Figure 3-2. Engine Oil System

CHAPTER THREE

T-34C AIRCRAFT SYSTEMS FAMILIARIZATION

WORKBOOK

Figure 3-2 Engine Oil System

The main oil tank is an integral part of the engine casing. It is located in the area between the

accessory gearbox and compressor inlet casing. The system includes an auxiliary oil tank, which

is attached to the bottom of the accessory gearbox and contains one quart of oil, necessary for

inverted flight. The oil system capacity is 4.4 U.S. gallons. The oil tank filler neck is located on

the accessory gearbox. The oil filler cap is a yellow locking type cap in which the tab on top

must be in the down position to lock the cap for flight. A dipstick is attached to the filler cap and

indicates the "acceptable for flight" oil quantity between a minimum and maximum mark in

either the hot or cold range. (Note: dipstick graduated in quarts.)

The oil to fuel heater assembly, located on the accessory gearbox, is essentially a heat exchanger

which uses heat from the engine oil system to preheat the fuel prior to its entering the primary

fuel pump. The fuel temperature is maintained between 70 and 90 degrees Fahrenheit.

The main oil pump (known in NATOPS as the oil pressure pump) is located in the lower part of

the main oil tank and is used to supply oil under pressure to engine components. It is a gear type

pump driven by a shaft from the accessory gearbox. Oil enters the pump through a pipe with a

two-way inlet valve. This valve has a pickup tube at the top and bottom of the tank to ensure an

oil supply during normal and inverted operations.

There are two dual-element, gear type scavenge pumps; one is located inside the accessory

gearbox, and the other mounted externally on the accessory gearbox. They both return oil

through the oil cooler to the main oil tank. The internal scavenge pump is driven by the same

3-4 PT6A-25 AIR/OIL/IGNITION SYSTEMS