Archive for the ‘Engineering’ Category

The Challenges of Designing Electronics for the Aviation Industry

March 4, 2008
You are probably wondering how a tiny electronics firm from Calgary got involved in designing first class passenger seat systems for the aircraft industry. The short: Timing and luck! Her is a brief history. Back in 1998 I was working with Innovage Microsystems in Calgary who had designed a clip-on microprocessor tester that was used to test the microprocessors while running. A small company, “Boeing” had expressed an interest in the product for testing the multiple processors on their aircraft. In working with Boeing, Innovage learned that a seat manufacturer was building first class lie-flat sleeper seats and had no way of testing the finished seats or the seat electronics. When the controller manufacturer said there was no way to test the seats, Innovage jumped at the opportunity and brought me in as a consultant to design a “test interface box (TIB)”. Within two years, the TIB was installed and flying!

Designing for the airline industry present a whole lot of unique challenges. Software must be carefully monitored using version control and meet DO178-B safety standards. The FAA established DO178-B as the accepted means of certifying all new aviation software. The targeted DO178 certification level is either A, B, C, D, or E. Correspondingly, these DO178-B levels describe the consequences of a potential failure of the software: catastrophic, hazardous-severe, major, minor, or no-effect. The cost to test and certify safety critical software is directly proportional to the level of safety criticality. This can quickly drive you design cost sky high.

Hardware presents similar challenges and must meet the requirements set out by the FAA DO160 specifications. This standard defines a series of minimum standard environmental test conditions and applicable test procedures for airborne equipment. The purpose of these tests is to determine the performance characteristics of airborne equipment in environmental conditions representative of those which may be encountered in airborne operation of the equipment. Temperature, humidity, vibration, lightning and EMI are just a few of the test parameters. Manufacturing must also meet rigorous standards with every part; every resistor, capacitor or screw must be traceable back to the manufacturer.

In the final seat design, wire routing and serviceability of components must also be carefully considered. When an aircraft lands, there is only a 4-hour window to fix or replace faulty components. Electronic systems now have Built-In-Test capability that identifies component failures. This information is passed along to the ground while the aircraft is still in the air so that the maintenance crews have the parts and equipment ready to repair the systems as soon as the aircraft lands.

One of the many challenges of designing systems for aircraft was highlighted during a demonstration of a seat and suite to one of the airline representatives. The suite had been designed for installation on the Airbus A380. The demo was for the installation of the suite on the Boeing 777. The suite included a small closet that opened into the aisle. The airline representative asked if the hinges on the closet door could be switched to the other side to allow for easier access. I thought that this should not be a big issue however it was quickly pointed out that the way the closet door swung into the aisle may impede the exit of passengers in an emergency. The change would have to be carefully reviewed with respect to the location of emergency exits on the different aircraft! This meant new drawings, new approvals and associated costs.

I hope this article has enlightened you on a few of the challenges in designing system for the aviation industry. At least you should have a better understanding why a screwdriver can cost $300!

November 1, 2007 | Unregistered CommenterKen Stewart-Smith