Aircraft with disengageable auxiliary power unit components

Abstract

Several improvements to an aircraft turbine engine and Auxiliary Power Unit (APU) are disclosed, as well as methods of using these improvements in routine and emergency aircraft operations. The improvements comprise the addition of cockpit-controllable clutches that can be used to independently disconnect the engine's integrated drive generator (IDG), engine driven pump (EDP), fuel pump, and oil pump from the engine gearbox. These engine components may then be connected to air turbines by the use of additional clutches and then powered by the turbines. Similar arrangements are provided for the APU components. Cranking pads, attached to various engine and APU components, are disclosed to provide a means for externally powering the components for testing purposes and to assist with engine and APU start. Detailed methods are disclosed to use the new components for routine ground-testing and maintenance and for the enhancement of flight safety, minimization of engine component damage, and extension of engine-out flying range in the case of an emergency in-flight engine shutdown.

1 . An aircraft auxiliary power unit (APU), comprising an APU compressor, an APU combustor, an APU turbine connected to the APU compressor by an APU main shaft, and an APU gearbox fitted with:
 an APU oil pump normally connected to the APU gearbox;   a fuel control unit (FCU) connected to and driven by the APU oil pump;   an APU starter-generator operatively connected to the APU gearbox; and   an APU hydraulic pump operatively connected to the APU gearbox.   
     
     
         2 . The aircraft auxiliary power unit (APU) of  claim 1 , wherein:
 the APU oil pump includes an APU oil pump clutch, which can be controlled to disconnect the APU oil pump with or disconnect the APU oil pump from the APU gearbox, such that the APU oil pump is normally connected with the APU gearbox and the APU oil pump can be disconnected from the APU gearbox for ground test and troubleshooting of the APU oil pump; and   the FCU includes an FCU cranking pad, which allows a motor to drive the APU oil pump through the FCU when the APU oil pump is disconnected from the APU gearbox for ground test and troubleshooting the oil pump/APU oil system and the FCU/APU fuel system without running the APU in its entirety.   
     
     
         3 . The aircraft auxiliary power unit (APU) of  claim 1 , wherein the APU starter-generator includes:
 a starter-generator clutch which can be controlled to connect the APU starter-generator with or disconnect the APU starter-generator from the APU gearbox, such that the APU starter-generator is normally connected with the APU gearbox and the APU starter-generator can be disconnected from the APU gearbox for ground test and troubleshooting of the APU generator;   an APU starter-generator cranking pad which allows a motor to drive the APU starter-generator when the APU starter-generator is disconnected from the APU gearbox for ground test and troubleshooting of said APU starter-generator without running the APU in its entirety;   a turbine clutch which can be controlled to connect the APU starter-generator with or disconnect the APU starter-generator from an air turbine, such that the APU starter-generator is normally disconnected from the air turbine and
 when the APU starter-generator is disconnected from the APU gearbox, the APU starter-generator can be connected with the air turbine for the air turbine to drive the APU starter-generator to provide back-up electrical power in certain flight emergency cases and abnormal conditions and as a means to test and troubleshoot on the ground the APU starter-generator and its system without running the APU in its entirety; and 
 when the APU starter-generator is connected with the APU gearbox, the APU starter-generator can be connected with the air turbine for the air turbine to drive the APU through the APU starter-generator and APU gearbox as back-up starter on ground and in flight; and 
   a compressor clutch which can be controlled to connect the compressor with or disconnect the compressor from a turbine, such that the compressor is normally disconnected from the air turbine and, regardless of whether the APU starter-generator is connected with the turbine or the APU gearbox, the compressor can be connected with the turbine for the turbine to drive the compressor to provide compressed air for air conditioning and anti-ice system in certain abnormal flight conditions and emergency cases and as a means to test and troubleshoot the air conditioning system on the ground without running the APU or the gas turbine engine entirely.   
     
     
         4 . The aircraft auxiliary power unit (APU) of  claim 1 , wherein the APU hydraulic pump includes:
 a hydraulic pump clutch which can be controlled to connect the APU hydraulic pump with or disconnect the APU hydraulic pump from the APU gearbox, such that the APU hydraulic pump is normally connected with the APU gearbox and the hydraulic pump can be disconnected from the APU gearbox for ground test and troubleshooting of the APU hydraulic pump;   a hydraulic pump cranking pad which allows a motor to drive the APU hydraulic pump when the APU hydraulic pump is disconnected from the APU gearbox for ground test and troubleshooting of the APU hydraulic pump and other hydraulic systems without running the APU in its entirety;   a turbine clutch which can be controlled to connect the APU hydraulic pump with or disconnect the APU hydraulic pump from a turbine, such that the APU hydraulic pump is normally disconnect from the turbine and
 when the APU hydraulic pump is disconnected from the APU gearbox, the APU hydraulic pump can be connected with the turbine for the turbine to drive the APU hydraulic pump to provide back-up hydraulic power in certain flight emergency cases and abnormal conditions and as a means to test and troubleshoot on the ground the APU hydraulic pump and other hydraulic systems without running the APU in its entirety; and 
 when the APU hydraulic pump is connected with the APU gearbox, the APU hydraulic pump can be connected with the turbine for the turbine to drive the APU through the APU hydraulic pump and APU gearbox as back-up starter on ground and in flight; and 
   a compressor clutch which can be controlled to connect the compressor with or disconnect the compressor from a turbine, such that the compressor is normally disconnected from the turbine and, regardless of whether the APU hydraulic pump is connected with the turbine or the APU gearbox, the compressor can be connected with the turbine for the turbine to drive the compressor to provide compressed air for air conditioning and anti-ice system in certain abnormal flight conditions and emergency cases and as a means to test and troubleshoot the air conditioning system on the ground without running the APU or the gas turbine engine entirely.