B737 Center Pedestal Completed and Installed - Flight Testing Begins — Flaps 2 Approach

oem 737-500 center pedestal and custom panels. The center pedestal from the 500 series is very similar to that of the next generation

After spending the best part of two weeks wiring the various panels into the center pedestal I am now pleased with the result.

The center pedestal is from a Boeing 737-500 and is made from fibreglass. The earlier series two-bay pedestals were made from aluminium. The three bay pedestal allows much more room inside the pedestal to mount interface cards and house the wiring for the various panels (modules).

However, as with every positive there often is a drawback. In this case there are two drawbacks. The first is a few spare holes must be covered with OEM blanking plates, and the second is the three bay pedestal is considerably wider than a two bay pedestal. Whilst climbing into the flight deck is easy at the moment, once a shell is fitted, J-Rails will need to be fitted to the seats to allow easy access.

Space

Taking advantage of the extra internal space of a three bay, I have constructed a small shelf that fits inside the lower section. The shelf is nothing fancy - a piece of wood that fits securely between the two sides of the pedestal. Attached to this shelf are bus bars, a Leo Bodnar interface card and a FDS interface card. A Belkin powered hub also sits on the shelf. The power supply for the hub resides beneath the platform to the rear ( for easy access).

The bus bars provide power for the various OEM panels and backlighting, while the Leo Bodnar card provides the interface functionality for the two ACP units. The FDS card is required for operation of the three FDS navigation and communication radios I am currently using.

My aim was to minimise cabling from the pedestal forward to the throttle unit. The reason for this is the throttle is motorized and moving parts and USB cables do not work well together. I have two cables that go forward of the pedestal to the computer; one USB cable from the powered Belkin hub and the other the cable required to connect the CP Flight panels. Both cables have been carefully routed along the inner side of the throttle quadrant so as to not snag on moving internal parts.

Pedestal Colour

The original pedestal was painted Boeing grey which is the correct colour for a B737-500. The unit was repainted Boeing white to bring it into line with the colour of the B737-800 NG pedestal.

oem 737-500 center pedestal illuminated by 5 volt incandescent bulbs

Backlighting

The backlighting for the throttle quadrant and center pedestal is turned on or off by the panel knob located on the center pedestal. Power is from a dedicated S-150 5 Volt power supply rated to 30 amps.

“On the Seventh day, GOD created backlighting and the backlighting was said to be good”.

The light plates are mostly aircraft bulbs; however, a few of the panels, such as the phone and EVAC panel, are LEDS and operate on 28 Volts rather than the standard 5 Volts.

Size Does Matter...

It's important when you install the wiring for backlighting that you use the correct gauge (thickness) wire. Failure to do this will result in a voltage drop (leakage), the wire becoming warm to touch, and the bulbs not glowing at their full intensity. Further, if you use a very long wire from the power supply you will also notice voltage drop; a larger than normal wire (thickness) will solve this problem. There is no need to go overboard and for average distances (+-5 meters) standard automotive or a tad thicker wiring is more than suitable to cater to the amp draw from incandescent bulbs.

To determine the amperage draw, you will need to determine how many amps the bulbs are using. This can be problematic if you're unsure of exactly how many light plates you have. There are several online calculators that can be googled to help you figure out the amperage draw. Google "calculation to determine wire thickness for amps".

At the moment, I am not using a dimmer to control the backlighting, although a dimmer maybe installed at a later date.

Minor Problem - Earth Issue

A small problem which took considerable time to solve was an earth issue. The problem manifested by arcing occurring and the backlighting dimming. I attempted to solve the problem by adding an earth wire from the pedestal to the aluminium flooring; however, the issue persisted. The issue eventually was tracked down to an OEM radar panel which was "earthing" out on the aluminum DZUS rails via the DZUS fasteners. To solve the problem, I sealed the two metal surfaces with tape.

Panels

The panels I am currently using are a mixture of Flight Deck Solutions (FDS), CP Flight, 500 and Next Generation:

NAV 1/2 (FDS)
M-COM (FDS)
ADF 1/2 (CP Flight) - replaced with FDS
Light Panel (OEM)
Radar Panel (OEM)
EVAC Panel (OEM)
Phone Panel (OEM)
Rudder Trim Panel (CP Flight) - replacd with OEM
ATC Transducer Radio (OEM)
ACP Panel x 2 (OEM)
Fire Suppression Panel (OEM)

In time a ACARS printer will be added and some of the non NG style panels (namely the ACP panels) will be replaced with OEM NG style ACP panels. The OEM panels installed are fully operational and have been converted to be used with Flight Simulator and ProSim737. I will discuss the conversion of the panels, in particular the Fire Suppression Panel, in separate journal posts.

The more observant readers will note that I am missing a few of the "obvious" panels, namely the cargo fire door panel and stab trim panel. Whilst reproduction units are readily available, I'm loathe to purchase them preferring to wait; eventually I'll source OEM panels. Rome was not built in a day.

Panel Types

If you inspect any number of photographs, it will become apparent that not all aircraft have exactly the same type or number of panels installed to the pedestal. Obviously, there are the minimum requirements as established by the relevant safety board; however, after this has been satisfied it's at the discretion of the airline to what they order and install (and are willing to pay for...). It's not uncommon to find pedestals with new and old style panels, incandescent and LED backlighting, colour differences and panels located in different positions.

oem 737-500 center pedestal telephone. although not next generation it completes the pedestal

Telephone Assembly

Purists will note that the telephone is not an NG style telephone and microphone. I have keep the original B737-500 series telephone and microphone as the pedestal looks a little bare without them attached.

If at some stage I find a NG communications assembly I'll switch them, but for the time being it will stay as it is.

Flight Testing - Replication

The throttle quadrant and center pedestal are more or less finished. The next few weeks will be spent testing the unit, it's functionality, and how well it meshes with ProSim737 in various scenarios. This process always takes an inordinate amount of time as there are many scenarios to examine, test and then replicate.

Replication is very important as, oddly, sometimes a function will work most times; however, will not work in certain circumstances. It's important to find these gremlins and fix them before moving onto the next level.

KIS - Keep It Simple

Although everything is relatively simple in design (OEM part connects to interface card then to ProSim737 software), once you begin to layer functions that are dependent on other functions working correctly, complexity can develop. It's important to note that the simulator is using over a dozen interface and relay cards, most mounted within the Interface Master Module (IMM) and wired to an assortment of OEM parts configured to operate with ProSim737's avionics suite.