OIL - DESCRIPTION AND OPERATION
1. General
A. The engine oil system is comprised of an oil storage and an oil distribution system together with
the necessary indicating systems which provide measurements of oil quantity, oil pressure, and
oil temperature. A low oil pressure warning system and filter bypass warning system are also
provided.
B. Each engine is provided with an independent oil system which provides cooling and lubrication
of engine gears and bearings. An oil storage tank, mounted on the lower left side of the engine,
furnishes a continuous supply of oil to the engine driven oil pressure pump in the accessory
drive gearbox housing. An external line carries oil from the pump to a full flow type fuel/oil
cooler. Cooled oil is then delivered to the engine bearings through a distribution manifold and
galleries formed in the engine structure.
C. An oil filter is provided downstream of the oil pump. The filter housing is made integral with the
accessory drive gearbox casing. A removable cover is located on the outside of the gearbox to
allow replacement or cleaning of the filter core. A bypass valve is arranged between the inlet
and outlet of the filter. If the filter becomes clogged, this valve will open and allow a flow of
unfiltered oil to circulate in the engine.
D. Oil is scavenged from the engine bearing cavities by pumps and returned to the accessory
drive gearbox. From there it is pumped back into the engine oil tank.
OIL - SERVICING
1. General
A. Servicing of the engine oil system is accomplished by either changing or replenishing the oil
supply. This procedure outlines the steps required to change the engine oil supply. Refer to
Chapter 12, Servicing for engine oil tank replenishment procedures.
2. Equipment and Materials
A. Engine oil conforming to PWA Specification 521B. (See PWA Service Bulletin No. 238.)
CAUTION: SOME OILS ARE NOT COMPATIBLE WHEN MIXED. UNLESS COMPATIBILITY
IS ASSURED, DO NOT MIX NAME BRAND OILS.
B. Six gallon container
C. One gallon container
CAUTION: ENSURE THAT SERVICING CONTAINERS AND OPENING ACCESSORIES
ARE CLEAN. DISPOSE OF UNUSED OIL REMAINING IN CONTAINERS.
3. Change Engine Oil
A. Open left side cowl panel.
B. Position containers to catch oil. Open oil tank drain on bottom of tank and remove main oil drain
plug from bottom of accessory drives gearbox housing.
NOTE: To facilitate draining oil from gearbox, remove plug and connector to drain oil from
standpipe cavity.
C. Remove nuts and washers securing main oil strainer cover to accessory drives gearbox.
Remove cover and main oil strainer element, discard two packings. Wash element in petroleum
solvent and inspect for metal particles. Refer to P&WA Chapter 72, Engine.
CAUTION: HOLD OIL STRAINER COVER TO KEEP IT FROM FLYING OFF UNDER
SPRING PRESSURE
D. Allow engine oil to drain to slow drip for approximately 1/2 hour. Install main oil drain plug and
standpipe cavity drain plug and connector in bottom of accessory drives gearbox housing.
Lockwire plugs.
E. Close oil tank drain valve on bottom of tank.
F. Install main oil strainer element in strainer port of accessory drives gearbox. Install strainer
cover and secure with washers and locknuts. Refer to P&WA Chapter 72, Engine.
CAUTION: BE SURE STRAINER ELEMENT IS INSTALLED RIGHT SIDE UP. WHEN
CORRECTLY INSTALLED, THE STRAINER BYPASS VALVE WILL BE AT THE
COVER END OF THE ELEMENT.
G. Remove self-locking filler cap from port in sump cavity and fill oil tank to center of upper sight
gage with new oil. Replace oil tank filler cap and install, or close, cowl panels.
CAUTION: INSECURE INSTALLATION OF THE OIL TANK FILLER CAP MAY OCCUR IF
INTERNAL STOPS ARE WORN PERMITTING INCORRECT LOCK ROTATION.
CHECK FOR PROPER LUG ENGAGEMENT AFTER CAP IS INSTALLED AND
LOCK HANDLE IS TURNED TO "CLOSE" BY ATTEMPTING TO REMOVE CAP.
(PULL STRAIGHT OUT ON HANDLE BY HAND OR WITH A WIRE HOOK AS
SHOWN IN FIGURE 301.) WHEN STOWING LOCK HANDLE, CHECK THAT
MACHINED SURFACE OF HANDLE IS TURNED UP AND AS-CAST SURFACE
IS DOWN TOWARD CAP. PROPERLY LOCKED AND STOWED, THE LOCK
HANDLE PRESENTS A SMOOTH FLAT SURFACE THAT IS FLUSH WITH THE
CAP.
NOTE: If the engine oil supply was changed from one type of oil to another, operate engine at
idle rpm for at least 1 minute. After engine shutdown, drain and service the system per
steps A, B, D, E, and G.
When the engine is operated for the first time after an oil change, check the oil supply
tank level after engine shutdown and replenish as required. Refer to Chapter 12,
Servicing.
ENGINE OIL STORAGE - DESCRIPTION AND OPERATION
1. General
A. Each engine is provided with a cylindrically shaped oil tank which mounts on the left front face
of the accessory drive gearbox and is secured at the front by a strap. With the engines installed
on the airplane, the tank holds approximately five U.S. gallons. The remaining tank volume
accommodates foaming and expansion of the oil.
2. Engine Oil Tank
A. The tank is constructed of stainless steel and is capable of withstanding without permanent
deformation, the stresses imposed by pressure, vibration, and shock loads such as can occur
during landing, rough flight conditions, etc. A baffle serves to minimize sloshing of the oil in the
tank. A deaerator in the tank separates most of the air from the returning oil, thus minimizing
foaming.
B. Servicing of the oil tank is accomplished through a filler port, located in a sump cavity. When
servicing through the filler port, any oil that is spilled in the sump cavity is drained through
tubing to drain holes in the cowl panels.
C. For ground check of oil quantity, a dipstick is attached to the self-locking filler cap. A
capacitance sensing probe in the tank transmits an electrical signal for remote indication of oil
quantity during flight.
D. The tank is equipped with an inlet strainer at the filler port. An outlet strainer is located at the
drain valve on the underside of the tank.
3. Oil Tank Drain Valve
A. The oil tank drain valve is located at the bottom of the oil tank. The handle is spring-loaded to
the valve closed position. Manually rotating the handle 90 degrees in a clockwise direction
opens the valve allowing the oil to drain from the tank. The handle is locked in the valve open
position by a ball detent arrangement. Counterclockwise movement of the handle unseats the
balls form the detents and allows the spring tension to return the handle to the valve closed
position. (See figure 1).
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