Patent ID: 11939914
Assignee: PRATT & WHITNEY CANADA CORP.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 9:
10. A system for operating a multi-engine system of an helicopter, the multi-engine system having a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, and a gearbox having a clutch system clutching at least one of the first shaft and the second shaft to a load of the helicopter, the first and second shafts having a range of rotation speeds defined as a placarded zone, the system comprising:
a processing unit; and
a non-transitory storage medium having stored thereon program code executable by the processing unit for:
simultaneously i) rotating the first shaft at a flight rotation speed when the first shaft is clutched to the load and ii) rotating the second shaft at a first idle rotation speed when the second shaft is unclutched to the load, the first idle rotation speed below the flight rotation speed and above the placarded zone;
decreasing a rotation speed of the first shaft from the flight rotation speed to a given rotation speed within the placarded zone;
decreasing a rotation speed of the second shaft from the first idle rotation speed to the given rotation speed within the placarded zone;
clutching the second shaft to the load when the rotation speed of the second shaft reaches the given rotation speed within the placarded zone; and
simultaneously decreasing the rotation speed of the first shaft and of the rotation speed of the second shaft to a second idle rotation speed below the placarded zone when the first shaft and the second shaft are clutched to the load.