Originally Posted by
SASless
If one runs with the un-contained catastrophic engine failure causing a high and increasing TOT.....what would you expect the N1/NG to be?
Would moving the ECL to Idle have any effect?
Now that causes me to remember another accident where there are a lot of parallels. It was an EC145 (same cockpit with CPDS) but different engines. There were two incidents where an oil pipe got blocked by coking (insufficient cool down post flight) and oil was starved from a rear bearing on the engine. The bearing temperature went through the roof from friction and one symptom was a TOT rise without any appreciable change in either N1 or torque. The first incident resulted in an engine fire (first parallel) (see here -
EC145 has seized bearing leading to engine fire. The second resulted in an engine failure (see here
Loss of EC145 following loss of oil and rapidly rising TOT) - it was significantly made worse because the pilot shut down the wrong engine.
The EC135 FLI on the CPDS is uniquely misleading if you have a runaway TOT and you bring the "good" engine back to idle - it looks like you've done the right thing (the extreme TOT AEO is suddenly not so extreme OEI). You have now loaded up the bad engine and it fails. Very easy to demonstrate on a EC135 simulator.
So I think a blocked oil pipe and seized bearing is a possible culprit (or an uncontained runaway up - although the pilot would almost certainly have commented on this).