Journal Archive (Newest First)

AVIONICS AND CENTER PEDESTAL

The word avionics is the combination of two words: aviation and electronics and refers to the electronic systems on board the aircraft.

The type and style of avionics found in a Boeing 737 aircraft varies enormously.  Often there is a combination of panels from different suppliers (GME, Gables, Honeywell, etc).

Avionics B737-800 NG

The set-out of the various avionics within the NG center pedestal is not uniform.  While some airframes will have standardized panels, others are at the discretion of the airline.  Likewise, the brand and style of avionics panel may differ from airframe to airframe, as does the colour of the panel.

Spaces that are not filled are blanked off by what is called a blank.  A blanking plate is piece of metal that fits the space and is secured to the pedestal rail by two or four DZUS fasteners.

The following panels are standard across all airlines and are compulsory as per aviation regulations in the B737-800:
(i)         Nav 1/2 Radio;
(ii)        Nav 1/2 Radio;
(iii)       ADF 1/2 Radio;
(iv)       ASF 1/2 Radio;
(v)        VHF Communication Radio 1;
(vi)       VHF Communication Radio 2;
(vii)      Transponder Panel;
(viii)     Stab Trim and Cabin Door Panel;
(ix)      Flood and Lighting Panel;
(x)       Audio Control Panel (also called Audio Switch Panel/ASP);
(xi)      Weather Radar Panel;
(xii)      Rudder Trim Module;
(xiii)     Cargo Fire Panel, and;
(xiv)     Fire Suppression Panel.

The direction and length of this post does not subscribe to a discussion on various customized panels; however, some custom panels are the phone panel, multi communications panel (VHF 1,2,3 and HF), Multi-Mode NAV Control Panel, ACARS and SelCal (selective calling) Panel.

Avionics Selection

If using converted OEM parts then there is no recourse for complaint; however, if using reproduction avionics then your selection must be on par with your expectation; otherwise, your enjoyment level will plummet. 

More importantly, any reproduction panel/instrument purchased must be of the highest quality to ensure trouble free operation.  

Avionics Used

The following avionics & gauges are used in the MIP and center pedestal.  Several of the OEM parts are from Boeing 500 series airframes and are identical to those panels and gauges used in the B737-800 NG.

Hyperlinked entries navigate to other pages on the website in which these items have been discussed in more detail.  Using the search function may also find additional information. 

It is very easy to become carried away with avionics and spend a small fortune on standby instruments and avionics panels.  Therefore, a step/phase approach is a good idea when determining what you need. 

Avionics Modules - Compliance, Back Lighting and Colour

The main reason for trying to maintain compliance with avionics is that manufacturers of reproduction panels, produce panels differently from each other.  Size, ease of installation, material, connection set up, panel colour, and the type and colour of the back lighting can vary between manufacturers. 

Flight Deck Solutions (FDS), CP Flight, SISMO, Open Cockpits and several other companies produce avionics modules that are identical in size to their real life Boeing counterparts, however, each company uses a different set-up to allow connection of the module to the computer.  Furthermore, each companies back lighting is subtly different. 

CP Flight use LEDS for back lighting whilst FDS use real aircraft bulbs (FDS call their back lighting Integrated Back Lighting).  OEM parts mostly use 5 and 28 volt bulbs.  Personally, I prefer the back lighting illuminated by incandencent bulbs as this is identical to that in a real Boeing aircraft; however, this comes at a cost - Back lighting using 28 Volt bulbs runs very hot and can draw a considerable amount of power.  Mixing bulbs and LEDS can, because of their different colour temperatures, create a light imbalance which often can appear disconcerting.  This said, often it is not possible to only have one brand of avionics, so a compromise must be made.

It must be remembered, that real aircraft rarely have the same lighting or avionics panels installed.  Often there is a avionics mismatch as newer items are retrofitted to replace older style items.  Therefore, a lighting imbalance is not unrealistic. 

Similarly, it is not uncommon to observe different shades of grey used on various panels.  Aircraft engineers are more concerned with getting the aircraft back into the air when replacing a panel; they do not care that that the shade of grey the panel is painted is a slightly different hue to that off its mate.

The reproduction panels being used in the simulator are manufactured by Flight Deck Solutions and CP Flight, all other modules are OEM.  In time, it is hoped to replace the reproduction parts with OEM parts.

Glareshield - MCP and EFIS Units 

The Mode Control Panel (MCP) and Electronic Flight Instrument System (EFIS)  are the Pro series supplied by CP Flight in Italy. CP Flight produce some excellent reproduction parts for the B737 and, more importantly, the company stands by the products they manufacture and sell.  Their after sales and support service are excellent.

