Maintenance of gas turbine lubrication systems consists mainly of adjusting, removing, cleaning, and replacing various components. Oil filter maintenance and oil change intervals for turbine engines vary widely from model to model, depending on the severity of the oil temperature conditions imposed by the specific airframe installation and engine configuration. The applicable manufacturer’s instructions should be followed. The oil filter should be removed at every regular inspection. It should be disassembled, cleaned, and any worn or damaged filter elements replaced. The following steps illustrate typical oil filter removal cleaning and replacement procedures:
- Provide a suitable container for collecting the drained oil, if needed.
- Remove the filter housing and withdraw the filter assembly. [Figure 6-48] Discard the old seals.
- Immerse the screen or filter in an approved carbon remover at room temperature for a few minutes. Rinse them in a degreaser fluid or cleaning solvent. Then, blow them dry with an air jet.
- Then, install the filter in the filter housing assembly. Place a new seal and tightened to the torque prescribed in the manufacturer’s instructions.
- Secure with lock wire.
To adjust the oil pressure, first remove the adjusting screw acorn cap on the oil pressure relief valve. Then, loosen the locknut and turn the adjusting screw clockwise to increase, or counterclockwise to decrease, the oil pressure. In a typical turbojet lubrication system, the adjusting screw is adjusted to provide an oil pressure of 45, ±5 psi, at approximately 75 percent of normal rated thrust. The adjustment should be made while the engine is idling; it may be necessary to perform several adjustments before the desired pressure is obtained. When the proper pressure setting is achieved, tighten the adjusting screw locknut, and install the acorn cap with a new gasket, then tighten and secure with lock wire.
Maintenance of scavenge and breather systems at regular inspections includes checks for oil leaks and security of mounting of system components. Also, check chip detectors for particles of ferrous material and clean last-chance filters; install and safety.