not trigger if the power surge is minimal.  It also worth remembering that a circuit breaker does not trip immediately a power surge enteres its circuit.  There is a millisecond or two delay.  This delay can be enough for power to travel through the circuit breaker to any delicate equipment attched to a power point.

A circuit breaker is designed to trigger when there is an over amperage above the circuit breaker's rating.  it protects the wires from over-amperage and overheating and potential for fire to occur.  A surge protector - which may also incorporate a circuit breaker,  is designed to protect/filter against power surges.  Although both pieces of equipment are similar, there end uses are different.

I have used, for several years, surge protectors manufactured by Belkin.  In general they were reliable and each unit provided two LED lights to warn if the device was not working.  However, Belkin protectors have a limited life time based on their Joule reservoir, which in moderately priced units is around 525 Joules.

Novaris Tasmania

Considering the expense and the amount of time that has been expended into building the simulator, I decided to up the ante and purchase a more solid and reliable system to protect against possible unwanted power surges, noise and spikes.  

LEFT:  Novaris PP10A/4 surge filter.  Simple LEDs indicate functionality of the unit while a push to reset circuit breaker button is located on the side of the unit.  4 power points facilitate connection of plugs or extension boards.

Novaris Tasmania sounds more in-line with something Stephen Hawkens has recently discovered and named in a far away galaxy; however, the name belongs to a Tasmanian company that develops and manufacturers surge protection equipment explicitly for industries that operate delicate equipment.

Two PP10A(4) surge filters manufactured by Novaris in Tasmania, Australia were commissioned.   For those more technically or theoretically inclined, the PP10A/4 specification sheet can be read here.  

The simulator, with everything operational, draws very close to 10 amps; therefore, to stop the possibility of the household circuit breaker tripping if the 10 amp boundary is crossed, various simulator sectors are connected to two power points in two power zones.  At each power point I have installed a PP10A/4.  

The PP10A/4 enables four extension boards to be attached, which between two units, is more than enough to ensure that everything in the simulator is protected.

Complete Protection - Modems and Routers

Often forgotten is the need to also protect against unwanted noise and surges that may be transmitted along copper wires from the telephone line to the router, modem and switch box (assuming the simulator is connected to the Internet).

This may or not be an issue depending upon the type of wiring that has been used – older style copper wires have good conductivity; therefore, these wires will transmit the effects of a power surge; however, modern glass wire has minimal conductivity which lessons the opportunity for electricity to migrate.

Many surge protectors also provide protection in this area; however, as stated earlier the effectiveness of any surge protector to protect against unwanted power surges is dictated by its Joule reservoir.

Future Post

This post has focused, in the simplest terms, on the concept of household power distribution and the need for some type of surge protector.  In a future post, I will discuss other methods of protecting delicate components from unwanted surges in power – in particular how to protect interface cards from damage from internal power spikes caused by computer power supply failures, reverse spiking, and grounding issues.

1 Murdering is a term used in the computer industry to describe when a process is stopped suddenly (such as turning the power off) without allowing the correct closing procedure to be followed.

Tuesday
Dec012015

Major Differences Between Classic and Next Generation Throttle Quadrants

The advent of high quality reproduction parts in association with advanced avionics suites produced by companies such as ProSim-AR and Sim Avionics, has led many flight simulator enthusiasts to strive closer to Microsoft’s claim ‘as real as it gets’.

LEFT:  There is little mistaking the tell-tale white-coloured handles and skirts of the Next Generation Throttle. (click to enlarge).

The availability of real parts formally used in classic airframes has never been greater, and many enthusiasts are purchasing various parts and converting them to flight simulator use.

The ‘holy grail’ of conversion has always been the Boeing throttle unit, and depending upon individual requirements, many older style throttle units have been retrofitted to appear very similar, if not near-identical, to their Next Generation counterparts.

This article will compare and contrast the major differences between the Boeing 737 classic throttle and the Next Generation throttle.  The word classic is usually used to refer to airframes belonging to the 200, 300, 400 and 500 series.  The Next Generation (NG) refers to the Boeing 600, 700, 800 and 900 series.

Historical Context

The throttle quadrant observed in a modern airliner has relatively old roots. 

