Good day all,

Today the temps were lucky to break into double digits. If it did, it surely didn't go very far into it. Of course, the wind chill was below zero. But it was a beautiful sunshiny day to get in the sky and burn off some more of those hours for the insurance company.

The one thing that was missing from the experience was warmth! I was wearing insulated coveralls during today's exercises, and so was my trainer. Equipped with ear-flap hats, gloves, and thick socks, we were good, but it was still cold in the cockpit, complete with the ability to see your breath!

Can I expect this to be SOP for winter Maule flying, or should I expect at least a reasonable amount of heat in the cabin? Both knobs were out and full blast (in theory). During our flight, I was told that there was an improved heat muff for this MX-7-180A, but I don't remember seeing it in any of the mod lists and the like. Sure would be nice to get some warm air flowing in there. I complained about the lack of substantial heat in the C-140 with its straight pipes, but it was a sauna in the cabin compared to what we experienced in the Maule today.

Thoughts and experiences are greatly appreciated.

~Chris

On my website I have a few ideas. http://www.montanabyair.com/Maule_Info.html

Do you have the aux heat kit installed? It's a 3rd heat duct from the right side tailpipe .

Wyflyer wrote:Do you have the aux heat kit installed? It's a 3rd heat duct from the right side tailpipe .

Unknown, but doubtful. I'll take a look and see what's on there.

Thanks!

From whom does one acquire the aux heat kit? From Maule or another source? Does it splice into the existing exhaust, or just wrap around it?

#1, remove cowling and check routing of all heat and cool hoses to appropriate firewall valves.
Check muffler shrouds are fastened reasonably tight. Use a 7"hose clamp to control vibration of shroud.
One shroud is dedicated for carb heat, the other for the cabin. A third is on the tailpipe and piped to another firewall valve. The heat valve is bypass type whereas the cool valve is not bypass.
#2, address the Complete cabin which is a low pressure area in flight thus sucking cold air in at any tiny gap.
Door knob slots are a big gap though they don't look it. Seal with tape or silicone.
Door frame fit and sealing strips are a common leak. Ace hardware self stick.
Landing gear attach points under fairings need sealing with tape or insulation.
Wingroot. Remove top and nose fairings and fully seal with insulation being sure not to foul cables and pulleys. Make sure no gaps. Tape around aileron cable through fabric area. Then broad masking tape all around the wing root, top bottom, front and back, between wing skin and fuselage.
Behind rear cabin bulkhead seal with insulation the headliner back piece fully up to the fabric skin on top. Close the left sidewall gap. Then fully close the gaps among cable groups under floor. Allow no air to move into cabin.

This will make a cozy cabin provided you do it carefully, do not have crushed scat hoses and have no restrictions over the heat duct outlets.

Thanks much for the tips! I'm sure you've given this advice a dozen time, and I saw it in a reply from a couple of years ago when I did a site search. I'll put this on the list of things to do.

Many thanks!
Chris

In my Maule, if I pull the cable for either heat, or cool air out all the way it actually reduces the desired airflow. About 3/4 out give me the max benefit whether I'm trying to heat, or cool the cabin.

Sounds like cable length adjustment problem.

Over the last couple of annuals we have replaced all the ducting in my M5. A lot was brittle ,most of it leaked but replacing it improved the flow of air and heat. The defroster vent was so bad I couldn't remove condensation some mornings. I guess that is to be expected with 20 year old ducts.

Even in a drafty cabin I stay warm below zero. The pilot's side will make my seat belt buckle hot on a long flight! Wouldn't want to be in the back though.

Cabin air leaks are the biggest contributor to cold Maule cabins in my experience. When Maule Flight rebuilt my MX-7-180, they taped up a lot of areas like the wing roots and replaced the window and door seals that became leaky over time. They didn't change the heat ducts or heat muffs at all but afterward even when it was very cold outside, the engine produced enough heat to warm the cabin to a comfortable temperature. I have an oil cooler winterization kit that blocks off about 3/4 of the oil cooler with a metal plate but I stopped using it years ago because it was too difficult to install and remove. Now I use metal foil duct tape across half of the inlet screen if it's cold enough to cause me concern about oil temperature. You need a long arm to reach into the cowling but it's relatively easy to apply or remove without taking the cowling off. The ideal solution would be pilot-adjusted cowl flaps and there are several posts in the past about this but it's a field approval and I don't think many owners have done this.

Aside from the holes near the landing gear struts for the ski release cables (AeroSki 2800), the biggest contributor is likely the lack of weather stripping around the windows. I think that's the first attack point. Then follow up with all the little holes after that. During April's annual, I'll take a look at other things while I have the plane apart.

I rely heavily on Carhart! I plug the holes around neck and sleeves, and keep the air from my head by putting insulation on it... the only limitation to this method is the length of the seatbelts. All the wind whistling around in the cabin keeps the windshield from fogging up.

Our recent trips this winter exposed some nice blasts of outside air coming in thru the door seals. Door seals on the list. Otherwise, stayed fairly warm; I fly with stocking feet (my boots complicate things too much ). The air coming in through the heat vent was hot enough to make the feet feel like the socks were melting...