Q: While TBO is recommended as 2,000 hours or 12 years, whichever comes first, the brokers trying to sell me a used plane always belittle that second limitation, chalking it up to Lycoming wanting to sell more rebuilds. Can you clear the air on this one?
HUTCHINSON PERSONS, via email
A: The text of Lycoming Service Instruction 1009AT, which addresses “Recommended Time Between Overhaul Periods,” has always been a controversial issue. While it lists the recommended hours for each engine, it also includes a rather profound caveat that has become a point of discussion by many: “All engines that do not accumulate the hourly period of time between overhauls specified in this publication are recommended to be overhauled in the 12th year.”
While it was generally thought to be a ploy by the engine manufacturers to sell more parts or factory overhauled or rebuilt engines, this was not the case.
Both Lycoming and Continental offer factory exchange engines as an alternative to a field overhauled engine at competitive prices. This has generated many engines being sold on an exchange basis, while providing both manufacturers with a realistic learning curve about their engines that have been in service under various conditions and times over a period of years.