TM 9-6115-664-13&P
1-23. ENGINE LUBRICATION.
a.
Engine lubrication is controlled by a crankshaft driven oil pump. The oil pump is housed in the engine
crankcase (1, Figure 1-10) and supplies all oil to lubricate and cool high friction internal components. The crankcase acts
as the oil sump, since a separate oil pan does not exist. The oil pump draws oil from the oil sump and passes it through
an oil filter element (2). After the oil passes through the element it is pumped through the engine oil cooler
(13, Figure 1-7) and then to oil jackets to lubricate the crankshaft and camshaft bearings.
b.
An oil pressure valve (3, Figure 1-10) relieves high pressure into the oil sump to prevent excessive build up of
oil pressure in the lubrication system. An oil pressure switch (4) (normally open) protects the engine from sudden loss of
oil pressure. Should pressure drop below the minimum required for safe operation, the oil pressure switch will close,
cutting electrical power to the engine run/stop solenoid. Once oil pressure returns to normal, the oil pressure switch will
open. Engine oil level is monitored using an engine oil level dipstick (5). The engine is serviced at the engine oil filler port
(6). An engine drain valve and hose assembly (7) allows the engine oil to be drained to a pan outside the APU enclosure.
1. Crankcase
2. Oil Filter Element
3. Oil Pressure Valve
4. Oil Pressure Switch
5. Oil Level Dipstick
6. Oil Filler
7. Oil Drain Valve and Hose
Figure 1-10. Engine Oil System
1-22
