Gravity scavenged generator with integral engine oil tank

An auxiliary power unit for an aircraft comprising:

• a turbine internal combustion engine having a turbine main shaft and a forward bearing supporting the turbine shaft;
• a gearbox with gears connected to be driven by the turbine main shaft, the gearbox including a lower portion;
• an oil cooled generator including a rotor forward end, a rotor aft end, and a rotor shaft extending from the rotor aft end to the rotor forward end, the rotor shaft substantially parallel to the turbine main shaft, and connected to be driven by the gears, the oil cooled generator being mounted on the gearbox so that the gearbox is interposed between the generator and the engine, and said oil cooled generator having at least one generator oil gravity drain passage in flow communication with a lower portion thereof;
• an oil pump connected to deliver oil to the generator, to the forward bearing, and to the gearbox;
• an oil tank including a bottom wall and extending from a lower portion of said generator, the oil tank being in fluid communication with the oil pump and disposed to gravitationally scavenge the oil from said at least one generator oil gravity drain passage in said oil cooled generator;
• a gearbox oil gravity drain passage fluidly connecting the engine forward bearing and lower portion of the gearbox with the oil tank to gravitationally scavenge oil into the oil tank from the engine forward bearing and the gearbox;
• an oil tube adapted to carry oil from the oil tank to the oil pump;
• and
• a screen disposed in the oil tank, wherein the screen is disposed between an open top end of the oil tank and an inlet of the oil tube, wherein the oil tube passes through an aperture in the screen
• and wherein the rotor shaft is angled downwards towards the rotor forward end in relation to the oil tank bottom wall.