Avionics cooling

[Don Jones]

I have noticed my GPS is running pretty hot since it has no cooling fan installed. My airplane has a tube off of one of the air vents for avionics cooling which is capped off in the right kick panel. Is there any downside to using this? It just seems too easy to be a good solution. Advise anyone?
Don

 

[Let'sgoflying!]

Some of the GPSs (I think I read G430/530) require cool air supply. It should say in the installation instructions what is needed and what is acceptable.
Same with the cooling fan, if any of the aircraft records have the manual/notes that came with it- they should say what the fan can do or tolerate. I'd bet it would work and be a good idea.
In my old Viking, genius Guiseppe designed ram air cooling (I think it was him).
Air is tapped orf the pilot's wemac and ducted to both sides of the radio stacks through tiny holes.

 

[trombair]

the only problem with using ram air from outside the aircraft to cool avionics is the possibility of spraying the guts of your expensive avionics with rain, sand, dirt, dust, bugs etc. that's why avionics fans are preferred.

in a homebuilt i suppose one might try to invent some sort of centrifugal separator (ala turbine inlets) but in certified a/c you'd have to go with the TCDS or an STC.

although approved avionics fans do seem a bit over-priced to me, it's a one-time expenditure that can only help the longevity of your over-priced aircraft radios.

what the heck, it's only money.

blue skies,

 

[Skip Miller]

the only problem with using ram air from outside the aircraft to cool avionics is the possibility of spraying the guts of your expensive avionics with rain, sand, dirt, dust, bugs etc.

Hop on over to the Red Board and ask Dr. Bruce Chien for a copy of the article he wrote for Aviation Safety mag about his IMC flight where the electronics were shorted out by water from an exterior vent.

-Skip

 

[Let'sgoflying!]

There must be design variations, I have had neither bugs nor water enter the avionics in mine. And as it is tapped off the fresh air wemacs, I think I would have gotten some in the eyeball by now!

 

[Don Jones]

There must be design variations, I have had neither bugs nor water enter the avionics in mine. And as it is tapped off the fresh air wemacs, I think I would have gotten some in the eyeball by now!

Yea, this one is tapped in right behind the co-pilot vent, never had water, bugs, etc. coming in there either. I looked at the install manual for the GPS and it says no cooling air is required (Garmin GNC300XL) but has a provision on the back of the tray for it. I am waiting to hear what Bruce has to say to see what his issue was. I recall something about it, seems his took air off the base of the windscreeen in cowl area or something like that, Iv'e slept since then.
Don

 

[gismo]

There must be design variations, I have had neither bugs nor water enter the avionics in mine. And as it is tapped off the fresh air wemacs, I think I would have gotten some in the eyeball by now!

I've never seen a ram air avionics cooling inlet that didn't allow moisture to come in if you fly in heavy rain.

You know, I think I've got a brand new 3 port avionics cooling fan around here somewhere that I'd part with pretty cheap.

 

[Nathan Miller]

Wow, yeah, so this thread is 15 years old... but today is a rainy day today and it got me thinking of my ram air avionics cooling system in my 172N.

My car has a side scoop air intake (mid-engine) with an air/water separator. I wonder if such a thing exists for avionics in a certified bird(?).

It may just be cheaper and easier to cap over the intake vents on the sides of the plane and reconnect the scat tubes to a 2 port avionics cooling fan (likely, 3 port with that 3rd one capped off since I have yet to find a 2 port fan.



The top 3 Garmin units have integral fans. The bottom 3 Collins units (2 navs and #2 com) are original to the plane and pretty much are the o ph ones who need the ram air cooling. I rarely use it. Wondering if I'd be okay just plugging the intake(?)

Thoughts?

 

[MooneyDriver78]

I have a cooling hose off the wemac vent as well, it rises about a foot and is not directly attached so any moisture will just fall to the floor.


Tom

 

[Bell206]

Thoughts?

All the avionics installs that I've been around that required supplemental cooling went with some sort of avionics cooling fan with a thermostat. No external air source was used. If the over all cockpit temperatures were also high then the addition of some sort of window sun shades were required when the aircraft was parked on the ramp. This was an on going issue with some of the newer helicopters along the GOM and was finally cured with the above method.

 

[kshaw]

I had my IA install a Sandel three port cooling fan to my Warrior and one of the three ports goes to the Garmin 430w. Although our Cherokees were initially outfitted with cooling from the outside vents, that technique has fallen out of favor by avionics manufacturers. One of the advantages of the fan is that cooling is available as soon as the radios are started and not dependent on being airborne.

 

[bnt83]

This is one area where the newer Garmin units shine IMHO, example GTNs pull air from the pilot side of the instrument panel through slots in the sides of the bezel and dump it behind the panel, rather than blowing hot air behind the panel into a hotter unit.

That all being said even a multiport blower behind the panel will work well, we have them in both our aircraft. I have a hose blowing on the stupid ancient wire wound rheostats too.

 

[NordicDave]

the only problem with using ram air from outside the aircraft to cool avionics is the possibility of spraying the guts of your expensive avionics with rain, sand, dirt, dust, bugs etc. that's why avionics fans are preferred.

Correct! In fact READ any Garmin GPS installation guide, as they specifically warn the warranty will become null and void should for any installation use an aircraft's ram air for cooling.