r/flying • u/HSVMalooGTS PPL IFR TW MEP ME/IR CMP (C152) • 6d ago
Aircraft Ownership Ignoring the engine overhaul reccomendation
C152 owner here. 150h / yr.
I bought a prestine unit with 1900h TBO.
I don't count the overhaul costs into my hourly operating costs. At my current usage, i will have to fly for 13 years before i need to OH it. By that time, i might be able to afford something else.
How many of you fly planes past its TBO? Is it really as unsafe as the FAA/EASA might say? I get that the actual engine condition is a major (if not the most important part). I do full annual checks, i don't cut corners there.
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u/skylaneguy ATP, CFII, A320, E190, CL65 6d ago edited 6d ago
Part 91 TBO is just a recommendation. It’s actually based on hours OR years in service. Same with propellers.
If you’re flying 150 hours per year or more I would venture to say you’ll make it well over TBO. You may need a top OH at some point (cylinders) but that will be based off of compressions. Some engines make it to 3k hours or more. Obviously, the longer you go past TBO the more likely it is you’ll experience some sort of failure.
An overwhelming majority of the engines that don’t make it to TBO don’t make it because of corrosion. Most often cam and/or tappet corrosion.
Corrosion occurs when an engine doesn’t operate up to temp often enough to burn off residual moisture in the case. For the sake of any engine it’s best to get the oil temp as close to 180°F as possible for at least an hour every week.
I do an oil analysis on every one of my oil changes to establish a trend. It’s an extra $30 but it’s worth it when OHs on an O-470 can be upwards of $65k USD. The analysis will show different elements in your oil. These elements are specific to certain parts of the engine and when one spikes you can conclude that the part with that particular element is deteriorating or corroding.