While it has no moving parts, they due "burn out" by overheating. Its a
cigarette
lighter, the filiment can and does burn out, usually caused by overheating.

Also, smaller GA singles will notice the current drain on the system
(espicially if
they have not beefed up the alternator and have a brand new radio stack with
high
powered radios, cd players, etc... ).

I was actually working on a temperature switch setup, one that would allow
you to turn
the switch on all the time, yet would not actually power it if the
temperature was above
say 5C or so. This would significanly help with the burn out, but not the
current draw issue.

Scott

"Mike Rapoport" wrote in message
hlink.net...
Leave it on all the time. Every checklist for a turbine airplane that I
have seen says to turn it on. All airlines leave it on all the time.
Since
the heat is just a resistance element with no moving parts, I doubt that
it
will "wear out faster" as others have suggested. Mine have 4600hrs on
them
and presumably they have been on all that time.

Mike
MU-2


"K. Ari Krupnikov" wrote in message
...
Coming back from Mammoth this past Sunday and flying through a snow
cloud West of the Sierras, I had the Pitot freeze over. I realized it
was frozen when I tried to correct for altitude gained in turbulence
and the airspeed indication didn't increase even as I pushed the nose
down and could hear the relative wind increase. Not a big problem -- I
could see where I was going on the AI, and a minute or less after I
turned Pitot heat on, ASI returned to normal.

This did raise a question -- is there a good reason Pitot heat isn't
on all the time? It doesn't seem to be a big power drain, and unlike
carb heat does not to my knowledge affect performance. Is there a
reason I shouldn't turn it on when I put transponder on ALT and turn
it off when I shut down electrics before engine shutdown?

Ari.

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