Np spikes? Anyone experienced this.

[Kinger]

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.

[The Ancient Geek]

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/