To prevent unwanted friction, polish the surface.

Oil distribution is that portion of the system which is used to conduct oil from and to the engine.

For turbine engines, exhaust includes units external to the basic engine.

Thrust reverser is used to change the direction of the exhaust gases for reverse thrust.

Noise suppressor is that portion of the system which reduces the noise generated by the exhaust gases.

Exhaust are those units and components which direct the engine exhaust gases overboard.

It includes items such as ignition harness, high tension leads, coils as used in "low tension" systems, spark plugs, igniters, etc.

It includes wiring between magneto and distributor in those systems where they are separate units.

That portion of the system is used to conduct high or low voltage electricity from the electrical power supply to the spark plugs, or igniters.

It includes items such as magnetos, distributors, booster coils, exciters, transformers, storage capacitors and compositors, etc.

That portion of the system is used to generate electrical current for the purpose of igniting the fuel mixture in the combustion chargers and thrust augmentors.