The main purpose of lubrication is to reduce the friction between the moving surfaces and dissipate heat from the moving parts. It is also used as a substance to clean the interior of the engine and accumulate the deposits gathered along the way for removal. In a gas turbine engine, the largest and some of the most important moving parts are the ball and roller main bearings of the main driveshafts, which would also crucially require an oil supply. It is one of the most important parameters to monitor during engine start. If you don’t observe an increase in oil pressure the rotating parts of the engine will generate a lot of heat due to friction, eventually resulting in a fire. The oil pressure transmitter is usually located on the lubrication unit outlet line of the engine and oil pressure is indicated on a flight deck instrument.