LEFT:  Boeing 727-100 throttle quadrant.  Although there are obvious differences in that the 727 has three engines, the overall design and appearance of the quadrant is very similar to its modern counterpart.  Image copyright to Keven Walchler (click to enlarge).

The forbearer of the NG throttle was designed in the late 50's and early 60's and was initially used in the B707.  As aircraft types evolved, throttle design remained relatively static with similar-designed throttles being used in the Boeing 727, 717 and 737 series aircraft.

The B737-100 made its debut in April 1968, to be followed shortly by the 200 series with a slightly longer fuselage.  During the 1980’s Boeing released the classic series of airframes from the 300 through to the 500 series. 

During this time, the technology altered little and the design of the throttle quadrant reflected the ability of Boeing to reuse existing technology with minimal alterations.  This principle of reuse can save a company millions of dollars in redesign and development costs.

This Goes With That (Compare and Contrast)

The Boeing 737-800 NG is the airframe that many enthusiasts strive to duplicate in a flight simulator.  However, Next Generation parts are difficult to find and when found are expensive to procure.  Fortunately, for the simulation community, a throttle unit will function correctly within flight simulator no matter what airframe the throttle originated.

Many of the nuances between a classic and NG throttle quadrant are subtle and for the most part only the more knowledgeable will notice.  

The more obvious highlights of the NG are the white-coloured thrust lever shrouds, TOGA button assembly, flaps arc, speedbrake lever knob, and the moulded white-coloured side panels and panniers.  Whilst it is possible to alter many of the attributes of a classic throttle to conform with those of an NG, not every part can be easily transformed.  For example, the flaps arc between the classic and NG is very different in design and appearance and cannot be retrofitted.

TABLE 1 provides an overview to the main visual differences between the classic and NG throttle quadrants (courtesy Karl Penrose who kindly allowed the use of photographs taken of his 600 series throttle).  Note that there may be other subtle differences, some visual and others in design/operation.  The table does not address the center pedestal as pedestals vary greatly between airframes.  Retrofit 1 refers to the level of difficulty it is to make the classic throttle appear similar to the NG unit.

1 The words 'level of difficulty' is subjective; it depends on numerous factors such as experience and knowledge – neither of which is identical between individuals.

Final Call

The differences between a classic and NG throttle unit are largely cosmetic with some subtle design and operational differences.  Retrofitting a classic unit to appear similar to a Next Generation throttle is possible, however, there will be some aesthetics that will probably not be altered, such as the speedbrake lever knob, stab trim indicator tabs, side mouldings, paniers and flaps arc.  

This said, the ability to use an OEM throttle unit, no matter from which airframe, far supersedes any reproduction unit on the market.  OEM throttles are sturdy, robust and well-built.  Unless you do something particularly foolish, you will not damage an OEM throttle.

BELOW:  Two image galleries showing the various differences between the classic and Next Generation throttle quadrants.  Thanks to Karl Penrose who kindly allowed the use of photographs taken of his 600 series throttle.  To stop the slideshow, click the image and navigate by the numbered squares beneath the image.

B737 Classic Series Throttle Quadrant


B737 Next Generation (NG) Series Throttle Quadrant

Friday
Nov062015

Control Wheel Steering (CWS) Explained

CWS is the acumen for Control Wheel Steering.  Broadly speaking, it is a sub-set of the autopilot (A/P) system which can used on either System A or B.  When engaged, CWS maneuvers the aircraft in response to control pressures applied to the control wheel or column.

LEFT:  B737 Mode Control Panel (MCP) showing location of CWS buttons on Collins unit .  The CMD and CWS buttons are located on the First Officer side of the MCP.  Each of the four press to engage buttons has a green annunciator which illuminates when the mode is engaged.

The control pressure is similar to that required for manual flight. When control pressure is released, the autopilot holds the existing attitude until CWS is disengaged, or the autopilot is engaged. 

The Flight Crew Training Manual (FCTM) states:

‘Control Wheel Steering (CWS) may be used to reduce pilot workload. Follow the manually flown procedure but instead of disengaging the autopilot, engage CWS.’

CWS is a similar system to the ‘Fly By Wire’ system utilized by Airbus.

CWS Benefits

The obvious advantage in using CWS is that you do not have to continually apply positive pressure on the yoke and control column to maintain a set pitch or roll.  The control pressures on the flight controls are in the order of 37 pounds push/pull value +- 3 pounds and continually applying this pressure for a protracted period of time can be tiring.

