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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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Entries in B737-800 Boeing Flight Simulator (17)

Thursday
Dec132018

Using OEM Panels in the MIP

The introduction of the Boeing 737 Max has meant that many carriers are updating their fleets and retiring earlier production 737 NG airframes.  This has flow on benefits for flight simulator enthusiasts, because more and more OEM NG parts are becoming available due to NG airframes being stripped down and recycled.  

LEFT:  OEM Captain-side DU panel.  Note the thick engraving and specialist DZUS fasteners (click to enlarge).

Although some items, such as high-end avionics are priced outside the realm of the average individual, many other parts have become reasonably priced and are often a similar price to the equivalent reproduction part.

This article primarily relates to the panels used in the Main Instrument Panel (MIP), and lower kick stand.  The term panel means the aluminum plate that is secured to the framework of the MIP, and lightplate refers to the engraved plate that is secured to the panel.

Do You Notice The Difference

This is a common question.  The resounding answer is yes – the difference between OEM and reproduction parts can be noticed, especially if you compare the identical parts side by side.  This said, some high-end companies manufacturer panels that are almost indiscernible from the OEM panel.  These panels are bespoke, expensive, and usually are only made to a custom order.  Therefore, it really depends on which manufacturer/company you are comparing the OEM panel against.

By far the biggest difference between an OEM and reproduction panel, other than appearance, is the tactile feel of a knob, the overall robustness of the panel, and the firmness felt when rotating a commercial-grade switch; the later feels very accurate in its movement. 

LEFT:  Close up detail of OEM lightplate and general purpose knobs (click to enlarge)

There is litle compromise with backlighting as an OEM panel has a consistent colour temperature and intensity without hot and cold spots.  

Using a real panel helps to provide immersion and, as your're using a real aircraft part there is no second-guessing whether the panel is an accurate copy; using an OEM panel is literally 'as real as it gets'.  Furthermore, it’s  environmentally friendly to use second hand parts.  New parts (reproduction or otherwise) are made from  finite resources. 

Limitation

Not every OEM part can work in a home simulator.  For example, the OEM potentiometer responsible for the dimming function in the lower kickstand DU panels cannot be used.  This is because Boeing use a rheostat instead of a potentiometer.  Without going into detail, a rheostat is designed to take into account 115 volts AC commonly used in aircraft.  If using these panels. you will need to change the rheostat to a high-end commercial potentiometer.  

Table 1 outlines 'some' of the main differences between the OEM panels and their reproduction equivalents.

Table 1:  Main differences between OEM and reproduction panels (MIP only).

The information presented in the above table, should not be taken in a way that reflects poorly on the manufacturer of reproduction panels.  There are a few high-end companies whose panels are indiscernible from the real item; it’s the purchaser’s knowledge and the manufacturer’s skill that will define whether a reproduction panel replicates the real item.   ‘Caveat Emptor’ should always be at the forefront of any purchase decision.

Potential Problems Using OEM Panels in the MIP

Potential problems often surface when attempting to mate OEM parts to the framework of the MIP.  This is because reproduction MIPs rarely echo the identical dimensions of their OEM counterpart. 

It's not possible to document every potential problem, as all reproduction MIPs are slightly different to each other.  However, some issues encountered may be the misalignment of screw holes between the MIP framework and the OEM panel, the inability to use the panel's DZUS fasteners, the panel being too large or too small for the MIP in question, and the open framework structure at the rear of the panel (which incorporates the wiring lume and Canon plugs) interfering with the infrastructure of the reproduction MIP, or the mounting of the computer screens.

In general, OEM panels cannot be mounted to a reproduction MIP without major work being done to the framework of the MIP.   The solution is to use a MIP that has been designed 1:1 with the OEM MIP, or fabricate a MIP in-house to the correct dimensions.

Specifics to the FDS MIP

The MIP used in the simulator is manufactured by Flight Deck Solutions (FDS), and although the MIP is made to a very high quality, the dimensions of the MIP are not 1:1. 

LEFT:  OEM Stand-by instrument panel. Although difficult to see from a picture, the overall robustness of this panel surpasses all but the very best reproductions (click to enlarge).

