Spray jet lubrication is used on all compressor, gas producer turbine, and power turbine rotor
bearings, and to bearings and gear meshes of the power turbine gear train, with the exception of the
power output shaft bearings. The power output shaft bearings and all other gears and bearings are
lubricated by oil mist.
A spur-gear oil pump assembly, illustrated in figure 7.10, consisting of one pressure element
and four scavenge elements, is mounted within the accessory gearbox.
Figure 7.10. Oil Pump.
The oil filter assembly, located in the upper right-hand side of the accessory gearbox, consists
of a filter bypass valve and a pressure regulating valve. Oil from the tank is delivered to the pressure
pump which pumps oil through the filter and then to the points of lubrication. The oil pressure is
regulated 115-130 psi by the pressure regulating valve.
The engine lubrication system incorporates four screens, two magnetic chip detector plugs,
and two check valves. The check valve in the oil filter outlet passage prevents oil in the tank from
draining into the engine when it is not in operation.