Additionally, CWS enables you to fly the aircraft using the flight controls, rather than turning the heading knob on the Mode Control Panel (MCP) or configuring other automated processes such as Level Change, Vertical Speed, VNAV, etc.  Being able to ‘feel’ the control surfaces through the yoke and column has obvious benefits that flying using the MCP cannot convey.

CWS is also advantageous when flying in turbulent conditions (additional information below) as it results in smoother transitions than when the autopilot is used.  CWS also allows for greater control of the aircraft when performing touch and goes and circuits at lower altitudes.

Practical Example

CWS is often used during the climb to altitude, with the A/P being engaged at 10,000 feet.  

LEFT: PFD with CWS engaged during climb following flaps retraction.  FMA displays CWS R & CWS P, vertical speed is 2650 and pitch mode is V/S after changing from TOGA thrust following climb out.  Pitch and roll follows the FD bars and speed is 240 with altitude set to flight level 20900.  If CWS remains engaged, the aircraft will continue at this attitude.  Of importance is that the airspeed is NOT protected in certain modes.  In other words, if the attitude is altered, the airs[peed may increase or decrease accordingly without autothrottle intervention.

Following rotation, the Flight Director (FD) bars will be followed maintaining V2+15/20 until Acceleration Height (AH) is reached.  At AH, the MCP speed will be increased to climb speed, or to a constraint if required by Air Traffic Control.  As airspeed increases the flaps will be retracted.  When the flaps are retracted, the control column will be placed in a position that correlates to the Flight Director bars and CWS A or B will be engaged – the attitude of the aircraft will now be fixed.  

The aircraft, in TOGA thrust, will maintain the established pitch as it ascends to the altitude set on the MCP.  TOGA thrust is speed protected; therefore, as long as the FD bars are followed there will not be a speed incursion.  If a roll mode is selected, the navigational data provided by this mode is also supplied to the Flight Director.  Once the desired altitude has been reached, LNAV / VNAV is engaged.

Whether a flight crew used CWS is personal preference and some flight crews use it regularly while others have never used it.

Turbulence (autopilot or CWS)

The Flight Crew Training Manual (FCTM) states:

‘That during times of turbulence the A/P system (CMD A/B) should be disengaged.’

The reason that CWS is beneficial when flying in turbulence is that the A/P (unless it was engaged in CWS) is attempting to maintain an attitude (pitch) that is based upon a predefined barometric pocket of air that is at your altitude or flight level.   In severe turbulence, this pocket of air may not be stable which will result in the autopilot seeking to change altitude or, at its worse disconnecting.

In turbulence, this is exactly what you want to try and avoid and is the reason engaging CWS is important.  If CWS is engaged, it will maintain an attitude rather than the A/P attempting to match the attitude to the possible changing barometric pressure.

Flight Crew Training Manuals differ in their content as each manual has been written with a particular airline in mind.  Many virtual flyers duplicate the procedures followed by Ryanair.  Documentation for Ryanair is relatively easy to find and the policy of this airline is reasonably conservative.  As such, I have transcribed from the Ryanair FCTM the segment on the use of CWS during turbulence.

The Ryanair FCTM states:

‘Flight through severe turbulence should be avoided, if possible.  When flying at 30,000 feet or higher, it is not advisable to avoid a turbulent area by climbing over it unless it is obvious that it can be overflown well in the clear.  For turbulence of the same intensity, greater buffet margins are achieved by flying the recommended speeds at reduced altitudes.  Selection of the autopilot Control Wheel Steering (CWS) is recommended for operation in severe turbulence’.

The recommended Ryanair procedures for flight in severe turbulence are:

•    Do not use Altitude Hold (ALT HLD) mode.

•    Airspeed - Target airspeed should be approximately 280 KIAS or 0.76 MACH, whichever is lower.

•    Severe turbulence will cause large and often rapid variations in indicated airspeed.  Do not chase the airspeed.

•    Yaw Damper – Engaged.

•    Autopilot - Optional - If the autopilot is engaged, use CWS position, do not use ALT HLD mode.

•    Autothrottle – Disengage.

