Limiting Factors of OVERHAUL PERIODS for AIRCRAFT ENGINES

FOR the purposes of this discussion, a hypothetical engine was adopted which is intended to possess operating characteristics representative of all of the types and models of engines currently being operated by the domestic airlines.

The desirable or optimum overhaul period is described as being that interval during which the engine can be operated with maximum economy and without sacrificing the reliability of any other overhaul period.

A brief description is given of the various groups of engine parts and a typical overhaul inspection of the pertinent parts is described. It is concluded that the limiting factor for engine overhaul periods is the accumulation of the centrifuged deposit in the crankpin which limits the overhaul period to approximately 1000 hr. It is further concluded that this condition can be alleviated by the provision of effective filtering facilities in the lubrication system and by improved scavenging of the lead products of combustion.