The most problematic issue is that the MIP length is slightly too narrow to enable the OEM panels to be fit correctly to the front of the framework.  For example, the OEM chronograph panel is 1 cm wider than the FDS chronograph panel.  Furthermore, most of the OEM panels (such as the standby instrument, chronograph and landing gear panel) measure 130 mm in height as opposed to the FDS panels that measure 125 mm in height.  This causes problems when trying to line up the bottom of each panel with the bottom of the display bezels

The standby instrument panel does fit, however, there is a few centimeters of space between the panel and the adjacent display bezel frame.  In the real aircraft, the display bezel and the edge of the standby instrument panel almost abut one another.  The autobrake panel does fit as do the lower kickstand panels.

FDS use screws to attach their panels to the upper MIP framework, however, OEM panels use DZUS fasteners.  The screw holes on the FDS MIP do not align with the position of the DZUS fasteners in the OEM panel.  The lower MIP panel (kickstand) in the real aircraft also incorporates a DZUS rail to which the panels are attached.  The FDS kickstand does not use a DZUS rail, and screws or reproduction DZUS fasteners are needed to secure the OEM kickstand panels.

The above said, FDS does not state that their MIP is I:1, and when asked will will inform you that OEM panels will not fit their products without considerable fabrication.

Specialist DZUS Fasteners

The OEM panels used in the upper MIP incorporate into the panel a specialist DZUS fastener.  This fastener is used to tightly secure the panel to the framework of the MIP; screws are not used.  Screws are only used to secure the lightplate to the panel. 

LEFT:  DZUS fastener that secures DU panel to the MIP framework (click to enlarge).

The DZUS fastener is shaped differently to the fasteners used to secure the panels located in the lower kickstand, overhead and center pedestal, and these parts are not interchangeable. 

Reproductions rarely replicate these DZUS fasteners.  However, like many things it's often the small things that make a difference (at least aesthetically).

LEFT:  Rear of OEM Captain-side DU panel.   Note heavy duty rotary switches (Cole & Jaycor brand), neat and sturdy wiring lume, and easy connect Canon plug.  The use of the correct bracket in the panel enables the AFDS unit to fit snugly to the panel.  Note the depth of the external frame which can cause placement issues (click to enlarge).

Advantages Using OEM Wiring Lume and Canon Plugs

A major plus using any OEM panel is that the part usually includes an expertly-made wiring lume that terminates at Canon plug.    If possible, the original wiring lume should be kept intact and additional wiring should be done from the Canon plug.  It’s very difficult to duplicate the same level of workmanship that Boeing has done in relation to the wiring.  Furthermore, the wire that has been used is high-end aviation grade wire.

The Canon plug deserves further mention, as the use of a Canon plug (or any connector for that matter) enables you to easily remove the panel for service work should this be required.  If at all possible, the original Canon plug (and wiring) should be used because it’s neat and tidy and ensures a good connection.  However, if the correct Canon plug cannot be procured then a reproduction plug should be fabricated.  There is nothing worse than having to disconnect wires from an interface card to remove a part.

Configuring an OEM Panel

Configuring an OEM panel to use in flight simulator depends on which panel you are referring to. 

LEFT:  OEM landing gear panel. Like any OEM part, the neatness in relation to the wiring is immaculate.  A Canon plug enables the panel to be connected to a lume which then connects with whatever interface card is in use (click to enlarge).

Panels with knobs, toggles and switches are relatively straightforward to interface with a respective interface card (Phidget card, PoKeys card, FDS SYS card or similar).  Determining the pinouts on the Canon plug that control backlighting requires the use of a multimeter, and then connection to a 5 volt power supply.  If the panel includes annunciators (korrys), then these will need to be connected to a 28 volt power supply (using the correct pinouts).

Technology is rarely static, and there are other ways to interface and configure OEM panels.  The ARINC 429 protocol is becomming inceasingly common to use along with specialist interface cards, and these will be discussed in separate articles.

The Future

The FDS MIP can, with some work, be modified to mount the OEM panels.  However, an easier option is to find another MIP that has been designed to mount the panels, or fabricate a MIP in-house to OEM dimensions.

LEFT:  Rear of DU panel showing korry connections and AFDS bracket (click to enlarge).

Final Call

Aesthetically, nothing beats the use of an OEM panel, and the panels used in the upper MIP and lower kickstand offer little comparison to their reproduction equivalents, with possible exception to bespoke reproductions. By far the biggest challenge is determining the pinouts for the Canon plug, but once known, configuration using a Phidget or other traditional card is relatively straightforward. 

As straightforward as it may seem, potential problems surface when attempting to mate OEM panels to an existing reproduction MIP.  To resolve these issues, often a replacement MIP is needed that has been made to the identical dimensions of the OEM counterpart.

