L2 engine fail towards idle
Lonewolf, you need to be familiar with the Norwegian Norne accident some years ago (that has been mentioned earlier in this thread) but basically, some damage was acruing in the high speed shaft caused by a loose nut (IIRC), this took out all N2 signals the engine ran up, then the damaged shaft failed and the turbine suffered a massive overspeed that caused fragments of the disc to sever the flight controls, take out the other engine, and kill some passengers before they hit the water.
As a result, the failure mode of the engine was made more benign - ie running to idle is better than an uncontained N2 overspeed especially in a twin.
The 332L and L2 have a manual emergency throttle so that, following such a run-down, the crew can advance the throttle to restore some (ungoverened) power on that engine.
I should add that its a pretty unlikely set of conditions that have to be met to make the engine run down, and its not something that happens often, if at all.
Last edited by HeliComparator; 26th Aug 2013 at 17:20.