Patent ID: 7210652

Claim:
A method for reducing APU noise from an APU located within an aircraft housing by an inlet door assembly during aircraft in-flight and ground operations, wherein the inlet door assembly comprises a duct having an inlet port, an outlet port, and a flow passage therebetween through which APU noise propagates, a door having a forward and an aft side, the door rotationally mounted on the duct and configured to selectively rotate between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction, an actuator coupled to the door, the actuator further comprising an arm having first and second ends, the arm first end rotationally mounted to the duct, the arm second end configured to move into and out of the flow passage, the arm second end coupled to the door, wherein the actuator is configured to selectively raise and lower the door relative to the aircraft housing and rotate the door between at least the first and second positions, the method comprising: raising the arm relative to the aircraft fuselage to thereby raise the door and open the inlet duct; rotating the door forward side proximate the aircraft fuselage, during aircraft ground operation; and rotating the door aft side proximate the aircraft fuselage, during aircraft in-flight operation.