Additional Information

The following articles may provide further information in relation to using OEM parts.

Note that some of these articles are to be reviewed and brought up-to-date (technology and ideas are rarely static).

Acronyms

ARINC 429 - Aircraft communication protocol
DU - Display Unit
Lume - A harness that holds several wires in a neat way
OEM - Original Equipment Manufacturer
MIP - Main Instrument Panel

Friday
Nov172017

Sounds Reworked - Flight Sim Set Volume (FSSV) - Review

Immersion is a perception of being physically present in a non-physical world.  The perception is created by surrounding the user of the simulator in images, sound or other stimuli that provide an engrossing total environment.  When something does not replicate its real world counterpart, the illusion and immersion effect is degraded.

LEFT:  Engine sounds will be at their highest at takeoff.

Engine Sound Output

The sound output generated by a jet aircraft as heard from the flight deck is markedly different when the aircraft is at altitude.  This is because of differences in air density, temperature, the speed of the aircraft, drag, and thrust settings.  The noise emitted from the engines will always be highest at takeoff when full thrust is applied.  At this time, the noise generated from wind blowing over the airframe will be at its lowest.  At some stage, these variables will change and wind noise will dominate over engine noise.

As an aircraft gathers speed and increases altitude, engine sound levels lower and wind levels, caused by drag, increase.  Furthermore, certain sounds are barely audible from the flight deck on the ground let alone in the air; sounds such the movement of flaps and the extension of flight spoilers (speedbrake).

Being a virtual flyer, the sound levels heard and the ratio between wind and engine sound at altitude is subjective, however, a visit to a flight deck on a real jet liner will enlighten you to the fact that that Flight Simulator’s constant-level sound output is far from realistic.

Add On Programs

Two programs which strive to counter this shortcoming (using different variables) are Accu-Feel by A2A Simulations and FS Set Volume (FSSV).  This article will discuss the attributes of FSSV (Sounds Reworked).

Flight Sim Set Volume (FSSV)

FSSV is a very basic program that reads customized variables to alter the volume of sound generated from Flight Simulator.  The program is standalone and can be copied into any folder on your computer, however, does require FSUIPC to connect with Flight Simulator.  Wide FS enables FSSV to be installed on a client computer and run across a network.  

The following variables can be customised:

(i)     Maximum volume
(ii)    Minimum volume
(iii)   Upper mach threshold
(iv)   Lower mach threshold
(v)    Engine volume ratio

Each of the variables will alter to varying degrees the Mach, engine %N1, rounded engine speed and volume percentage.  

For the program to have effect it must be opened either prior to or after the flight simulator session is opened. 

LEFT:  FSSV pop-up screen showing customised variables (default) that can be set and current reads-outs for the simulator session (click to enlarge).

It’s an easy fix to automate the opening of the program to coincide with Flight Simulator opening by including the program .exe in a batch file

A pop-up window, which opens automatically when the program is started, will display the variables selected and the outputs of each variables.  If the window is kept open, the variables can be observed ‘on the fly’ as the simulation session progresses.  Once you are pleased with the effects of the various settings, a save menu allows the settings to be saved to an .ini file.  The pop-up window can then be set to be minimized when you start a flight simulator session.  

How FSSV Works

The program reads the sound output from the computers primary sound device and alters the various sound outputs based upon customized variables.  The program then lowers the master volume at the appropriate time to match the variables selected.  FSSV will only alter the sound output on the computer that the program is installed.  Therefore, if FSSV is installed to the same computer as Flight Simulator (server computer) then the sound for that computer will only be affected.

Possible Issue (depends on set-up)

An issue may develop if FSSV is installed on a client computer and run across a network via Wide FS, then the program will not only affect the sound output from the server computer, but it also will affect the sound output from the client computer.  

A workaround to rectify this is to split the sound that comes from the sever computer with a y-adapter and connect it to the line-in of another computer, or use a third computer (if one is spare).

In my opinion, it’s simpler to install and run the program via a batch file on the server computer that flight simulator is installed.  The program is small and any drop in performance or frame rates is insignificant.

Summary

The program, although basic, is very easy to configure and use - a little trial and error should enable the aircraft sounds to play with a higher degree of realism.  However, the level that you alter the variables to is subjective; it depends on your perception to the level of sound heard on a flight deck – each virtual flyer will his or her own perception to what is correct. 