•    Attitude - Maintain wings level and the desired pitch attitude. Use the attitude indicator as the primary instrument. In extreme drafts, large attitude changes may occur.  Do not use sudden large control inputs.  After establishing the trim setting for penetration speed, do not change the stabilizer trim.

Technical Data (general)

The Mode Control Panel (MCP) has two CWS buttons located on the First Officer side of the MCP beside the CMD A and CMD B buttons.  Like the autopilot, CWS has a redundancy system (system A or system B).  By default CWS A and CWS B buttons are off and must be depressed to engage either system.  

When engaged the annunciator will illuminate green and the Flight Mode Annunciator (FMA) on the Primary Flight Display (PFD) will annunciate CWS P and CWS R.

CWS can only be engaged when there is no pressure on the flight controls.  Therefore; the method to engage the system is to depress one of the two CWS buttons and then position the flight controls where you want them.  The system will then maintain the pitch/roll attitude until either the flight controls are moved, the autopilot is engaged (CMD A or CMD B), or CWS is disengaged by depressing the CWS button.

CWS cannot be engaged when any of the following conditions are met:

•    Below 400 feet.
•    Below 150 feet RA with the landing gear in the down position.
•    After VOR capture with TAS 250 kt or less.
•    After LOC capture in the APP mode.

The Flight Crew Training Manual states:

‘After autopilot engagement, the airplane may be manoeuvred using the control wheel steering (CWS) pitch mode, roll mode, or both using the control wheel and column. Manual inputs by the pilot using CWS are the same as those required for manual flight. Climbs and descents may be made using CWS pitch while the roll mode is in HDG SEL, LNAV or VOR/LOC. Autopilot system feel control is designed to simulate control input resistance similar to manual flight.

Methods of Operation

There are three main methods of operation; however, the detail can blend and easily become confusing.  The following information has been edited from documentation acquired from Smart Cockpit Airline Training.

1:  CWS A/B Engaged or CWS A/B Annunciator Illuminated.

•    Depressing the CWS A/B button on the MCP engages the A/P pitch and roll axes in the CWS mode and displays CWS P and CWS R on the FMA on both the Captain and First officer Primary Flight Displays (PFD).

•    With CWS engaged, the A/P maneuvers the aircraft in response to control pressures applied to the control wheel or column. The control pressure is similar to that required for manual flight. When control pressure is released, the A/P holds existing attitude.
•    Smartcockpit.com BOEING 737 SYSTEMS REVIEW Page 4
•    If column pressure is released with bank angle 6 degrees or less, the A/P rolls the wings level and holds existing heading. This feature is inhibited when any of the following conditions are met:

1.    Below 150 ft RA with the landing gear down.
2.    After F/D VOR capture with TAS 250 kt or less.
3.    After F/D LOC capture in the APP mode.

2:  CWS Pitch on FMA in CMD A/B or CMD A/B Annunciator Illuminated.

The pitch axis engages in CWS while the roll axis is in CMD when:

•    A/P pitch has been manually overridden with control column force. The force required for override is greater than normal CWS control column force. This manual pitch override is inhibited in the APP mode with both A/Ps engaged.

•    A command pitch mode has not been selected or was deselected.

•    Command pitch modes can then be selected and CWS P is annunciated on the Flight Mode Annunciators while this mode is engaged.

•    When approaching a selected altitude in CWS P with the A/P in CMD, CWS P changes to ALT ACQ and, when at the selected altitude, ALT HOLD engages.

•    If pitch is manually overridden while in ALT HOLD at the selected altitude, ALT HOLD changes to CWS R If control force is released within 250 ft of the selected altitude, CWS P changes to ALT ACQ and the A/P returns to the selected altitude and ALT HOLD engages.  If the elevator force is held until more than 250 ft from the selected altitude, pitch remains in CWS PITCH.

3:  CWS Roll on FMA in CMD A/B or CMD A/B Annunciator Illuminated.

The roll axis engages in CWS while the pitch axis is in CMD when:

•    A/P pitch has been manually overridden with control column force. The force required for override is greater than normal CWS control column force.  
•    A command roll mode has not been selected or was deselected.

•    Command roll modes can then be selected and CWS R is annunciated on the Flight Mode Annunciators while this mode is engaged.

