Np spikes? Anyone experienced this.
 

Have any small / GA pilots have had issues with Np indications having indicated momentary highs?
I have heard of issues with a few Np tacho generators. The prop isn't hunting, all other gauges fine, just momentary highs in the Np.
There has a been deep fault finding, and seems to come back to a single batch of tacho generators. They are used on many engines, so in this case assume it was on a turboprop.
Please, leave replies to folk who have actually seen this in flight.
Thanks in anticipation of a flood of replies.

Np is propeller RPM.

Such gauges are only found on turboprops, on piston engines the prop RPM is either the same as the engine RPM or geared down by a fixed ratio so we are only interested in engine RPM.

IOW - you are asking in the wrong forum, turboprop jockeys are found in the Business Aviation areas.
http://www.pprune.org/biz-jets-ag-flying-ga-etc-36/