On Sat, 16 Oct 2004 08:11:18 +0100, Peter wrote:

The FAR book suggests

Flight time means:
(1) Pilot time that commences when an aircraft moves under
its own power for the purpose of flight and ends when the
aircraft comes to rest after landing

that maintenance should be based on total time in motion, and I
wondered how many people do that. It would increase hours-based
maintenance costs (e.g. the engine fund) by 15-25% depending on how
much time one typically spends on the ground.

The FAR's do NOT define maintenance time that way. The FAR's rather use
the phrase "time in service" and FAR 1.1 defines TIS as

"Time in service", with respect to maintenance time records, means the time
from the moment an aircraft leaves the surface of the earth until it
touches it at the next point of landing.

That would be less than flight time, which is defined (also in FAR 1.1) as:

Flight time means:
(1) Pilot time that commences when an aircraft moves under its own
power for the purpose of flight and ends when the aircraft comes to rest
after landing.

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Tach time in most a/c is probably close enough to TIS to be useable as
such, and has been how the records are kept at every maintenance shop I've
been at (in the US) over the past 30 or so years of a/c ownership.

Now with GPS becoming more prevalent, and with GPS having the ability to
start/stop a timer based on a/c speed; or by using a timer tied to a squat
switch or similar; I suppose one could keep times based on actual TIS as it
is defined in the FAR's.

--------------------------

However, I believe Part 91 only mentions maintenance time with regard to
determining when a 100 hr inspection is due. Part 43 does indicate that
"time in service" is what is supposed to be recorded when maintenance is
performed.



Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)