My guess would be: Not unless they are carriers (passengers), not merely
commercial operators per se. Note he says even air carriers have gotten
waivers up to half again the TBO time. I recall that one of Deakin's
articles stated that in the great long ago, the airlines were running the
radial engines to DOUBLE their normal TBO time (though we can be certain
that the rules have changed even now in the turbine era).

The interesting part of the article, though, is his point that you can be
wayyyyy below TBO and not be AIRWORTHY. Also, that the most likely time for
engine failure is right _after_ TBO, not _ just before_.

As for flight schools:

Sec. 141.39 Aircraft.

An applicant for a pilot school certificate or provisional pilot
school certificate must show that each aircraft used by that school for
flight training and solo flights meets the following requirements:
(a) Each aircraft must be registered as a civil aircraft in the
United States;
(b) Each aircraft must be certificated with a standard airworthiness
certificate or a primary airworthiness certificate, unless the
Administrator determines that due to the nature of the approved course,
an aircraft not having a standard airworthiness certificate or primary
airworthiness certificate may be used;
(c) Each aircraft must be maintained and inspected in accordance
with the requirements under subpart E of part 91 of this chapter that
apply to aircraft operated for hire;

141.91 (???) pertains to Satellite Operations: what the hell are those?)



I agree and have also previously read Mike Busch's article but question
really is whether renting an airplane and providing a flight instructor is
a
commercial operation, one without Op Specs., where, presumably, the most
conservative interpretation would be applied. Do flight schools generally
have to overhaul at TBO?

Mike
MU-2



"Matt Barrow" wrote in message
...

wrote in message
news:r5dNe.22116$Rp5.7682@trnddc03...

On 18-Aug-2005, "Doug" wrote:

I am quite sure that one can offer an aircraft for hire with an
instructor under part 91 with an engine that has gone beyond TBO.


My understanding of the "official" FAA interpretation is as follows:
Renting an airplane, as opposed to chartering one, does not constitute
a
commercial, "for hire" use. Hiring of a flight instructor is a
separate
transaction not tied to the rental of the airplane. Therefore,
regulations
specifically governing commercial operations do not apply to airplanes
that
are rented out for instruction or for general use by pilots, regardless
of
whether dual instruction is given. Of course, if the pilot renting the
airplane is going to use it for commercial purposes then the plane must
meet
commercial use maintenance and operational regulations.

Because this interpretation is contrary to widely held belief it is not
surprising that a local FSDO would provide a different reading.

-------------------------------------
http://www.avweb.com/news/columns/187037-1.html

The Savvy Aviator #4: Debunking TBO

Engine TBO (time between overhauls) seems to be one of the most
misunderstood concepts in aviation maintenance. There are lots of
TBO-related old wives tales that are widely believed by owners and
mechanic
alike, and they can cost owners a great deal of money. Mike Busch
endeavors
to clear up these misconceptions, and explain what TBO really means.
By Mike Busch




(MYTH) "While it's true that manufacturer's TBO isn't compulsory for
non-commercial (Part 91) operators, commercial (Part 121/135) operators
are
required to overhaul an engine when it reaches TBO."

Not so. Both Lycoming and TCM publish engine TBOs in the form of
non-mandatory service bulletins. Some Part 121/135 operators have
Operations
Specifications that require them to comply with all manufacturer's
service
bulletins (even non-mandatory ones), while others have Op Specs that
require
compliance only with mandatory service bulletins. Those in the latter
group
are no more obligated to comply with published TBO than are Part 91
operators. Those in the former group might theoretically be required to
overhaul at published TBO, but most such operators request TBO
extensions
from their FSDO and these are routinely granted, often for as much as
50%
over the engine manufacturer's published TBO. So, in actual practice,
published TBO is hardly ever compulsory for any operators -- commercial
or
non-commercial.