The program functions with FSX and P3D flawlessly. 

Finally, If you are unhappy with the result, it’s only a matter of removing/deleting the folder you installed the program to, or close the program during your simulator session to return the sound levels to what they previously were.  FS Set Volume can be downloaded at no charge at http://forum.simflight.com/topic/81553-fs-set-volume/.  

Video

The below video is courtesy of the FSSV website.

Saturday
Jul092016

RNAV Approaches

My previous post provided of overview on RNAV and RNP navigation.  This article will explain what a RNAV approach is, provide incite to the operational requirements for a RNAV approach, and discuss specifically the RNAV (RNP) approach.  I will also briefly discuss Approach Procedures and Vertical Guidance (APV) and RNP/ANP values.

The operational criteria for RNAV approaches is complicated and not easy to explain.  There are a number of RNAV approaches (often different for differing areas of the globe) and each is defined by the accuracy of the equipment used in the execution of the approach.  As such, this article is not all encompassing and I encourage you to read other technical articles available on this website and elsewhere.

LEFT:  RNAV 07 L - one of several RNAV approach charts for Los Angeles International Airport (LAX).  The most important aspect of an RNAV approach is that it is a Non-Precision Approach (NPA).  Note the word GPS is written in the title of the approach plate.

RNAV Approaches - Background Information

The Global Positioning System (GPS) is the brand name owned by the US military.  Initially all RNAV approaches were GPS orientated, however, in recent years this has been updated to include Global Navigation Satellite System (GNSS) applications.  GNSS applications are not owned (or controlled) by the US military.  As such, RNAV approach charts often use the word GPS/GNSS interchangeably.

What is an RNAV Approach

The definition for an RNAV approach is 'an instrument approach procedure that relies on the aircraft's area navigation equipment for navigational purposes'.  In other words, a RNAV approach is any non ILS instrument-style approach that does not require the use of terrestrial navigation aids such as VOR, NDB, DME, etc. 

Rather than obtain navigational information directly from  land-based navigational applications, the aids for the approach is obtained from a published route contained within the aircraft's Flight Management System (FMS) and accessible to the crew by the Control Display Unit (CDU).   The  approach broardly uses signals that are beamed from navigational satellites orbiting the Earth to determine the position of the aircraft in relation to the information presented from the database.

All Boeing Flight Management Systems (FMS) are RNAV compliant and have the ability to execute a RNAV approach.

A RNAV approach is classified as a Non-Precision Approach (NPA).

Non-Precision Approaches (NPA)

Before writing further, a very brief overview of Non-Precision Approaches is warranted.

There are three ways to execute a Non-Precision Approach.

(i)   IAN (integrated Approach Navigation).   IAN is a airline customer option and makes a NPA similar to an ILS approach.  A separate article has been written that addresses IAN.

(ii)   Vertical Speed (V/S).  V/S is not normally used when flying a RNAV approach that uses positional information from the aircraft's database.  However, V/S can be used for other Non-Precision Approaches.

(iii)   VNAV (Vertical Navigation).  VNAV is the preferred method to execute a NPA provided the approach is part of the FMS database. 

(iv)   LNAV (Lateral Navigation).  LNAV is mandatory for all approaches that are GPS/GNSS/RNP based.

RNAV Approach Types

The following are RNAV approaches:

(i)    RNAV (GPS) approach;

(ii)   RVAV (RNP) approach;

(iii)  RVAV (RNP) AR approach; and,

(iv)  RNAV (GNSS) approach.

The RNAV (GNSS) approach covers an additional three possible types of approach with each identified by a different minima.  The approaches are:

(i)    RNAV (GNSS) LNAV;

(ii)   APV Baro VNAV approach;

(iii)  APV SBAS approach.

It's easy to become confused by the various types of RNAV approaches, however, the actual flying of a RNAV approach does not differ greatly between each approach type.  The main difference lies in the level of accuracy applied to the approach and the methods used to enable this accuracy that determines what minima can be flown.

Approach Procedures with Vertical Guidance (APV)

APV refers to any approaches which are designed to provide vertical guidance to a Decision Height (DH).  An APV approach is charactertised by a constant descent flight path, a stable airspeed, and a stable rate of descent.  They rely upon Performance Based Navigation.  For an overview of PBN please refer to my earlier post.