•    CWS R with an A/P engaged in CMD can be used to capture a selected radio course while the VOR/LOC or APP mode is armed. Upon intercepting the radial or localizer, the F/D and A/P annunciation changes from CWS R to VOR/LOC engaged and the A/P tracks the selected course.

Final Call

The use of CWS is very much underused and underappreciated.  Although surface control loading in a simulator rarely matches that of a real aircraft, the use of CWS in a simulator environment can still have positive benefits equating to better aircraft handling, especially when flying circuits and flying in turbulence.

Saturday
Oct032015

B737 NG Display Unit Bezels By Fly Engravity 

I recently upgraded the display unit bezels (frames) on the Main Instrument Panel (MIP).  

LEFT:  The bezels that have replaced the acrylic bezels made by FDS. The landing gear, clock annunciators (korrys) and brake pressure gauge are OEM parts converted for flight simulator use - First Officer side (click to enlarge).

The previous bezels, manufactured by Flight Deck Solutions (FDS), lacked the detail I was wanting.  Increasingly, I found myself being fixated by glaringly incorrect hallmarks that did not conform to the original equipment manufacturer (OEM) – in particular, the use of incorrectly positioned attachment screws, the lack of a well-defined hinge mechanism, and the use of acrylic rather than aluminum.

Although it is not necessary to have replicated items that conform to a real part, it does add to the immersion level, especially if you are using predominately OEM parts.  The MIP in my case is pruelly a skeleton on which to 'hang' the various real aircraft parts that have been converted for flight simulator use. 

This is not a review, but more a reason to why sometimes there is a need to change from one product to another.

OEM Display Units

The OEM display units used in the Boeing Next Generation airframes comprise a large rectangular box that houses the necessary avionics and glass screen for the display.   

LEFT:  The OEM display is a solid unit that incorporates the avionics, display and bezel in the one unit.  This unit has the protective plastic attached to the screen.

The display unit is mounted by sliding the box into the MIP along two purpose-built sliding rails.  The unit is then locked into the MIP by closing the hinge lever and tightening the thumb screw on the lower right hand side of the bezel.  The hinge mechanism is unique to the OEM unit in that once the thumb screw is loosened; one side of the lower display adjacent to the hinge becomes a lever in which to pull the unit free of its locking points in the MIP.

The units are usually manufactured by Honeywell.

The display unit is one piece which incorporates the bezel as part of the assembly; therefore, it is not possible to obtain just the bezel – this is why a reproduction is necessary.

Reproduction Bezels

Reproduction bezels are manufactured by several companies – Open Cockpits, SimWorld, Fly Engravity and Flight Deck Solutions to name a few.  As with all replica parts, each company makes their products to differing levels of accuracy, detail and quality.

I looked at several companies and the closest to the  OEM item appeared to be the bezels manufactured by Fly Engravity and CP Flight (CP Flight are a reseller of Fly Gravity products).  

The main reasons for changing-out the FDS bezels were as follows:

  • FDS bezels have two Philips head screws in the upper left and right hand side of the bezel.  These are used to attach the bezel to the MIP.  The real bezel does not have these screws.
  • FDS bezels are made from acrylic.  The bezels in the real B737, although part of a larger unit, are made from aluminum.  Fly Engravity make their bezels from aluminum which are professionally painted with the correct Boeing grey.  
  • FDS have not replicated the hinge in the lower section of the bezel.  Rather, they have lightly engraved into the acrylic a facsimile of the hinge .   Fly Engravity fabricate a hinge mechanism, and although it does not function (there is absolutely no need for it to function) it replicates the appearance of the real hinge.
  • FDS use 1mm thick clear Perspex whereby the real aircraft uses smoke grey-tinted glass.  Fly Engravity bezels use 3 mm smoke grey-tinted Perspex.
  • The Perspex used by FDS is very thin and is attached to the inside of the bezel by double-side tape.  The thinness of the material means that when cleaning the display it is quite easy to push the material inwards which in turn breaks the sticky seal between the Perspex and the inside of the bezel.  Fly Engravity use thicker Perspex that is attached to the inside of the bezel by four screws.  It is very solid and will not come loose.

Table 1 provides a quick reference to the assailant points.

 

Attaching the Bezels to the FDS MIP

The FDS and Fly Engravity bezels are identical in size; therefore, there is not an issue with the alignment of the bezels with MIP – they fit perfectly.

