Pitot Heat

[Roger Long]

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.

--
Roger Long

[Gary Mishler]

"Roger Long" m> wrote in
message ...
> 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.

High performance aircraft will normally have Pitot Ht on at all times from
take-off to touch-down, visible moisture or not.

Some pitot tubes do have a venturi effect that can cause ice to build when
above freezing ambient temperatures.

If you don't have a [Pitot Heat] annunciator light that will alert you to a
break in continuity of your heating element, you can just check your amp
gauge to look for a current draw when you cycle the switch to confirm your
heat is working in flight. On pre-flight you can *momentarily* activate the
pitot heat and then *carefully* check that the probe is warm.

Regards,
Mish

[Icebound]

Gary Mishler wrote:
>
> ...snip...
> High performance aircraft will normally have Pitot Ht on at all times from
> take-off to touch-down, visible moisture or not.
>
> ...snip...

I assume one reason would be so that you keep the PT absolutely dry of
moisture so that it would not freeze when you climb above the Freezing
Level. Also I think you would be carrying a small amount of entrapped
air from the earth's surface (relatively warm and moist), which could
condense at the colder temperatures at altitude...

Does moisture alone screw up PT readings?

[David Megginson]

Icebound > writes:

> Does moisture alone screw up PT readings?

Part of the preflight checklist for my Warrior is to open up the pitot
and static drains beside the pilot seat to let out any moisture that
might have accumulated in the system, for what that's worth. I always
do it, and I've never seen any come out.


All the best,


David

[Scott Lowrey]

Roger Long 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?
>


I asked my flight instructor that today and he said that if you can't
see visible moisture, you don't need pitot heat. I guess I can go along
with that for low-performance aircraft but something tells me there's
more to it. (I did read the Haines column, so maybe that's what got me
thinking.)

What's the life expectancy of a pitot tube heater?

-Scott

[EDR]

In article >, David Megginson
> wrote:
> Part of the preflight checklist for my Warrior is to open up the pitot
> and static drains beside the pilot seat to let out any moisture that
> might have accumulated in the system, for what that's worth. I always
> do it, and I've never seen any come out.

Test question: What is the maximum engine rpm permitted to perform this?
(The Turbo Arrow IV manual provides a limitation)

[David Megginson]

EDR > writes:

>> Part of the preflight checklist for my Warrior is to open up the pitot
>> and static drains beside the pilot seat to let out any moisture that
>> might have accumulated in the system, for what that's worth. I always
>> do it, and I've never seen any come out.
>
> Test question: What is the maximum engine rpm permitted to perform this?
> (The Turbo Arrow IV manual provides a limitation)

I've never noticed a limitation, but then, I've never opened the
drains with the engine running.


All the best,


David

[Big John]

Icebound

On Sun, 02 Nov 2003 19:21:46 GMT, Icebound
> wrote:

----clip----

Does moisture alone screw up PT readings?

----clip----

When you fly through rain does your airspeed quit?

Big John

[Mike O'Malley]

"Roger Long" m> wrote in
message ...
> 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.
>

Personally, I've lost my pitot/static insturments when flying through moderate
to heavy rain without pitot heat on a 70 degree day. Of course, I didn't HAVE
pitot heat to turn on, but I got them back about an hour after I got out of the
rain.

I assume what happened was I got a few drops of water in the pitot tube and it
got plugged, and I had to wait for it to evaporate or blow out. I would guess
that if I had pitot heat on, it would evaporate the water quicker and possibly
have avoided the problem.

For the record, I was flying a PA-12 at about 40 mph indicated when it first got
plugged.

--
Mike O'Malley

[Jeff]

1000 or 1500 rpm ,have to check for sure, but that it the manifold pressure
release valve, and hold it for 5 seconds.


EDR wrote:

> Test question: What is the maximum engine rpm permitted to perform this?
> (The Turbo Arrow IV manual provides a limitation)

[Big John]

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"
m> 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.

[Robert Moore]

Big John > wrote

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

Not personally, but it was apparently a problem when I first
started airline flying (1967). Maintenence was constantly
complaining about flightcrews turning it on too soon before
takeoff or not turning it off quickly enough after landing.
After a couple of airline accidents related to pitot heat, a
switch was added to the squat switch to turn the heaters on
regardless of the cockpit switch positions.

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

I've had both pitots blocked on a B-720 (Belize Airways, 1978).
It was not obvious during preflight due to high location of the
pitot tubes and did not manifest itself until about 100kts by
which time it was time to fly. Pitch/Power solved the problem
easily.

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

Although technically correct (anything less than full IS partial),
"partial panel" in GA usually refers to loss of gyro instruments.
Pitch/Power would be a better way to describe flying without the
airspeed instrument.

Bob Moore

[Big John]

Bob

Smart move to tie to "Squat" switch in. I had my RO read the check
list to me every flight so never forgot to turn heat on and off.


On Tue, 04 Nov 2003 14:03:47 GMT, Robert Moore
> wrote:

>Big John > wrote
>
>> In my thousands of hours I have never experienced a pitot heater
>> failure. Have you BOb?
>
>Not personally, but it was apparently a problem when I first
>started airline flying (1967). Maintenence was constantly
>complaining about flightcrews turning it on too soon before
>takeoff or not turning it off quickly enough after landing.
>After a couple of airline accidents related to pitot heat, a
>switch was added to the squat switch to turn the heaters on
>regardless of the cockpit switch positions.
>
>> I've had insects get in pitot tube and block but that should be
>> caught on pre-flight.
>
>I've had both pitots blocked on a B-720 (Belize Airways, 1978).
>It was not obvious during preflight due to high location of the
>pitot tubes and did not manifest itself until about 100kts by
>which time it was time to fly. Pitch/Power solved the problem
>easily.
>
>> 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.
>> May have used some wrong words so anyone current on systems feel
>> free to take me to task.
>
>Although technically correct (anything less than full IS partial),
>"partial panel" in GA usually refers to loss of gyro instruments.
>Pitch/Power would be a better way to describe flying without the
>airspeed instrument.

I'll sure accept the terminology Pitch/Power. I just haven't heard it
used very much in GA so used the terminology that has been around for
years and years.

Oh Belize! Terminal used to be a couple of men in white shirts
sitting behind a rough hew'n (sp) table in a old palm limb Boheia
(sp). Used to fly the B/A-26 in there from Panama to 'show the flag.
The only bar in town was run by a German expiate (sp) (probably a
Nazi????) We always had to refuel and on every take off I had an
engine cut out :o( With the R-2800 (with water) cranking out 2500 HP
and the 'Lord' mounts cranked all one way and engine lost power
(quit), the cowling that set about 5 feet from cockpit, would rotate
about two feet with this loss of torque. Engine would then catch and
engine torque go up again and cowling would rotate back two feet. One
never knew if engine was going to stay on nacelle or come off???

Never found out why and even took a chamois one trip and ran all the
fuel through it and still cut out.

Was the road into town still built on a dike with dead trees an
alligators in the water along side?

Big John