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The Great Aircraft Parts Debate - Part one - Switch Panels



No technical conference where the design and/or maintenance of Flight Simulation Training Devices (FSTD) is discussed would be complete without a debate on the virtues of, or limitations of, simulated parts. Strong and emotive views are often expressed. This week we take a first look at the topic and try to put some of the arguments in perspective.


What parts are we talking about?

In general there are two main categories discussed: firstly what you can see and touch in the flight deck representation and secondly there are the rack mounted avionics, what used to be called black boxes.


Within the flight deck there are many parts; Instruments, displays, controls, fixtures and fittings (such as lining panels). We were recently sent some photos of an inservice Full Flight Simulator (FFS) where those were looking decidedly worn with a request to help. So this week we thought we would look at switch panels.


So why is there a debate?

Aircraft parts are expensive, very expensive. This is largely because they have to go through a long and complicated certification process but also, as with buying spares for your car, the aircraft manufacturers charge a premium for spare parts. With the unrelenting pressure to reduce the price tag of the simulators the Training Device Manufacturers (TDMs) are naturally attracted by any opportunity to save costs by using replicated parts. These give them the opportunity to source from commercial manufacturers (or make themselves) to their own designs at a lower cost.


Incidentally we have often heard it said that a reason to use simulated parts is due to “long lead times” for aircraft parts. However in our experience we have found that both the aircraft manufacturers and individual parts suppliers are extremely helpful in assisting the TDMs to manage these, particularly when the TDMs share production forecasts. Lead Times can be managed.


So what about Switch Panels

Those are panels that have a mixture of switches (pushbutton, rotary or toggle) and indicator lights grouped by system with a backlit panel, lightplate.


Traditionally most of the TDMs were taking a similar approach. That being to have the switches and indicators the crew touch and the back lit panels as aircraft (what you can see and touch). Whilst the back of the panel is simulator unique with either a serial interface card, CanBus or ethernet predominantly, on newer FSTDs or wired back to linkage boards on older FSTDs. This is for good reasons, in general the complete aircraft parts, leaving aside their cost, are difficult to integrate into an FSTD. Many have unique interfaces and some have inbuilt logic.


But to save money some TDMs have had items such as the back lit panels made locally to their own designs, some have also sourced cheaper, non-aircraft qualified, switches and indicators.


A word about Aircraft OEM kits

For as long as we can remember the established aircraft Original Equipment Manufacturers (OEMs) have done a great job defining and provisioning kits of parts for the early build FSTDS when new aircraft are being developed, these FSTDS being predominantly FFS. Without this it would be almost impossible for the crews to be trained in time for introduction into service. However, whilst universally welcomed on new aircraft programmes, they are not welcomed by everyone on sustaining types. The problem is that the kits tend to be an all or nothing deal which means that items like panels that the TDMS can easily replicate, and save money on, have to be taken.


OK, so does it matter?

Well, to be frank, on day one of operations; not at all.


As long as the TDM has done a good job and accurately replicated everything, including the feel of switches, there should be no training or qualification issues. The TDM can enjoy the improved margins and the operator the lower acquisition cost.


But let’s go back to the customer we have been helping recently who wanted to refurbish the flight deck of their FFS. First thing we find is that a lot of the parts, including the back lit panels, are replicated parts and the operator has no spares. After all, who in their right mind spares every single panel and switch; who has the budget? Then we find the manufacturer of the device is no longer trading. Checking the documentation package for the device, not surprisingly, there are no detailed drawings. So there is now no option but to remove the panels to be reworked and try to get by with photographs in the interim. Whereas if they had been aircraft parts we could easily source replacements from the aftermarket and aircraft manufacturers/OEMs rarely cease trading!


So what’s the answer?

Well actually we don’t believe there is a single answer, which is why the debate continues. It comes down to “you pay your money and you take your chance”. We all know that some panels in a flightdeck will last the life of the device hardly ever being used whereas some panels get more usage on an FSTD so if you are going down the replicated route it might be wise to spare these (we know of one customer who specified the “N”, “S”, “E” and “W” buttons from their replicated FMS CDUs in their spares pack; they weren't wrong to do so).


There are other practical things you can do, for example; if your TDM is supplying you replicated parts, insist on receiving dimensioned drawings of these and any firmware. It is also a good thing to contact other operators so that you can pool spares and solutions. There are options available and companies who can make replacements, but there may be hoops to jump through on the way.


How can Sim Ops Help?

At Sim Ops our we can help you ensure that at the point of purchase this issue is addressed contractually and pragmatically. We can also assist on the strategy of defining which parts to spare if your TDM is going down the replicated path. And if everything goes wrong can find solutions for worn parts, either through refurbishment or replacement parts.


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