Using OEM Panels in the MIP

OEM Captain-side DU panel. Note the thick engraving and specialist DZUS fasteners

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.

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.

Close up detail of OEM lightplate and general purpose knobs

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.

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.

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

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, or 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.

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.

DZUS fastener that secures DU panel to the MIP framework

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.

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).

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

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.

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

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.

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 becomminginceasingly common to use along with specialist interface cards, and these will be discussed in separate articles.

Rear of DU panel showing korry connections and AFDS bracket

The Future

The FDSMIP 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.

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 pin-outs 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.

Acronyms