located in the highest point of the oil tank, prevents flooding of the accessory gearbox if the oil tank is
overfilled. A drain plug is mounted in the bottom of the tank.
A gear-type oil pressure pump is located in the lowest part of the tank. The pump
consists of two gears contained in a cast housing, bolted to the front face of the accessory diaphragm. It
is driven by the accessory gearshaft which drives the internal double-element scavenge pump. The oil
pump has an inlet filter screen, check valve, and relief valve.
The oil filter assembly consists of a disposable cartridge type filter element with a
perforated flanged end, bypass valve, and check valve. The filter assembly housing is located in the
compressor inlet case at the 3 o'clock position. If the filter becomes clogged, the increased pressure
opens the bypass valve, and an alternate passage for unfiltered oil to flow through the engine is used.
The check valve, positioned in the end of the housing, prevents gravity flow into the engine after
shutdown and permits the filter element to be changed without having to drain the oil tank.
The centrifugal breather consists of a shrouded aluminum alloy impeller secured to the
rear face of the starter-generator gearshaft by a retaining ring. Breather air flows radially inward through
the rotating impeller housing where the oil particles are separated from the air mist by centrifugal force.
The oil particles are thrown outward and drain freely to the bottom of the accessory gearbox. The air is
then routed through a transfer tube to a breather boss on the rear face of the accessory housing where a
connection for an overboard vent line is installed.
The oil-to-fuel heater assembly is essentially a heat exchanger which uses heat from the
engine oil lubricating system to preheat the fuel in the engine fuel system. The heater has a
Vermatherm element, which senses fuel temperature, and consists of a highly expansive material sealed
in a metallic chamber. The expansion force is transmitted through a diaphragm and plug to a piston.
The element senses outlet fuel temperatures and, at temperatures above 70 F, starts to close the core
valve and simultaneously opens the bypass valve. At 90 F, the core valve is completely closed and the
oil bypasses the heater core.
PRESSURE AND SCAVENGE OIL SYSTEMS
Oil for lubrication of engine parts is supplied under pressure by the pressure oil system. This
oil is then returned to the oil tank