LEFT:  Detail showing the hinge mechanism in the Fly Engravity bezel.  Although the hinge is non-functional, the detail and depth of the cut in the aluminium frame provides the illusion of a functioning hinge mechanism (cilck to enlarge).

Attaching the Fly Engravity bezels to the FDS MIP is not difficult.  The Fly Engravity bezels are secured to the MIP using the same holes in the MIP that were used to secure the FDS bezels. However, the screws used by Fly Engravity are a larger diameter; therefore, you will have to enlarge the holes in the MIP.  

 

For the most part the holes align correctly, although with my set-up I had to drill two new holes in the MIP.

LEFT: Detail of the hinge thumb knob on the Fly Engravity bezel.  Although the internal screw is missing from the knob, the cross-hatched pattern on the knob compensates.  The knob is screwed directly into the aluminium frame and can be loosened or tightened as desired.  The circular device is a facsimile of the ambient light sensor (click to enlarge).

The Fly Engravity bezels, unlike the FDS bezels, are secured from the rear of the bezel via the backside of the MIP.  The bezel and Perspex have precut and threaded holes for easy installation of the thumb screws.

LEFT:  Cross section of the Fly Engravity bezel showing the detail of the Perspex and attachment screw (click to enlarge).

Upgrade Benefits - Advantages and Disadvantages

It depends – if you are wishing to replicate the real B737 MIP as much as possible, then the benefits of upgrading to a Fly Engravity bezel are obvious.  However, the downside is that the aluminum bezels, in comparison to acrylic-made bezels are not inexpensive.

The smoke grey-tinted Perspex has definite advantages in that the computer monitor screens that simulate the PFD, ND and EICAS appear a lot sharper and easier to see.  But a disadvantage is that the computer monitors colour calibration alters a tad when using the tinted Perplex.  This is easily rectified by calibrating your monitors to the correct colour gamut.  I was concerned about glare and reflections, however, there is no more using the tinted Perspex than there is using the clear Perspex.

The Fly Engravity bezels have one minor inaccuracy in that the small screw located in the middle of the hinge thumb knob is not simulated.  This is a small oversight, which can be remedied by having a screw fitted to the knob.

Improvements

A possible improvement to the Fly Engravity bezels could be to use flat-headed screws, or to design a recessed head area into the rear of the Perspex (see above photograph which shows the height of the screw-head).  A recessed area would allow the screw head to sit flush enabling the monitor screen to be flush with the rear of the Perspex. 

The inability of the monitor screen to sit flush with the Perspex does not present a problem, but it is good engineering for items to fit correctly.

Final Call

Although the bezels made by FDS do not replicate the OEM item, they are still of good quality and are functional.  However, if you are seeking authenticity and prefer an aluminum bezel then those produced by Fly Engravity are superior.

Endorsement and Transparency

I have not been paid by Fly Engravity or any other reseller to write this post.  The review is not endorsed and I paid full price for the products discussed.

Glossary

EICAS – Engine Indicator Crew Alert system.
MIP – Main Instrument Panel.
ND – Navigation Display.
OEM – Original Equipment Manufacturer (aka real aircraft part).
Perspex - Poly(methyl methacrylate), also known as acrylic or acrylic glass as well as by the trade names Plexiglas, Acrylite, Lucite, and Perspex among several others.
PFD – Primary Flight Display. 

Friday
Sep182015

New Interface Module Installed - SMART

The installation of an OEM flaps gauge to the simulator was the catalyst to the design and development of an additional interface module. 

The module, called 'SMART' is a platform to accommodate the various components necessary to configure and drive the flaps gauge.

LEFT:  OEM Flaps gauge installed to Main Instrument Panel (MIP).  A new interface module was designed to incorporate the 400 hertz needed to power the gauge.  Furthermore, SMART is also responsible for the interface a several other OEM gauges.

SMART has also been used to accommodate the interface cards necessary to use the OEM AFDS units, Autobrake Selector knob and the Used Fuel Toggle.

The SMART module has been discussed in a separate section as a subset to the Interface Module section.

Updates

Also of note, is that the throttle page, a subset of the Flight Control pages (main menu) has been updated.

The page now refers to the most recent throttle quadrant used in the simulator.  There is also a internal links section, at the bottom of the page.

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