Long term support for aerospace projects is getting harder...

Author : Pete Warnes | Business Development | Dotstar Design

02 July 2019

dotstar circuit board
dotstar circuit board

With extended design cycles & operational life of aircraft, designers must be assured that parts they design in can be sourced for long periods. As Pete Warnes, experienced electronics design specialist working with Dotstar Design explains, 10 years is a minimum – and in the end, support will likely be required for multiple decades.

This article was originally featured in the July 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.

Mechanical parts will probably be custom machined, so will be manufacturable into the future, but modern aircraft have more and more electronics incorporated in them. Even custom-designed electronics will use ‘commercial off-the-shelf’ (COTS) components. And the electronics world today moves much more rapidly than a 10 year lifespan. Many electronic components that were commonplace 10 years ago are simply no longer available.

Back in the 80s, I worked on Military electronics design, and we were not allowed to design in the ‘latest’ components, because they had to be properly qualified and have reliability statistics before they could be approved for use. I am sure that it is many times more difficult for designers of avionics today, but that they are well versed in what is required.

But there are some areas where the fast changing technology and need for long support can cause issues that were not necessarily even considered – the avionics will need to be inspected and tested. Can the test systems themselves be supported for tens of years? Will the computer peripheral bus still be supported? How about the operating system?

Dotstar Design helped Airbus Helicopters on a project for one such test system. The support for the actual avionics is all taken care of, but the test system used a COTS product that can no longer be manufactured, because the components are mostly obsolete. What’s more, it uses an I/O bus that is no longer supported by any computer, and an operating system that can no longer be purchased or supported. To help the client cope with this, Dotstar designed a combination of hardware and software that can be manufactured and supported for at least 10 more years – and is a direct replacement for the old system.

To do this, we chose modern components that we ‘hope’ will still be available for many years to come – but actually, most of the system functionality was implemented in FPGA, so that even if that component is no longer available, the firmware can be re-used on a different FPGA. This meant we had to be careful not to use any really specific features of the FPGA architecture, so that it will be easily portable.

Despite the hardware using a completely different I/O bus, the firmware that we are providing is being coupled with device drivers that provide precisely the same interface as the obsolete system. This allows a smooth transition to the new system, which can now be supported well into the future. Fortunately, the actual test software they have is already written in Generic C code that can be re-compiled today.

This approach is also necessary for many applications outside of the aerospace industry – for instance, we’ve been talking to a customer who uses ADSL to transmit data within their systems. It seemed like a great solution at the time, but they can no longer buy the cards or chipset that they use. We are offering to emulate that system for them in FPGAs too...

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