System and method for operating a multi-engine aircraft in an auxiliary power unit mode

摘要

A first and second engine (10 1 , 10 2 ) are connected to a drive train (110 1 , 110 2 ) for driving an aircraft accessory (108). A gearbox (106) is connected to a primer mover propulsor (102, 104). An actuator, operatively associated with a selected engine (110 1 , 110 2 ) is moveable between a position in which the selected engine (110 1 , 110 2 ) drivingly engages the gearbox for driving the propulsor (102, 104) and a position in which the selected engine (110 1 , 110 2 ) disengages from the gearbox (106). A position signal, a status signal, and a request signal that are respectively indicative of a present position of the actuator, a governing state and present speed of each engine, and a request for movement of the actuator from the present position to the other position are received. If the selected engine's speed differs from a predetermined threshold, a control signal is output for causing the engine's speed to be adjusted towards the threshold. A control signal indicating that movement of the actuator is permitted is then outputted.