Is the new double-decker Airbus vulnerable to sudden drops in cabin pressure? That’s the kind of problem suspected in this summer’s crash of a Helios Airways plane that killed all 121 people on board.
The former chief engineer for the company that designed the microchips controlling the motors that runs the pressure valves thinks so. The company, TTTech Computertechnik AG, of Vienna, fired him for going public with his concerns. For good measure, it has sued him in both civil and criminal court. Austria has no laws to protect whistleblowers.
When a plane is cruising at 30,000 feet or so, valves controlling intake and release of air maintain a cabin pressure that keeps everyone on board alive. Sudden loss of pressure could cause people, including pilots, to lose consciousness in a matter of seconds. According to the Los Angeles Times,
Most passenger jets have two cabin-pressure valves, with separate motors operating each. Because aircraft makers want redundancy on safety systems, the planes have three motors for each valve, with different chips controlling each motor. The Boeing 777, for example, has cabin-pressure chips made by Motorola Inc., Intel Corp. and Advanced Micro Devices Inc. Most jetliners also have a manual override so that the pilot can take control in an emergency.
Three motors per valve, different chip for each motor, just in case. Airbus took a different route:
Airbus has acknowledged that its designers faced challenges as they attempted to reduce the A380’s weight. Early on, the company elected to go with four outflow valves on the A380, with only one motor on each valve, which is slightly larger than a cabin window. Each motor uses a TTTech controller chip, and there is no manual override system.
Airbus says that having four valves is sufficient redundancy. To me, it seems that if there is a problem with the type of chip that controls all four, then it’s same problem repeated four times, and no redundancy at all.
The Times talked with an Airbus spokesman:
“Don’t you think we would look into it, and if we found it was true we would do something about it?” [Airbus spokesman Clay] McConnell asked.
This is the sort of thing that big corporate spokesmen have to say. Unfortunately, the less specific the assertion, the less credibile it looks. And there’s a long line of assertions by corporate flacks that have turned out to be dead wrong. (There’s of course the cynical take that the companies involved did do something: Mangan was fired and has been sued into near bankruptcy and still faces jail time in Austria. No more whistleblower, no more problem.)
Cost is clearly an issue: TTTech’s web site trumpets “Aerospace Safety at Automotive Cost.” Both the consortium and the company want to get the chips in question certified as off-the-shelf parts suitable for airplane usage. Mangan says that the chips have been customized for airline use and have to undergo stringent, and costly, testing. Nobody the Times spoke with seemed to be able to answer with any certainty, and the statements from officials were tellingly bland.
The Times cited court records showing that TTTech had offered to drop the suits and give Mangan three months’ severance pay if he would retract his statements. He would not.