Roger

The pitot heater when bird is flying is cooled by the airflow and
doesn't get super hot which could cause a failure in a short period of
time.

In my thousands of hours I have never experienced a pitot heater
failure. Have you BOb?

Flying All Weather Interceptors we did check heater on preflight.

You can do same in GA if visable moisture is seen or forcast..

I've had insects get in pitot tube and block but that should be caught
on pre-flight.

If it (heater) were to fail and the pitot tube ice up and become
blocked then you can fly partial panel until you can get to an
altitude where the ice will melt. In fact you can land partial panel
if you have any experience partial panel.

The pitot system is a 'closed' system and anything entering the pitot
tube will not migrate back to the airspeed indicator.

The 'L' shaped pitot tubes have a small calibarated hole as I recall
in the bottom just as they bend up and go insuide the wing/fuselage
and any water that gets in the front of the tube is drained out by ram
air pressure and gravity.

May have used some wrong words so anyone current on systems feel free
to take me to task.

Bottom line is that moisture in pilot tube is not a real big problem
in my estimaton, Visable moisture, just turn on the pitot tube and go
fly.


Big John


On Sun, 02 Nov 2003 16:43:54 GMT, "Roger Long"
om wrote:

Did I miss this in my training?

I thought Pitot Heat was only needed in icing conditions. Tom Haines column
in this months AOPA mag recommends turning it on in or near moisture at any
temperature. Is this a typical recommendation?

Is there an effect like a carburetor that could cause ice to from in the
pitot at above freezing ambient temperatures?

Since the heat is provided by a hot filament, having it on a lot
unnecessarily would make me worry about finding that it's not there when you
need it.