Twin engine helicopters - allowable engine ground surging
I thought about the Rotorhead forum but decided you folks were my best bet.
For you guys / gals that look after twin engine helicopters, what do the individual manufacturers allow in their manuals for ground surging, as a percentage of N1, NG or whatever the nomenclature.
I have been asked a question at my place of employment and am interested in the values stipulated by Sikorsky, Bell etc
I think that the engines naturally will try to fight each other which can lead to "hunting" or small amounts of surging, just trying to see how much is allowed since we have no stipulated limits that I can find EXCEPT none allowed in flight.
Thanks in advance.
PT6ER