Do you have the same issue if you follow the OP’s steps to reproduce it?
I have done more research on the Pratt & Whitney PW1xx series engines, and it seems that this engine series’ EEC incorporates a taxi/ground operation mode (“bottom governing”) that maintains or limits the prop RPM while the Power Levers are in the normal ground range. Bottom governing means that governor operation is reversed, so RPM is maintained by fuel flow, and the PLs control beta (positive AND negative beta). This is also typical of other turboprops in the commuter category, and larger.
Basically, the MSFS ATR’s engines will rev the prop RPM to 100% with a small power increase during taxi and this is not realistic. Prop RPM should be maintained around the ~72% mark until the PLs are advanced past a certain mark during taxi and landing rollout.
I have started turning the PWR MGT knobs to CLB while I am taxiing around (limits the NP to 82%). Of course this is not correct, but it makes taxiing much smoother because you are not dealing with big surges of prop RPM between 72% and 100%.
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