Cherokee 180 dash heating problem

Hey Cherokee owners,

Has anyone run into a problem with the whole dash and all avionics
heating up???

Since I bought the plane this past summer, I thought all the heat
build up was due to our famous San Antonio summer weather. But I flew
into a cold front last night and the temp went down below 40F. Even
with it that cold -- the dash got uncomfortably hot after an hour and
a half flying.

The dash all around the center radio mounts, the radios themselves,
and the avionics stack in front of the co seat were so hot that it was
uncomfortable to put your fingers on it for more than a couple
seconds. I was under the hood at the time, so didn't take the time to
check the whole dash and didn't think to check on the pilot's side.
But the dash on the left side of the radio stack in the center was hot
too.

Has anyone run into this before? I've already checked the exhaust and
shrouds -- all OK. I'm going to spend some floor diving tomorrow to
make sure the heat and defrost vents behind the dash haven't come
loose. But they were OK a month ago when I was back there.

Thanks for any suggestions you guys can provide.


Chuck

Chuck wrote:
: Hey Cherokee owners,

: Has anyone run into a problem with the whole dash and all avionics
: heating up???

If your Cherokee is new enough to have the wing root air intakes, there is a
little 1" scat tube piped into the co-pilot's side wing root air intake
which is connected to a "piccolo tube" that fite between the 2 radio stacks.
This lets cold air into the radio stack.

I've never had problems with avionics overheating, although my GPS has its
own little blower ("or you'll void the warranty...")
--
Aaron Coolidge

On Wed, 01 Dec 2004 02:33:05 GMT, Chuck wrote:

Hey Cherokee owners,

Has anyone run into a problem with the whole dash and all avionics
heating up???

Since I bought the plane this past summer, I thought all the heat
build up was due to our famous San Antonio summer weather. But I flew
into a cold front last night and the temp went down below 40F. Even
with it that cold -- the dash got uncomfortably hot after an hour and
a half flying.

The dash all around the center radio mounts, the radios themselves,
and the avionics stack in front of the co seat were so hot that it was
uncomfortable to put your fingers on it for more than a couple
seconds. I was under the hood at the time, so didn't take the time to
check the whole dash and didn't think to check on the pilot's side.
But the dash on the left side of the radio stack in the center was hot
too.

Has anyone run into this before? I've already checked the exhaust and
shrouds -- all OK. I'm going to spend some floor diving tomorrow to
make sure the heat and defrost vents behind the dash haven't come
loose. But they were OK a month ago when I was back there.

Thanks for any suggestions you guys can provide.


Chuck

Here's my WAG:

Depending on how many and what type radios you have, you may have what
I'll call a stack cooling problem. Electronics can create alot of
heat and if you don't dissipated it efficiently it could create a heat
condition like you describe.

Good Luck, and please let us know what you find.

z

On 30-Nov-2004, Chuck wrote:

Has anyone run into this before? I've already checked the exhaust and
shrouds -- all OK. I'm going to spend some floor diving tomorrow to
make sure the heat and defrost vents behind the dash haven't come
loose. But they were OK a month ago when I was back there.


My guess is that you are on the right track with the cabin heat/defrost hot
air source. Could be a leak in the scat tube ducting somewhere allowing hot
air from the heat muff to warm the panel from behind.

Let us know what you find.
--
-Elliott Drucker

I go with the leaking defroster theory. Our 172M when new cooked the
top radio in the stack so much you could hardly touch the front panel
during the winter. I used the pressure outlet of a vacuum jury rigged
with some duct tape to force air thru the defrost system to find the
cabin-defroster leak. Problem solved.

Other stuff we found - The 172M also had stainless steel cooling
plenums on either side of the stack, that were connected via 1 inch
dia scat hose to a small air scoop outside the aircraft. Tape on the
plenums covered the areas that had no electronic gear. We removed the
tape to match the revised setup. The scoop had only a 3/16 dia hole
thru the fuselage skin for whatever reason. We also drilled that out
to a larger size to get more plenum cooling. In hindsight that
probably wasn't necessary. We have maintained the plenum system
religiously even though the electronic shops suggested it wasn't
necessary.

The electronic stacks don't take that much power nowadays that they
could dissipate that much heat.

Chuck...

Hook up ground power (on the ground, engine stopped) and run the radios for
a couple of hours. This will IMMEDIATELY tell you if it's the defrost or
heat or just the radios.

DB

"Chuck" wrote in message
news
Hey Cherokee owners,

Has anyone run into a problem with the whole dash and all avionics
heating up???

Since I bought the plane this past summer, I thought all the heat
build up was due to our famous San Antonio summer weather. But I flew
into a cold front last night and the temp went down below 40F. Even
with it that cold -- the dash got uncomfortably hot after an hour and
a half flying.

The dash all around the center radio mounts, the radios themselves,
and the avionics stack in front of the co seat were so hot that it was
uncomfortable to put your fingers on it for more than a couple
seconds. I was under the hood at the time, so didn't take the time to
check the whole dash and didn't think to check on the pilot's side.
But the dash on the left side of the radio stack in the center was hot
too.

Has anyone run into this before? I've already checked the exhaust and
shrouds -- all OK. I'm going to spend some floor diving tomorrow to
make sure the heat and defrost vents behind the dash haven't come
loose. But they were OK a month ago when I was back there.

Thanks for any suggestions you guys can provide.


Chuck

Doodybutch wrote:
Hook up ground power (on the ground, engine stopped) and run the radios for
a couple of hours. This will IMMEDIATELY tell you if it's the defrost or
heat or just the radios.

If it is a radio cooling problem, and assuming he's getting atleast a
little cooling while in flight, ground running them for a "couple of
hours" is a great way of destroying them.

--- Jay


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