I hope the people at Airbus are taking a long hard at what caused the computers to all fail at pretty much the same time - that's probably
not a coincidence - there is some unknown common failure going on.
We had an issue several years ago with the CF6-80C2 FADEC. There was an in-flight shutdown - and when I looked at the data it very much appeared that both FADEC channel CPUs failed at the same time (or within one second, since that was the data recorder frequency). Now, while that is theoretically possible, the odds are astronomical - in fact our engine controls Tech Fellow went so far as to say it was impossible. But with nothing else to go on I figured it was a freak occurrence. But then there were several other shutdowns with the same symptoms (IIRC we ended up with 7 total shutdowns due to that cause). GE was finally able to track it down - it was an Electro Magnetic Interference (EMI) effect when continuous ignition was commanded on. Turns out there had been several hardware changes and a software change over the previous 10 years that combined to give the susceptibility
.
The real concern was it was a potential common cause failure since continuous ignition is commanded when the flaps are lowered during approach. Fortunately the actual probability of Con Ignition 'ON' causing a shutdown was quite low so the odds of a multiple engine event were in the 10-9/flight range, but it was still worrisome (and you know what they say about statistics
). The FAA quickly issue an AD that dictated 'depairing' of suspect FADECs (i.e. you could only have one FADEC with that particular combination of software and hardware configuration per aircraft), and I slept better after we got a fix certified and retrofit into the fleet.