Alliedsignal Inc.

John K Harvell

Ray McGinley

Joseph W Michalski, Jr

Robert C Wagner

Craig A Freeman

For gas turbine engine mounted in an aircraft, a closed loop control system, and method therefor, for the inlet duct is provided. Under this control system the flow area of the inlet duct is varied by opening and closing a duct door. The control assures that the position of the door is such that the delta P across the engine will not inhibit the starting of the engine in flight.

Method and apparatus for controlling the inlet duct leading to an auxiliary power unit

A start circuit controlled by an electronic control unit for providing power from one or both of a battery and TRU in parallel to a starter motor coupled to a gas turbine engine. The circuit includes contactors between the TRU and battery and a junction where the current from the TRU and battery combine. The circuit further includes two additional contactors in series between the junction and the starter motor. Voltage sensors and contactor position sensors are employed for diagnostics. A novel method of starting the engine using the start circuit contemplated by the present invention is also descibed. In this method, the start is initiated with power only from the battery. After a period of time power from the TRU is added. This method reduces the amplitude of the start motor inrush current, which has a beneficial reliability effect on the components of the start circuit.

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Phoenix, AZ, United States of America

John K Harvell