3. Oil filter and condition monitoring system
At this location it flows through the scroll vanes
4. Oil coolers
that function as an air/oil cooler. This further
cools the oil and heats the vanes for full-time anti-
5. Chip detector
icing. The vanes discharge oil into the oil tank.
Oil Tank
If the oil cooler pressure becomes too high, a relief
valve will open to dump scavenge oil directly into
The oil tank and air/oil cooler are integral
the oil tank.
parts of an aluminum casting. Tank capacity is
7.6 U.S. quarts. The filler port is on the right side
Engine Chip Detector
of the engine, and the filler design make it
impossible to overservice the tank. Oil flows to
The chip detector is on the forward side of the
the oil pump through a screen. The oil level is
accessory gearbox. It consists of a housing with
shown by a sight gauge on each side of the tank.
an integral magnet and electrical connector, with
The scavenge pump returns oil from the sumps
a removable screen surrounding the magnet. If
and accessory gearbox to the oil tank through six
there are chips, the completed circuit illuminates
scavenge screens.
the appropriate number engine CHIP light.
Oil Pressure System
MAINTENANCE
Oil suctioned through the pressure element of
the pump is pressurized and flows through the oil
filter. The oil then flows into passages in the
Maintenance of the oil system is an item of
accessory gearbox and to the six main bearings
major importance to the Aviation Machinist's
in the sumps. A cold-start relief valve downstream
Mate. It consists mainly of adjusting, removing,
of the filter protects the system by dumping any
cleaning, and replacing various parts. To
extra oil into the accessory gearbox case. Air jets
troubleshoot and repair oil systems effectively,
blow across the oil jets to provide continuous oil-
you should be thoroughly familiar with both the
mist lubrication. The engine has two sets of oil
external and internal oil systems.
jets to provide each main bearing with oil for
cooling and lubrication. Scavenge to the scavenge
LOCATION OF LEAKS AND DEFECTS
elements of the pump flows through screens at
the pump inlet, and then through the electrical
The immediate location of any leak or defect
chip detector. The oil then flows through the oil
within the oil system of any aircraft engine is
cooler, main frame, scroll vanes, and into the oil
important. The life of the engine is in its oil
tank. If the oil pressure drops below 24 psi, the
supply. Whenever a leak develops or the oil flow
appropriate ENGINE OIL PRESS caution light
is restricted, a part failure or loss of the engine
lights in the cockpit.
may result.
Locating leaks in the external oil system is
Oil Filter
easy. Often a visual inspection shows a loose line
or leaking gasket. Although, you should never
Oil discharged from the oil pump is routed to
assume that an obvious corrective action is all that
a disposable element. The element is a 3-micron
is needed.
filter located on the forward, left-hand side of the
AGB. As the pressure differential across the filter
REPLACEMENT OF GASKETS,
increases, the first indication will be a popped
impending bypass button. As the pressure in-
SEALS, AND PACKINGS
creases, the OIL FLTR BYPASS caution light will
illuminate at the same time the filter bypass
A large portion of the maintenance involved
is the replacement of parts and repair of various
occurs.
oil leaks. Much of this maintenance requires the
use of new gaskets, seals, and packings.
Oil Coolers
New seals are packaged to prevent damage.
These packages are identified from technical
Scavenge oil is cooled before it returns to the
information printed on the package. This
tank by a fuel/oil cooler. After passing through
information identifies the use and qualifications
the oil cooler, oil enters the top of the main frame.
5-17
