View Full Version : engine life

memories of px
5th Apr 2019, 16:48
can someone please tell me the limitations for a flying school ( UK) aircraft please, is it 2200 then 10%, then must it be replaced with a new unit?
many thanks in advance

6th Apr 2019, 10:10
There isn't a fixed figure. Each engine type has its own TBO (to be overhauled). This may be different even for the same engine: if it is turbo charged, approved for aerobatics etc. Where an engine has an approved extension programme this figure is commonly 20%. In the case of a 2000 TBO engine it may therefore be extended "on condition" for a further 400 hours. If the engine is used wholly for private use the on condition programme can be without limitation of extensions.

6th Apr 2019, 16:34
Actually it's time before overhaul.

6th Apr 2019, 18:35
Remember the life is not just on hours, it is also on calendar,

As an example here is the Lycoming current engine life recommendations, some engines such as the 0-360 if used frequently as laid down get a greater number of hours over their normal TBO, see


The Uk then allows a variation to these hours and calendar as mentioned ( an extension of 20%) depending on certain criteria being met CAP 747 GR 24 refers, see page 346

private as said are on condition.


Kemble Pitts
6th Apr 2019, 19:45
I've always read it as Time Between Overhaul

6th Apr 2019, 21:29
Which is exactly what Lycoming use to describe it,see my first link above.

When the factory overhauls an engine it comes back with the total hours on the log book cert, so if it has been overhauled say twice and the engine has a TBO of 2000 the log book cert may have the engine hours listed since new, say 4,000 hrs, but will have been overhauled and will have 2000 hours to run, hence it is time between overhaul to the next one, if it was "before" then technically it would already be expired on hours in the legal sense under that description?

They do three types of engine, New, rebuilt overhauled to new dimensions and zero timed, and overhauled to overhaul specs that is a continuation of hours. ONLY the factories can zero time their engines.

7th Apr 2019, 08:14
I sit down corrected and I apologise.