Dual action inlet door and method for use thereof

An inlet door assembly for reducing noise from an auxiliary power unit (APU) contained within an aircraft having a forward end and an aft end, the inlet assembly comprising:

• a duct having a sidewall including a forward wall and an aft wall and defining an inlet port, an outlet port, and a flow passage therebetween through which APU noise propagates;
• a first door rotationally mounted on the forward wall of the duct and having an inner surface facing the duct flow passage and an outer surface forming an exterior of the aircraft, the first door configured to selectively rotate between at least a first position, in which at least a portion of the inner surface of the first door deflects the APU noise in a first direction toward the aircraft aft end, and a second position, in which at least a portion of the inner surface of the first door deflects the APU noise in a second direction into the duct flow passage;
• a second door rotationally mounted on the aft wall of the duct proximate the first door and having an inner surface facing the duct flow passage, the second door configured to selectively rotate between at least a third position when the first door is in the first position, the third position in which at least a portion of the inner surface of the second door deflects the APU noise in a first direction toward the duct flow passage, and a fourth position when the first door is in the second position, the fourth position in which at least a portion of the inner surface of the second door deflects the APU noise in a second direction toward the outer surface of the first door;
• and
• an actuator coupled to the first and second doors and configured to rotate the first door to at least the first and second positions and to rotate the second door to at least the third and fourth positions.