The difference between the two APV approaches is that the APV Baro VNAV approach uses barometric altitude information and data from the FMS database to compute vertical guidance.  in contrast the APV SBAS approach uses satellite based augmentation systems, such as WAAS in the US and Canada and EGNOS in Europe, to determine lateral and vertical guidance. 

I will now discuss RNAV approaches in general and specifically, the RNAV (RNP) approach.

Flying The RNAV (GNSS) Approach

The RNAV (GNSS) approach is designed to be flown with the autopilot engaged.  The recommended roll mode is LNAV or HDG SEL.  The preferred method for pitch is VNAV.  If LNAV and VNAV are engaged, the aircraft will fly the lateral and vertical path as determined by the FMS database; the route is displayed in the LEGS page of the CDU.

The aircraft uses the FMS database to determine its lateral and vertical path.  As such, it is very important that the RAW data published in the navigational database is not altered by the flight crew.  Furthermore, the data presented in the CDU should be cross-checked to ensure it is identical to that presented on the RNAV approach chart.

As discussed previously, a RNAV (GNSS) approach is classified as a Non-Precision Approach.  Therefore, minima is at the Minimum Descent Altitude (MDA).   It is good airmanship to add +50 feet to the MDA to reduce the chance of descending through the MDA.  If a RNAV (RNP) or APV approach is being flown, the minima changes from a MDA to a Decision Height (DH). Whatever the requirement, the minima will be annotated on the approach chart.

RNAV (RNP) Approaches

RNP stands for Required Navigation Performance which means that specific navigational requirements must be met prior to and during the execution of the approach.

There are two types of RNAV (RNP) approaches:

(i)   RNAV (RNP) approach; and,

(ii)  RNAV (RNP) AR approach.

Both approaches are similar to a RNAV (GNSS) approach, however, a RNAV (RNP) approach, with the use of various sensors and equipment, achieves far greater accuracy through the use of Performance Based Navigation (PBN), and can therefore be flown to a DA rather than a MDA.

LEFT:  LIDO chart (Lufthansa Systems) depicting the RNAV (RNP) 01 approach into BNE-YBBN (Brisbane Australia).  Note that this chart has a Decision Altitude (DA) rather than a Minimum Descent Altitude (MDA).  Chart courtesy of NaviGraph (click to enlarge).

RNP/ANP - How It Works

A RNAV (RNP) approach uses RNP/ANP which is the comparison between the Required Navigation Position (RNP) and the Actual Navigation Position (ANP).   If the data becomes erroneous such as from the loss of a GPS signal, the ANP value will exceed the RNP value.    The use of RNP/ANP enables greater accuracy in determining the position of the aircraft.

RNP/ANP Alerts

If an anomaly occurs between RNP and ANP one of two RNP alerts will be generated:

(i)    VERIFY POSITION - displayed in the scratchpad of the CDU; or,

(ii)   UNABLE REQD NAV PERF-RNP - displayed on the Navigation Display (ND) on the EFIS Map. 

It should be noted that different versions of CDU software will generate different alerts.  This is because newer software takes into account advances in PBN.  To determine which software version is in use, press IDENT from the CDU main page (lsk1L) and check OP PROGRAM.  ProSim-Ar uses U10-8a.

The variables for RNP/ANP can be viewed in the CDU in the POS REF page (page 3), the LEGS page when a route is active, and also on the Navigation Display (ND).

A second type of RNP approach is the RNAV (RNP) AR approach.  This approach enables you to have curved flight paths into airports surrounded by terrain and other obstacles. Hence why special aircraft and aircrew authorization (AR) is required for these approaches.  Other than AR and additional flight crew training, the approach is identical to the RNAV (RNP) approach.

Advantages of RNAV and RNAV (RNP) Approaches

The benefit of using a RNAV approach over a traditional step-down approach is that the aircraft can maintain a constant angle (Continuous Descent Final Approach (CDFA)) until reaching minima.  This has positive benefits to fuel savings, engine life, passenger comfort, situational awareness, and also lowers flight crew stress (no step-downs to be followed).   Additionally, it also minimises Flight Into Terrain (CFIT) events.

A further advantage is that the minimas for a RNAV approach are more flexible than those published for a standard Non-Precision Approach not using RNAV.  RNAV approach charts have differing descent minima depending upon the type of RNAV approach.

For example, if flying a RNAV (RNP) approach the MDA is replaced by a DH.  This enables a lower altitude to be flown prior to a mandatory go-around if the runway threshold is not in sight.  The reason that a RNAV (RNP) approach has a DH rather than a MDA (and its resulting lower altitude constraint) is the far greater accuracy achieved through the use of Performance Based Navigation (PBN).

