S76 OEI N2/Nr Droop
Hi all,
With reference to the S76, fitted with Arriel engines, no DECU/FADEC etc:
Two engine N2/Nr is set at 107%. If one engine's power is removed, and with the remaining engine within limits, it seems to droop and stabilise at around 104-105%.
Each engine doesn't know whether the other one is functioning or not, so I view the loss of one engines power simply as an increased demand of the other one providing power, similar to raising the collective in a single.
My understanding is that if you ask an engine to deliver 107% N2/Nr, the engine will do everything it can to give you that, including maximum fuel flow (N1 topping) if need be.
I can't quite seem to get my head around why this droop happens.