Series of problems upon descent

[Demious 23]

I just made a flight from EKAH to ENZV and during the RIVEX1T STAR I first got problems with my left engine, I got a #1PEC caution warning and the left engine power started to jump up and fall down. When, after a few minutes, the engine power stabilized again the prop RPM was still about 200RPM too high, at the top of the yellow arc, but the aircraft seemed to fly properly. Up until ZV732 descent seemed to go as planned and the aircraft went down to 7000ft, but when it had to descent to 3000ft for ZV731, the aircraft dived down with 4000ft/min and didnt pull up to level off at 3000ft with a Pitch Hold on the MFD and dived straight into the ground.

 

I still got a lot to figure out for this aircraft and I dont have a clue what happened here. If someone could enlighten me about what's going on and how to deal with it would be greatly appreciated.

[ckyliu 1,749]

If you accidentally move the condition levers in to feather (which is very easy, sometimes they jump straight from max to feather, depending how you've calibrated them in the MJC8CPan) it will often cause PEC failure.

 

I've found the fix is to quickly pop the condition levers to shut off, then quickly move them back to full before the engine turns off and that usually resets the PECs and gives me propeller RPM control back - but of course this is a bit Russian roulettey as you might accidentally turn the engines off altogether!

 

The below is from torkermax and explains in a bit more detail what's happening:

This is a feature present on the actual aircraft, the AUPC (automatic underspeed protection circuit) prevents prop underspeed while inflight with autofeather off and CL above start/feather. If the system detects RPM below 816, while torque above 50% for 1 second, the Props will be sent into an overspeed condition with the PEC caution lights coming on. If your setting cruise power to MIN but you accidentally skip the detent and go to START/FEATHER and then back to MIN, as someone indicated above having mouse trouble with the levers, you can create all the conditions for this to happen. It has happened to a few RW airlines and they were only able to clear the overspeed after they landed.

[Demious 23]

Thanks for the info, Chris. I'll have a look at it, but this indeed seems to be what just happened to me.

[crosswind 825]

Normally a PEC caution light followed by the associated engine(s) RPM indicating 1060 is indicative of moving the condition levers below the MIN detent.  If this situation occurs, the required way to resolve this is to shut down the engine and re-light it.