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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).


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

Journal Archive (Newest First)

Entries in Genuine Aircraft Parts (18)


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

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

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

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

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

The chart lights are mounted near each the eyebrow windows.

Two Styles (Classic and NG)

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

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

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

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

Ingenious Design

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

LEFT:  Chart light showing reflector dish on inner side of end cap.  This style is the older light type used in the 737 classic airframes (Click image for larger view).

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

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


Original Equipment Manufacturer (OEM)

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

LEFT:  The NG style chart light.  A blade aperture controls the amount of light that is reflected onto the thick lens glass (click image to enlarge).

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


OEM Boeing 737 Stick Shaker - Interfacing and Operation

The stick shaker is standard on all Boeing series aircraft; the NG having two units and the earlier classic series having one unit.  The stick shaker is mounted directly to the control column and is designed to vibrate if air speed degrades to stall speed.  The unit is manufactured by a company in New York and is operated by 28 Volts (27.5 Volts to be exact).  

Some of this post has been recycled from an earlier post which did not have enough detail.


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

To allow Flight Simulator to connect to the stick shaker, a relay card is required such as a Phidget 0/4/4 relay card.  A USB cable then connects from the card to the computer.  The stick shaker will vibrate when pre-established attributes concerning low air speed are met.  This is defined by the flight avionics software.

LEFT:  OEM B737 stick shaker installed to Captain-side column.  The lower section of device is what vibrates.

Interfacing and Wiring

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

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

LEFT:  Phidget 0/0/4 relay card showing the main positive wire (red wire) cut with each end inserted into the correct terminals of the relay card (click to enlarge).

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

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


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

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

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

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

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

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

Incorrect Wiring

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

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

Although the stick shaker is not essential, it’s often the smaller things and attention to detail which help bring the simulator to the next level.  I am using OEM control columns; therefore, adding the stick shaker seemed to be an obvious requirement.


OEM - Original Equipment Manufacture (real aviation parts)

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


Genuine B737 Forward & Aft Overhead Panels Purchased

For some time I’ve been debating whether to use a reproduction or genuine forward and aft overhead panel.  I have been favouring a genuine panel as this is in line with using genuine parts in the simulator, however, the overhead is a complicated piece of kit and ensuring complete functionality would be  a challenge.

RIGHT:  Forward Overhead Panel.  The centre panels will be replaced to conform to a 737 NG.  Panel was removed from a United Airlines 737-300 aircraft.

Certainly, using an overhead panel made by Flight Deck Solutions (FDS) or Fly Engravity is an easier option, however, their overheads use flight illusion gauges and I don’t want to go down this route.  After seeing and using genuine gauges in the MIP I can see a huge difference in quality and aesthetics between a genuine gauge and those produced by flight illusion.  

Genuine B737 Overhead Panel Purchased

My decision was made for me when I was told a forward and aft overhead had become available from a recent 737 pull down.  Rather than remain indecisive, I thought I’d jump in “boots and all” and purchase it.  The two overhead panels have come from B737-300 and include the frames, DZUS rails, center panels, engine starter switches, landing gear toggles and various other knobs and toggles.

I’m impressed at the condition of the panels; usually when panels are removed from an aircraft in a tear down yard there is little care given and the frames become scratched, dented or damaged in some way.  The frames I have purchased appear to be in relatively good condition.  

Cole Switches

I was very lucky that the two engine starter switches (Cole switches) were included.  These switches are made to exacting requirements and use a solenoid mechanism.  Purchasing Cole switches individually is quite expensive, so I'm pleased they were not striped from the overhead.

LEFT:  Difficult to find operating Cole switches are used on all Boeing airframes from the 727 through to the NG and I believe NGX (click to enlarge).

Panels and Back Lighting

When I began to construct the simulator in mid 2011, I was adamant that back lighting should match that of the MIP, throttle quadrant and center pedestal.  My opinion has altered since then and now I am happy to have a mix of IBL bulb and LED lighting (within reason).  I believe it was around 2006 that Boeing began to replace bulb-generated back lighting with LEDS.  Certainly, the latest made Boeing now uses LEDS for IBL and older airframes, with replacement parts will present with a mix of lighting types. 

The use of bulbs in the overhead uses a lot of power and generates considerable heat; using LEDS minimises power consumption and produces less heat.  If the LEDS are installed correctly, their resultant light is very similar to that of bulbs and the illuminance observed in the real aircraft.

Ultimately the back lighting will be dependent on whether I decide to use older style genuine Boeing panels or reproduction panels.

Realism & Authenticity - How Far Do You Go

Some flight deck builders go to extremes to ensure their flight decks replicate exactly what is seen in the real aircraft and while this is admirable, this is not the route I am 'religiously' going to travel.  There has to be compromise between replicating something exactly and having a functional flight simulator.

