What is the life of a Jet Engine??

[The man formerly known as]

In Piston planes the engine is lifed at usually 2000 hours with on condition extensions and the option to zero time the engine.

Does the same apply to Jet engines fitted to transport aircraft. Are they lifed or just checked until something goes below tolerance.

How many hours can you expect from an engine fitted to the 747 or the 777 for example.

[Pilot Pete]

TMFKA

Take a look at this <a href="http://www.rolls-royce.com/civil/products/turbofans/rb211-535/Default.htm" target="_blank">http://www.rolls-royce.com/civil/products/turbofans/rb211-535/Default.htm</a> which is about the RB211-535 'the worlds most reliable turbo fan'. Note one of them did more than 40,000hrs on the wing!


PP

[ft]

There can be limits on calender time, cycles, running time, flight time etc but the trend is to go more and more towards on-condition maintenance. With maintenance diagnostic computers, vibration measuring, FADECs, more parameters in DFDRs etc it is often safer to maintain on condition - every time you tear down an engine, there's a chance of introducing a fault.

Cheers,
/ft

[Roadtrip]

Depends on how they're treated. Commercial engines that are subjected to lots of max power takeoffs won't last as long (like freighters). Reduced thrust takeoff really save wear on engines. Also, commercial engines operate more or less at a steady thrust setting. Military engines, expecially on combat aircraft, are subjected to a lot more abuse through throttle bursting, lots of thrust changes and use of high power more often. Military engines are usually overhauled about every 4000 hours, vice maybe 20,000+ for commercial engines.