Patent ID: 11920479
Assignee: PRATT & WHITNEY CANADA CORP.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  B  Y | IPC B  F

Claim 8:
9. A method of operating a multi-engine system of a rotorcraft, the multi-engine system including a first engine, a second engine, and a gearbox drivingly coupling the first and second engines to a rotor of the rotorcraft, the method comprising:
during a cruise flight segment of the rotorcraft, controlling the first engine to provide a first power output, the first power output driving the rotor via the gearbox to maintain the cruise flight segment; and
during the cruise flight segment of the rotorcraft, controlling the second engine to operate in a standby mode without decoupling the second engine from the gearbox, wherein the second engine provides a second power output to the gearbox that is less than the first power output of the first engine, the second power output of the second engine when operating in the standby mode being greater than 0% and less than 1% of a rated full-power of the second engine with the second engine operating at a rotational speed lower than an idle speed of the second engine, and controlling the second engine to operate in the standby mode by providing a fuel flow to the second engine that is between 80% and 99.5% less than a fuel flow provided to the first engine when the first engine is providing the first power output;
wherein the second engine includes a low pressure spool having a low pressure compressor and a low pressure turbine section, the low pressure compressor section including a mixed flow rotor, a set of variable guide vanes being upstream of the mixed flow rotor, the second engine including a high pressure spool having a high pressure compressor and a high pressure turbine section, the low pressure spool and the high pressure spool being independently rotatable relative to one another, and a second set of variable guide vanes (VGVs) located upstream of the high pressure compressor, the set of VGVs and the second set of VGVs being independently operable relative to one another, and wherein the step of controlling the second engine to produce the second power output includes modulating the set of VGVs and the second set of VGVs to permit the fuel flow to the second engine of between 80% and 99.5% less than the fuel flow provided to the first engine.