Engine failure monitor for a multi-engine aircraft having partial engine failure and driveshaft failure detection

An engine failure monitor for detecting an engine failure in a multi-engine aircraft having at least two engines each of which includes a free turbine for driving an engine driveshaft and being operated in dependence on the angle of a power lever, each engine associated with a respective engine failure monitor constituting a local engine, and each remaining engine constituting a remote engine, comprising:

• means for providing a local engine torque signal indicative of an output torque of said local engine (QLOC);
• means for providing remote engine torque signals indicative of an output torque of said remote engine (QRMT);
• means for providing a flight detent signal in response to said power lever being at an angle (PLA) between a first value and a second value;
• and
• said engine failure monitor being responsive to a simultaneous occurrence, for a period in excess of a first threshold period, of said flight detent signal, and one of said remote engine torque signals exceeding said local engine torque signal by a first threshold value for providing a partial engine failure signal indicative of partial failure of said local engine.

A method of detecting an engine failure in a multi-engine aircraft having at least two engines each of which includes a free turbine for driving an engine driveshaft and being operated in dependence on the angle of a power lever, each engine associated with a respective engine failure monitor constituting a local engine, and each remaining engine constituting a remote engine, the method comprising the steps of:

• providing a ground idle signal in response to said power lever being at an angle (PLA) above ground idle for said local engine;
• providing a local turbine shaft speed signal indicative of turbine shaft speed (NFLOC) of said local engine;
• providing a rotor speed signal indicative of main rotor speed (NR);
• providing a turbine shaft rate signal indicative of a rate of change in turbine shaft speed (NFDOT) of said local engine;
• and
• signaling a local engine driveshaft failure in response to a simultaneous occurrence, for a period in excess of a first threshold period, of said ground idle signal, said local turbine shaft speed signal exceeding said main rotor speed signal by a first threshold value, and said local turbine shaft rate signal being in excess of a second threshold value.

A method of detecting an engine failure in a multi-engine aircraft having at least two engines each of which includes a free turbine for driving an engine driveshaft and being operated in dependence on the angle of a power lever, each engine associated with a respective engine failure monitor constituting a local engine, and each remaining engine constituting a remote engine, the method comprising the steps of:

• providing a local engine torque signal indicative of an output torque of said local engine (QLOC);
• providing remote engine torque signals indicative of an output torque of said remote engines (QRMT);
• providing a flight detent signal in response to said power lever being at an angle (PLA) between a first value and a second value;
• and
• signaling a partial failure of said local engine in response to a simultaneous occurrence, for a period in excess of a first threshold period, of said flight detent signal, and one of said remote engine torque signals exceeding said local engine torque signal by a first threshold value.