The end product will  be a combination of genuine (OEM) and reproduction parts - mostly OEM.

Furthermore, serious thought must also be given to how the overhead is going to be installed to the simulator; whether it be to a shell, such as produced by FDS or to a custom-made roll cage assembly.

I'll keep the Blog updated as parts are found and the overhead is developed.

To see additional images of the "naked" overhead, navigate to the image gallery.

  • I must apologise for the poor resolution of these images; they were supplied by the vendor. Currently the overhead is still located in the US.  In time better quality images will be uploaded.

B737-800 Cabin Phone System Panel - Center Pedestal

I recently acquired an avionics panel that is quite unique.  The panel was acquired from a company that was responsible for altering the on-board communication system for 50 Boeing 737-800 jetliners; the aircraft were being refitted with global communication equipment.  The upside for me was that the panels were being decommissioned and were not required by the supplier.

LEFT: Panel has three push buttons with backlighting and legends, and one toggle button (click image for larger view).

Late model NG panels are uncommon to find; therefore, it is interesting to observe the differences between the older style classic panels regularly seen on e-bay, and a newer style panel. 

The first thing that comes to mind, other than condition, is the lack of a rear box assembly on this panel.  Instead of an aluminum box, the wiring is protected by a stainless bracket assembly.  The wiring looms are also much more refined and neater looking, while the backlighting, rather than using 5 Volt bulbs uses LED technology.

LED Technology

Most people are familiar with the 5 volt incandescent bulbs used to illuminate the light panels in Boeing aircraft - the bulbs produce a soft yellow-orange hue.  The colour temperature is in stark contrast to the white hue produced by LED technology. 

I beleive that airframes post 2006 utilise LED technology.  Notwithstanding this, until older airframes are phased out, panel lighting will be a mixture of incandescent and LED lighting, or a combination thereof. 

Matching Colour Hue

Attempting to  match the backlighting colour hue, especially in the center pedestal and overhead panels has always been a challenge for flight deck builders, especially when using an assortment of older style OEM panels and panels made by differing companies (FDS, CP Flight, Open Cockpits, SimWorld, etc).  

What many virtual pilots forget is that the only purpose for an airlines existence is to generate income and a profit for the company. Pilots on the other hand are more concerned with flying the aircraft. 

LEFT:  Wiring is very neat and the panel does not utilise the more commonly found aluminum box structure (click image for larger view).

There is very little thought as to whether a panel's backlighting is the same colour hue throughout all the panels.  If and when a panel needs to be replaced, a technician’s only concern is getting a workable and certified instrument fitted into the aircraft as quickly as possible. 

What this means for purists is that it is not unrealistic have a combination of backlit panels in the center pedestal, overhead, or MIP.

Cabin Phone System Panel - What Works

Although there is no obvious use for this panel in the simulator, it is a good-looking panel that improves the overall aesthetics - it fills a 'gap' in the three-bay center pedestal.  The buttons do function and when depressed change colour and provide different cautions and call outs.  Lifting the red cover and pushing the toggle to test causes the third button to illuminate 'smoke' in orange.

Although the panel has not been connected to an interface card, it is an easy process to connect a POKEYS or Leo Bodnar interface card to the wiring lumen, allowing connection with Flight Simulator.


Replacement Genuine 737 Throttle & Center Pedestal - Full Conversion to NG Style

The last few months have seen quite a bit of activity regarding the throttle quadrant and center pedestal, which has culminated in me selling my former 300 series TQ and pedestal and replacing it with an another unit from a late series 500 airframe.

Brief Recap

In an earlier post late in 2012, I decided to convert the 737-300 throttle to full automation.  A dilemma I faced was whether to keep the throttle unit as a 300 series throttle with the attached two-bay pedestal, or do a full conversion to make it similar to the Next Generation (NG) style. 

After careful consideration, a decision was made to convert the throttle quadrant to a full NG style, bringing the throttle units and center pedestal in line with a 737 NG airframe for which the MIP is designed.

Stab Trim Switches

One of the biggest differences, apart from thrust lever handles, between early model throttle units and the NG units is the stab trim cut out switches.  On the earlier 300 series units, the switches are paddle / lever style switches while the NG uses toggles and T-Locks.  T-Locks are a safety feature and sit beneath the toggle switches and are spring loaded; the pilot must push down the T-Lock to activate the toggle.  

LEFT:  737-300 TQ with old style paddle-style stab trim levers.

To convert the trim switches requires cutting out the old switches and fitting new reproduction NG style switches.  This is a major task requiring precision work of a surgical nature.  Although reproduction switches can be made, the reproduction T-Locks don't operate as the real T-Locks should.  I did search for some genuine T-Locks and toggles, however, my search was fruitless as these parts appear to be reused by airlines.

