ENGINE LUBRICATION SYSTEM
With components rotating at speeds of over 37,500 RPM, the engine
lubrication system is vital to proper engine operation. The lubrication system
consists of a pressure system, scavenge system and a breather system. The
main components of the lubrication system include:
• An integral oil tank at the rear of the engine.
• An oil pressure pump at the bottom of the oil tank.
• An external double-element scavenge pump located on the back of the
accessory gearbox.
• An internal double-element scavenge pump located inside the
accessory gearbox.
• An oil-to-fuel heater located on the upper portion of the accessory
gearbox.
• An oil lter located on the right side of the oil tank.
• A large-capacity oil cooler mounted on the left side of the engine.
Pressure Oil System
Oil is drawn from the bottom of the oil tank through a lter screen, where it
passes through a pressure relief valve for oil pressure regulation. Pressure
oil is delivered from the main oil pump to the oil lter where foreign matter is
removed from the oil, precluding further circulation. Oil then exits the oil lter
outlet and divides into several paths.
Lubrication of the accessory drives and bearings is accomplished through
cored passages in the compressor inlet case, accessory diaphragm, and
gearbox housing and into the gearbox bearing areas. The No. 1 bearing is
lubricated by pressure oil from the lter outlet through a cored passage in
the compressor inlet case, to a nozzle at the center-bore and to the rear of
the compressor rear hub. The nozzle, containing a ne strainer, directs the
calibrated oil ow into a collector ring mounted on the rear of the compressor
rear hub, and through passages in the split inner race to the bearing. A cored
passage at the main oil lter outlet conducts a portion of the pressure oil to
a minimum pressurizing valve installed in the compressor inlet case at the 2
o’clock position. Oil is then applied to the oil-to-fuel heater where, depending
upon temperature of the fuel, the oil is utilized to preheat the fuel. Oil from
the heater is returned to the oil tank via a check valve and adapter at the 12
o’clock position on the compressor inlet case.
A common supply is provided to lubricate the No. 2 bearing, the reduction
gearbox and front accessories, power turbine No. 3 and 4 bearings, and the
propeller installation. Oil from the lter outlet is directed through a cored
passage and transfer tube to an outlet boss at the 4 o’clock position on the
compressor inlet case. An external oil transfer tube connected to the boss
directs the oil forward to a tee coupling at the gas generator case. An internal
oil transfer tube directs the oil to an oil transfer gallery in the No. 2 bearing
compartment. The gallery houses two nozzles which are protected by a ne
strainer. The nozzles direct the oil ow onto the front and rear faces of the
bearing. A second external oil transfer tube directs the oil forward from the
tee coupling on the gas generator case to a boss on the front case of the
reduction gearbox.
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