Approach To Land Using RNAV

The following addresses the basics of what is required to execute a RNAV approach.

Prior to beginning the approach, the crew must brief the approach and complete needed preparations. These include, but are not limited to, the following items, which may be included in an approach review card or other type of briefing aid:

(i)     Equipment that must be operational prior to starting the approach;

(ii)    Selection of the approach procedure, normally without modifications from the aircraft's navigation database;

(iii)    For airplanes without Navigation Performance Scales (NPS), one pilot should have the map display in the 10 NM or less range.  This is to monitor path tracking during the final approach Segment;

(iv)    For airplanes with NPS, the map display range may be set as the crew desires;

(v)     TERR display selected on at least the Captain or First Officer side of the ND;

(vi)     The RNP progress page displayed on the CDU (as needed). For airplanes equipped with NPS, selection of the CDU page is at the crew's discretion;

(vii)    The navigation radios must be set according to the type of approach; and,

(viii)   If a RNAV (RNP) approach is being executed, ensure that there is no UNABLE REQD NAV PERF - RNP alert displayed before starting the approach.

In addition to the above, airline Standard Operational Procedures (SOPs) may require additional caveats, such as range rings to be set up on the ND to provide enhanced situational awareness (CDU FIX page).

Select the approach procedure from the arrivals page of the CDU and cross-check this data with that published on the approach chart, especially the altitude constraints and the Glide Path (GP).

If the Initial Approach Fix (IAF) has an ‘at or above’ altitude restriction, it may be changed to an ‘at’ altitude restriction using the same altitude. Speed modifications are allowed as long as the maximum published speed is not exceeded. No other lateral or vertical modifications should be made at or after the IAF.

Beginning the Approach

Select LNAV no later than the IAF. If on radar vectors, select LNAV when established on an intercept heading to the final approach course. VNAV PTH must be engaged and annotated in the Flight Mode Annunciator (FMA) for all segments that contain a Glide Path (GP) angle, as shown on the LEGS page, and must be selected no later than the Final Approach Fix (FAF) or published glide path intercept point.

Speed Intervention (INTV), if desired, can be used prior to the GP.  Good airmanship directs that the next lower altitude constraint is dialled into the MCP altitude window as the aircraft passes through the previous constraint.  When 300 feet below the Missed Approach Altitude (MAA) re-set the altitude window in the MCP to the MAA.

Final Approach using RNAV

When initiating descent on the final approach path (the GP), select landing flaps, slow to final approach speed, and do the landing checklist. Speed limits published on the approach chart must be complied with to enable adequate bank angle margins. 

At minima, or as directed by the airline's SOP, the autopilot followed by the autothrottle is disconnected and a visual 'hands on' approach made to the runway threshold.

Once established on final approach, a RNAV approach is flown like any other approach.

Final Call

The Boeing aircraft is capable of several types of Non-Precision Approaches, however, outside the use of ILS and possibly IAN, the RNAV approach enables an accurate glide path to be followed to minima.  While it's true that the differing types of RNAV approaches can be confusing due to their close relationship, the approach is straightforward to fly.

This short article is but a primer to understanding an RNAV approach.  Further information can be found in the FCTM, FCOM and airlines SOP.

In my next article we will look some of the possible 'gotchas' that can occur when using VNAV.

References

Flight Crew Training Manual (FCTM), Flight Crew Operations Manual (FCOM) and airline SOP.

Acronyms and Glossary

Annunciator – Often called a korry, it is a light that illuminates when a specific condition is met
ANP - Actual Navigation Position
APV - Approach Procedure with Vertical Guidance
CFIT - Continuous Flight Into Terrain
DME – Distance Measuring Equipment
FAF - Final Approach Fix
FCOM - Flight Crew Operations Manual (Boeing)
FCTM - Flight Crew Training Manual (Boeing)
FMA - Flight Mode Annunciator
FMC – Flight Management Computer
FMS – Flight Management System
Gotcha - An unfavorable feature of a product or item that has not been fully disclosed or is not obvious.
GPS – Global Positioning System
GNSS - Global Navigation Satellite System
IAF - Initial Approach Fix
Korry - See annunciator
LNAV – Lateral Navigation
LPV - Localizer Performance with Vertical Guidance
MAA - Missed Approach Altitude
MCP – Mode Control Panel
ND – Navigation Display
NPA - Non Precision Approach
PBN - Performance Based Navigation
RNAV – Area Navigation
RNP - Required Navigation Performance
SOP - Airline Standard Operational Procedure.  A manual that provides additional information to the FCTM and FCOM
SBAS - Satellite based augmentation systems.  In the U.S. called WAAS and Europe called EGNOS.
VNAV – Vertical Navigation
VNAV PTH – Vertical Navigation Path
VNAV SPD – Vertical Navigation Speed
VOR – VHF Omni Directional Radio Range

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. 