Replacement 500 Series Throttle Quadrant & Three-Bay Center Pedestal

A friend of mine informed me that a late model 737-500 throttle quadrant was for sale.  This unit was in better shape than my existing throttle, included the genuine 'NG style' stab trim switches complete with T-Locks, and also had a three-bay center pedestal.  It appears provenance was shining on me as the new throttle appeared for sale a day before the stab trim switches were about to be removed (with a metal cutter...)

The throttle and center pedestal were purchased (you only live once!) and the 300 series unit sold to an enthusiast in Sweden.

NG Conversion

To bring an earlier style throttle and center pedestal in-line with a NG airframe requires, at a minimum:

  • Attachment of a NG style throttle lever shroud to existing aluminium levers;
  • Removal of TO-GA buttons and relocation to bring design in-line with a NG (the buttons are identical, but the housing is different);
  • Possible replacement of the stab trim switches;
  • Painting of throttle housing and center pedestal from Boeing grey to Boeing white; and,
  • Painting of all throttle knobs from Boeing grey to Boeing white.

The biggest hurdle is usually replacing the trim stab switches, however, as these are already present on the new throttle, and are the NG style, considerable time and expense was saved in not having to replace them.

Main Differences - NG & Classic

The Boeing airframe that most people associate with today begins with the 737-200 and ends with the 737-800 NG.  In between we have the classics which refer to the 737-300, 400 & 500 series airframes and the NG, which stands for Next Generation and incorporates the 737-600, 700, 800 & 900 series airframes.

The main differences between a classics and NG throttle quadrant are:

  • The stab trim switches are slightly different; the classics having two flat levers while the NG has toggle-style buttons with T-locks;
  • The throttle thrust lever handles; the classics are bare aluminium and the NG is white aluminium that is ergonomically-shaped.  The TO/GA buttons are also positioned in a different place on the NG.  The knobs (handles) on the levers are also coloured white rather than off-grey;
  • The method that the throttle thrust levers move during automation.  The classics move both thrust levers together when auto throttle is engaged.  The NG moves each lever individually in what often is termed the throttle dance (this is due to the computerised fuel saving measures incorporated in the NG);
  • The spacing (increments) between each flap lever position is identical in the NG, but is different in the earlier series throttles;
  • The center pedestal in the classics is either a two-bay pedestal (early 300 series and before), but more likely a three-bay pedestal.  The NG always has a three-bay pedestal.  Base materials for the center pedestal are also different - aluminium verses a plastic composite material;
  • The speedbrake knob is very slightly more elongated on the NG unit; and,
  • The telephone, circuit breakers and mike assembly differ in type and location

NG Skirt - Thrust Levers

Boeing when they designed the NG style throttle didn’t design everything from new; they added to existing technology.  All NG throttles utilise thrust levers which are identical to those of earlier units.  

Boeing designed a shroud or skirt that attaches over the existing thrust levers encapsulating the older thrust levers and sandwiching them between two NG style pieces.  The assembly is made from aluminium and is painted white.

The TO-GA buttons are located in a different position on the Next Generation units, although the buttons used are identical.

To alter the position of the TO-GA buttons you must detach  the small aluminium box from the 300 series thrust levers, remove the TO/GA buttons, and then re-solder the buttons in the appropriate location on the new unit.

I did not make the NG skirt for the thrust levers, but rather had fabricated, from design specifications, a reproduction skirt.  The skirt is produced from aluminium and replicates the dimensions of the Boeing part.

Time-line, Functionality and Conversion

The TQ is initially being converted in the United States.  The advanced work will be done by a good friend in California, and then by myself after delivery.

The replacement unit will feature several imrovements which will allow: full motorized functionality, full speed brake capability, accurate trim tab movement, alternate trim wheel spin speeds, correct park brake release, trim wheel braking and several other features. 

I want the functionality of the TQ to be as close as possible to that found in the real aircraft; therefore, the methods used to ensure this functionality will be slightly different from the norm.

When the TQ is fully functional and tested, I'll publish a post providing further information and detailed photographs of the various functions.

It is hoped everything will be completed, and the TQ and pedestal installed by late May 2013.  The next month or so will be quite exciting.

Two-bay Pedestal Will Be Missed

I know I will miss the narrower two-bay center pedestal.  A major advantage that will be lost is the ease in climbing into and out of the flight deck; the two-bay provided more room between the pedestal and the seats.  At some stage, I probably will need to install J-Rails because the seats I'm using are fixed-claw feet Weber pilot seats; J-Rails will be needed to allow lateral seat movement.

BELOW:  Montage of several images showing main visual differences between 737-300 classic series throttles and the 737 NG style throttle units. The 300 series TQ is my old throttle unit but, the NG TQ belongs to a mate of mine.