By now, I suspect most AVweb readers know that I am a strong advocate of overhauling piston aircraft engines "on condition" rather than "on time." I have always considered it both irrational and uneconomical to tear down an otherwise healthy engine just because it has attained some arbitrary number of hours or years in service.In my Savvy Owner Seminars, I teach my aircraft-owner students to monitor the health of their engine using all the available tools -- oil-filter inspection, oil analysis, monitoring oil-consumption and oil-pressure trends, compression tests, borescope inspections, spark-plug inspections, and digital engine-monitor data -- and to overhaul their engines only when the engine says that it's time.I practice what I preach. The engines on my Cessna T310R are both now at 750 hours past TBO (time between overhauls), and running so well that it would be a capital offense to tear them down. I monitor their condition very carefully, and have no plans to overhaul them any time soon.It's perfectly legal for owners of Part 91 aircraft to operate engines past the engine manufacturer's recommended TBO. Commercial operators under Part 135 often press on beyond TBO as well, although they need to ask permission to do so from their FSDO principal maintenance inspector (and such permission is routinely granted).Nevertheless, many aircraft owners and mechanics remain uncomfortable with the idea of operating beyond recommended TBO. There is a widespread belief that such "TBO busting" is unwise because it increases the risk of engine failure.
This is a companion discussion topic for the original entry at https://www.avweb.com/ownership/the-savvy-aviator-45-how-risky-is-going-past-tbo