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Lycoming TBO (time before overhaul)

    TBO is the set time (established by manufacturer) that the component or part is required to be overhauled.  In other words, a typical normally aspirated Lycoming engine (non-turbocharged) typically has 2000 hours of operation until it needs to be overhauled.  The owner is not required overhaul the engine, but the engine needs to be removed from service.  There are many considerations Lycoming uses to establish the TBO times and they include rotation speed, operating pressures, materials of construction, operational history and other considerations.  The TBO also changes for the aircraft the engine is installed including: rotary wing (helicopters and others), aerobatic, utility, others.  The most recent TBO information for Lycoming opposed piston engines can be found in Service Instruction No. 1014M.  Find the link listed below.  There are other considerations regarding TBO including the possibility that the engine may never reach TBO.  Calendar time is just as important as TBO.  Lycoming recommends that the engines "be overhauled in the twelfth year".  Some engines last 20-25 years in the less corrosive environments.  Unless the engine has had a teardown inspection or cam replacement since the last overhaul, there is no sense in going past 20-25 years of accrued calendar time.  

Links

Service Instruction No. 1014M  

Notes:

Service instruction 1136A is an old service instruction from 1967.  If the engine still has 7/16 exhaust valve stems, it needs to be replaced.

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Last modified: February 24, 2007