In the future, the MCP and EFIS may be replaced with an OEM unit, but this will not be in the immediate future.

Center Pedestal

The center pedestal, or aft electronics bay (P8), is attached to the throttle quadrant.  The primary purpose of the pedestal is a platform to hold a number of several avionics panels – some standard, and others customized to an airline’s preference at the time of order.

LEFT: Next Generation B737 Center Pedestal (click to enlarge).

Design Evolution - 100 Series to Next Generation (NG)

The pedestal, similar to the throttle quadrant, has evolved through time and today looks starkly different to those pedestals used in early 737 airframes.  Initially the design of the pedestal changed minimally between the early 737 airframes; however, the advances in technology, especially in relation to electronics were the catalyst to the design being altered.

It must be noted that the specifics noted bellow are general.  As with many products, there are variants in design that may only have been released for a short period of time before being phased out of service or discarded un future intermediate designs. The below synopsis identifies the major differences between pedestals.  

The 100 and 200 series throttle units use a two-bay pedestal made from aluminum.  This pedestal is specific to the Boeing B737-100/200 series air frame, in that the rudder trim module, which was an exceptionally bulky unit, formed part of the aft end of the pedestal.  The rudder trim in both these airframes were a hand-me-down from the B707 days when there was more hand flying and asymmetric thrust prior to the introduction of the autothrottle.

The 300 series continued, more or less, with the same two-bay design, but without the large rudder trim module.  Interestingly, both these designs incorporated a folding-style cup holder (for drinks) on each side of the pedestal. 

LEFT:  300 series folding cup holders (click to enlarge).

A telephone and microphone system was accommodated on the rear of the pedestal; a production combination that continued through to the 400 and in part, 500 series airframes.

The 400 series saw two pedestal designs released – early and mid production 400 series air frames used the same pedestal as the earlier 300 series; however, some late production 400s used the three bay pedestal.  In these designs, the folding cup holders were replaced with a solid non-folding cup holder which formed part of the front quarter of the pedestal.  The pedestals were still, constructed from aluminum.  

The 500 series utilized a three-bay pedestal which was made from a composite fiber-based material (similar to fiberglass) with the upper edge of the pedestal constructed from aluminum.  The telephone and microphone system was repositioned on some 500s to the upper side of the pedestal.

The pedestal design in the NG differs slightly from the 500 series in that the telephone and microphone have been discarded in lei of more modern communications equipment located elsewhere. 

Furthermore, the colour of the pedestal frame has been altered from light Boeing grey to stark Boeing white; the material used t to construct the pedestal is still a fiber-based product.  All pedestals used in the NG are three-bay; a discussion which will be continued shortly.
Although the width, material used, and colour of the pedestal has changed through time, the method used to secure the avionics to the pedestal has remained unchanged. 

DZUS Fasterners and Rails

All panels are secured to the pedestal by DZUS fasteners.  These fasteners allow a panel to be securely attached to the DZUS rail by a 90 degree quarter turn by a flat-blade screwdriver. 

LEFT: DZUS fasterners and rail (click to enlarge).

The fastener, designed in the 1930’s by William Dzus.  The fasteners are notable in that they are of an ‘over-centre’ design, requiring positive sustained torque to unfasten. Thus, any minor disturbance to the fastener will tend to correct itself rather than proceed to further loosening as it would in threaded fasteners.

The fasteners are attached to a rail, which runs the length if each bay within the pedestal.  A three-bay pedestal will have six rails, while a two-bay will have four rails.

Fundamental Changes

The fundamental change between the earlier and later pedestals was the width of the bay. Earlier designs incorporated two bays while later designs used three bays. 

The reason for the increased width of the pedestal was to facilitate the accommodation of the various avionics panels that modernization had developed, and to allow redundancy of several panels.   Simply put, there was not enough room in the older styled two-bay pedestal to fit the avionics to operate a modern jetliner.

The change in the width of the pedestal had huge ramifications concerning the available space in the flight deck.  Two-bay pedestals allowed pilots to climb easily in and out of the flight deck whilst the three-bay pedestal called for a redesign to be made to the seating arrangement. 

The earlier style Weber seats, which used claw feet as attachment points were removed, and replaced with Ipeco seat.  The Ipeco did not have claw feet but used a rail system which enabled the seat to be maneuvered rearward and to the left (Captain) or to the right (First officer).  It should be noted that some Weber seats were customized to fit rail systems; however, this was not the norm.

Acronyms

OEM - Original Equipment Manufacture (aka real aircraft part).