Saturday
Aug012015

Throttle Quadrant Rebuild - New Wiring Design and Rewiring of Center Pedestal 

Put bluntly, the wiring in the center pedestal was not to a satisfactory standard.  Several panels were daisy chained together, the wires were not colour coded, and the pedestal looked like a rat’s nest of wires.  Likewise, the wiring of the Master Caution System (MCS) required upgrading as several of the original wires showed signs of fraying.  

A word of thanks goes to a friend (you know who you are...) who helped wade through the labyrinth of wires!

This post shares several links to other pages in the website.

Wiring Redesign (pedestal and panels)

The set-out of the inside of the center pedestal was redesigned from the ground up, and several of the pedestal panels re-wired to ensure conformity to the new design standard, which was neater and more logical than its predecessor.  Additionally, the MCS was rewired using colour-coded wire and the wires labeled accordingly.

New Design (panels must be stand-alone)

The new design called for each panel (module) that was installed into the pedestal to be stand-alone.  Stand-alone means that if removal of a panel was necessary, it would be a simple process of unscrewing the DZUS fasteners, lifting the panel out and disconnecting a D-Sub plug and/or 5 volt backlighting wire.   Doing this with panels that were daisy chained together was impossible.

LEFT:  B737-800 EVAC panel, although not a panel that resides in the pedestal, it demonstrates the 'stand-alone' panel philosophy.  One D-Sub plug with labelled and colour-coded wire.  The mate of the D-sub resides inside the pedestal with the wires connected to the appropriate busbar (click to enlarge).

The following panels have been re-wired:

(i)      EVAC panel;
(ii)     Phone panel;
(iii)    ACP units (2);
(iv)    On/off lighting/flood panel; and,
v)      Radar panel.

All the panels have been retrofitted with colour-coded and labeled D-Sub connections.  Removing a panel is a simple as unfastening a DZUS connector, disconnecting a D-Sub connector, and unscrewing the 5 volt backlighting wire from the 5 volt terminal block (if ued).  If a USB cable is needed for the panel, then this must also be disconnected.

A word concerning the ACP units, which were converted some time ago with an interface card located on a separate board outside of the unit.  As part of the rebuild, the two ACP units were completely re-wired to include the interface card within the unit.  Similar to the fire suppression panel, the ACP units are now stand-alone, and only have one USB cable which is used to connect to the computer.  The First Officer side ACP is daisy chained to the Captain-side unit.

Center Pedestal Flat Board

A flat board 1 cm in thickness and constructed from wood was cut to the same dimensions of the pedestal base.  The board was then attached to the inside bottom of the pedestal by screws.  The wood floor has been installed only to the rear two thirds of the pedestal, leaving the forward third open to allow easy access to the platform floor and area beneath the floor structure..

Attached to the flat board are the following items:

(i)       FDS 5 Volt IBL-DIST panel power card (backlighting for FDS panels);
(ii)      28 Volt busbar;
(iii)     5 Volt busbar (backlighting);
(iv)     12 Volt relay (controls backlighting on/off tp panel knob);
(v)      Terminal block (lights test only);
(vi)     Light Test busbar;
(vii)    OEM aircraft relay; and a,
(viii)    Powered USB hub (NAV, M-COM, ACP & Fire Suppression Panel connection).

The 5, 12 and 28 volt busbars (mounted on the flat board) receive power continuously from the power supplies, mounted in the Power Supply Rack (PSR) via the System Interface Module (SIM). Each panel then connects directly to the respective busbar depending upon its voltage requirement.  

In general, 5 volts is used for panel backlighting while 12 and 28 volts is used to power the fire suppression panel, EVAC, throttle unit, and phone panel.

The flat board has a fair amount of real-estate available; as such, expandability is not an issue if additional items need to be mounted on the board.

