US 11,939,914 B2
System and method of operating multi-engine system
Philippe Beauchesne-Martel, Brossard (CA); Gaetan De Lussy, Montréal (CA); Jeremie Hebert, Napierville (CA); and Daniel Coutu, Longueuil (CA)
Assigned to PRATT & WHITNEY CANADA CORP., Longueuil (CA)
Filed by PRATT & WHITNEY CANADA CORP., Longueuil (CA)
Filed on Dec. 2, 2021, as Appl. No. 17/540,576.
Prior Publication US 2023/0175436 A1, Jun. 8, 2023
Int. Cl. F02C 6/20 (2006.01); B64D 27/10 (2006.01); B64D 31/00 (2006.01); F02C 6/02 (2006.01); F02C 9/42 (2006.01)
CPC F02C 6/02 (2013.01) [B64D 27/10 (2013.01); B64D 31/00 (2013.01); F02C 6/20 (2013.01); F02C 9/42 (2013.01); F05D 2220/329 (2013.01); F05D 2260/96 (2013.01); F05D 2270/02 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method of 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 method comprising:
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.