Originally Posted by
lucille
Xeptu, correct me if I’m wrong..it’s been 40 years since I fiddled with a 331.
My memory of the NTS system is that it cycles the blade angle between feather and some other blade angle to minimise drag - where drag is the condition when the airflow is driving the engine.
The idea being that this feature buys the pilot time to recognise the failed engine and feather it.
I don’t understand how NTS, if working as intended, would flip anything on its back anymore than say stalling an aircraft with the operative engine producing power.
Is it possible that the fidelity of the simulator in question may be lacking at that extreme corner of the envelope?
No not at all. The Negative Torque Sensing System NTS senses negative torque that zone from full fine going into beta reverse range, there are no fine pitch stops other than mechanical locking pins used to hold the blade in fine pitch for on ground starting, min drag. you then pull reverse to to allow the locks to throw out by centrifugal force.
In flight when you reduce to flight idle thus reducing blade angle toward fine, the NTS senses if the blade angle has gone too far and directs oil pressure to the hub to coarsen the blade angle in order to keep it in the flight range. A light for each propeller illuminates to warn you that the NTS system is sensing negative torque and is doing its job.
Does that explain the system without getting too technical.