Originally Posted by Mountainbear
I went back and read the reports to refresh my memory. I don't know where you get the idea the the design of the ADIRU was supposed to isolate the spurious signals, but that's wrong too.
As for whether the ADIRU was a dud the 2nd Interm report clearly states it was not.
I didn't say that the design of the ADIRU was supposed to isolate signals. I said "the system" didn't isolate the signals. Read my lips. Given your "no fault found" comment, you obviously have little real-world aviation experience, especially with computerised aircraft.
To put your mind at rest, that I was telling the truth, I quote from one of the ATSB reports (Interim factual tab on
this page):
The investigation to date has identified two significant safety factors related to the pitch-down movements. Firstly, immediately prior to the autopilot disconnect, one of the air data inertial reference units (ADIRUs) started providing erroneous data (spikes) on many parameters to other aircraft systems. The other two ADIRUs continued to function correctly. Secondly, some of the spikes in angle of attack data were not filtered by the flight control computers, and the computers subsequently commanded the pitch-down movements.
As I said: ADIRU 1 sent dud signals to the system (FCCs), which didn't compare dud signals with the two sets of good signals and then made the aircraft uncontrollable - twice.