Piston engine calendar time under FARs
Under the EASA regime in Europe, engines used for commercial use, which includes flight training, have to be overhauled either on TBO or calendar time, e.g 12 years for some Lycoming engines. This ruling is inflating the cost of training aircraft in Europe and causing difficulties for flight schools. I cannot see the same regulation exists under the FARs, only the TBO requirement. Can any of our American friends confirm whether calendar time is part of the regulation for airworthiness, including for flight training?