Abstract: An inlet door system includes a duct, an inlet door, and a plurality of openings. The duct is configured to extend from the auxiliary power unit (APU) to an intake opening formed in an outer surface of an aircraft. The duct includes an inlet port, an outlet port, and a duct sidewall extending between the inlet port and the outlet port. The inlet door includes an inner surface, an outer surface, and an outer peripheral edge between the inner and outer surfaces. The door is rotationally coupled to the duct, and is configured to selectively rotate between a closed position and a plurality of open positions. The openings extend through the inlet door between the inner surface and outer surface, and each opening is disposed adjacent to the outer peripheral edge.

Abstract: An inlet door system includes a duct, an inlet door, and a plurality of openings. The duct is configured to extend from the auxiliary power unit (APU) to an intake opening formed in an outer surface of an aircraft. The duct includes an inlet port, an outlet port, and a duct sidewall extending between the inlet port and the outlet port. The inlet door includes an inner surface, an outer surface, and an outer peripheral edge between the inner and outer surfaces. The door is rotationally coupled to the duct, and is configured to selectively rotate between a closed position and a plurality of open positions. The openings extend through the inlet door between the inner surface and outer surface, and each opening is disposed adjacent to the outer peripheral edge.

Abstract: Assemblies for cooling an aft bearing assembly mounted to a rotor are provided. An assembly includes a static aft bearing structure configured to surround the aft bearing assembly and including a cylindrical section defining a cavity for disposal of the aft bearing assembly, a plurality of hollow struts extending from the static aft bearing structure, each hollow strut including an outer radial end configured to receive a gas from an air source and to provide a pathway for the gas to flow into the cavity, and a center-body cap disposed over an end of the static aft bearing structure, the center-body cap including a rim configured to create a low pressure region at an interface between the static aft bearing structure and the center-body cap, wherein the low pressure region has a pressure that is lower than a pressure within the cavity.

Abstract: An insulation assembly for use with an APU having an exhaust muffler is disclosed herein. The insulation assembly includes, but is not limited to, a first insulating member that is configured for placement on a top portion of the exhaust muffler and a second insulating member attached to the first insulating member and configured for placement on a bottom portion of the exhaust muffler. The second insulating member is less resistant to heat transfer than the first insulating member.

Abstract: An insulation assembly for use with an APU having an exhaust muffler is disclosed herein. The insulation assembly includes, but is not limited to, a first insulating member that is configured for placement on a top portion of the exhaust muffler and a second insulating member attached to the first insulating member and configured for placement on a bottom portion of the exhaust muffler. The second insulating member is less resistant to heat transfer than the first insulating member.

Abstract: Assemblies for cooling an aft bearing assembly mounted to a rotor are provided. An assembly includes a static aft bearing structure configured to surround the aft bearing assembly and including a cylindrical section defining a cavity for disposal of the aft bearing assembly, a plurality of hollow struts extending from the static aft bearing structure, each hollow strut including an outer radial end configured to receive a gas from an air source and to provide a pathway for the gas to flow into the cavity, and a center-body cap disposed over an end of the static aft bearing structure, the center-body cap including a rim configured to create a low pressure region at an interface between the static aft bearing structure and the center-body cap, wherein the low pressure region has a pressure that is lower than a pressure within the cavity.