"Sudden catastrophic loss of power"
Witnesses reporting a sudden loss of power - whilst this should be taken with a pinch of salt in the short term, I was pondering possible causes.
In the DECU there are some bits of software whose sole purpose is to make the engine run down to idle under certain fault conditions. This came about following the Norwegian Norne accident mentioned earlier in this thread. I'm trying to remember (since I've been away from the L2 since 2006) what the triggers are:
Double Nf sensor failure
Faulty PPNg signal
Major DECU hardware failure
Anything else? I think there is, but can't remember. Anyone out there with their L2 groundschool notes?
Obviously it would need to happen to both engines simultaneously, so a common trigger would have to be involved which at first sight seems unlikely.
On the other hand, when one engine runs down, the other is put under the sort of stress it never normally sees, especially after CHC's policy of not conducting OEI training in the aircraft due to freewheel concerns.
As an aside, this is the sort of area where technological progress helps. On the 225, any of a double N1 sensor failure, double N2 sensor failure and pretty much any double failure you can think of, has no major impact on power. Even a complete governing failure (which has never happened) results in a fuel flow freeze, a much more benign failure than the engine running down to idle.
Last edited by HeliComparator; 26th Aug 2013 at 08:16.