Sukhoi, MiG and others have been pushing the engine companies to to improve
the
engine TBOs, so that western and western-oriented airforces will be more
willing to
buy them. Many of the joint venture commercial transports have been offered
with
western engines, for the same reason. They've still got a ways to go, as
ISTR the
F100 has a TBO of 4,000 hours now, and IIRC the most modern engines are
intended to
have only on-condition maintenance between overhauls, but I'll leave it to
others
with more knowledge and experience to confirm or deny that.

Guy





Sounds about right for the turbine. At 2.0 - 2.5 thermal cycles per operating
hour, 4000 hours is about 8,000 - 10,000 cycles. The compressor and fan run
quite a bit longer, hence the modular maintenance approach. When one module
reaches its limit it iw replaced, not the entire engine. There are also
intermediate inspections up until the end of the life cycle, but those are
mostly for inspection, not replacement except for certain parts like shrouds
and combustors.

Pretty much the same aproach to maintenance in high bypass fans in the heavies,
too though they accumulate thermal cycles more slowly, something around 1.0 or
less because of far fewer throttle transients.

Different approach for engines like the TF33 in the B-52 and C-141 because
those are not mudular engines. The entire engine has a TBO on them, but in
those application it is almost more of a fly to failure.