Lighting Panel Knob (backlighting on/off)

All the panels in the center pedestal require 5 volt power to illuminate the backlighting.  The general purpose knob located on the pedestal OEM lights panel is used to turn the backlighting on and off.  

LEFT:  Lights Test busbar.  Similar in design to the 5 volt busbar, its use centralizes all wires and reduces  the number of connections to a power supply.  Despite the pedestal rewire, there is still a lot of loose wire that cannot be 'cleaned up'.  The grey coloured object is the flat board  (click to enlarge).

Instead of connecting each panel’s wire to the on/off lights panel knob – a process that would consume additional wire and look untidy, each wire has been connected to a 10 terminal 5 volt busbar.  The busbar in turn is connected to a 12 volt relay which is connected directly with the on/off knob.

When panel lights knob is turned from off to on, the relay closes the circuit and the busbar is energised; any panel connected to the busbar will automatically receive power.

The busbar and relay are mounted to the flat board.

This system has the advantage that it minimizes the number of wires that are connected to the lights panel knob.  It also enables one single high capacity wire to connect from the relay to the knob rather than several smaller gauge wires.  This minimises the heat produced from using several thinner wires.  It is also easier to solder one wire to the rear of the panel knob than it is to solder several wires.

Lights Test and DIM Functionality

The center pedestal also accommodates the necessary components (Lights Test busbar) to be able to engage the Lights Test and DIM functionality.  These functions are triggered by the Lights Test Toggle located on the Main Instrument Panel (MIP).  

Interface Cards

In the previous throttle quadrant, a number of interface cards were mounted within the center pedestal. 

LEFT:  All wires have been corrected colour coded to various outputs and wire ends use ferrules to connect to the card (click to enlarge).

To ensure conformity, all the interface cards have been removed from the pedestal and are now mounted within one of the interface modules located forward of the simulator. 

Furthermore, all the wiring is colour-coded and the wire ends that connect into the I/O cards use ferrules.

The use of ferrules improves the longevity of the wiring, makes wire removal easier, and looks neater.

Wiring and Lumens

Needless to say, the alterations have necessitated rewiring on a major scale.  Approximately 80% of the internal wiring has had to be replaced and/or re-routed to a position that is more conducive to the new design.

LEFT:  The First Officer-side MCS completely rewired.  The MCS has quite a bit of wiring associated with it, and making the wire neat and tidy, in addition to being rellatively accessible, was a challenge (click to enlarge).

The majority of the wiring required by the throttle unit now resides in a lumen which navigates from the various interface modules (located forword of the simulator) to the Throttle Communication Module (TCM).  

From the TCM the lumen routes through the throttle firewall, along the Captain-side of the throttle unit before making its way to the flat board in the center pedestal.  

The exception to the above is the cabling required for a powered USB hub located within the center pedestal, thw wires required for the Lights Test (from the Lights Test Toggle located in the MIP), and the various power wires navigating to the pedestal from the Power Supply Rack.  These wires have been bundled into a separate lumen, which resides beneath the floor structure.

Wire Management

Building a simulator using OEM parts, requires an inordinate amount of multi-voltage wiring of various gauges, and it can be challenge to maintain the wire in a neat and tidy manner. 

LEFT:  Identifying the voltage of wires is an important aspect of any simulation build (click to enlarge).

Running the wire through conduits and lumens does help, but in the end, due to the amount of wire, the number of connections, and the very limited space that is available, the wire is going to appear a little messy.  Probably more important, is that the wire conforms to an established design standard – meaning it is colour-coded and labelled accordingly.

A dilemma often facing builders is whether to use electrical tape to secure or bind wires.  Personally, I have a strong dislike for electrical tape - whilst it does have its short-term usages, it becomes sticky very easily, and becomes difficult to remove if left on wires for a considerable time .

My preferred method is to use simple cable ties, snake skin casing, or to protect the wires near terminals of OEM parts. to use electrical shrink tubing (which can be purchased in different colours for easy identification of wires and terminals).

Final Product

The design and rewiring of many parts in the simulator has been time consuming.  But, the result has been:
(i)     That all the wires are now colour-coded and labelled for easy identification;
(ii)     The wiring follows a defined system in which common-themed items have been centralised.  
(iii)    Panels that were daisy chained have been rewired with separate D-Sub plugs so they are now stand-alone;
(iv)    The  frayed wires from the MCS have been replaced with new wires; and,
(v)    The wires in general are neater and more manageable (the rat's nest is cleaner...).