Shock Strut Boots

[Nev]

For anyone who has struggled with a CO issue as I did during the test flying - I remade the shock seals twice, taped all the boot panels from the inside, then systematically plugged holes throughout the fuselage. There's a lot of them in these type of aircraft. None of this worked sufficiently.

Finally, I lowered the exhaust pipes. This was very easy to do and took 30 minutes, simply pivoting them down around the universal joints a small amount, and also twisting them so that the elbow sat lower. I had originally kept them tucked up close to the tunnel to be streamlined. They're now sitting about 2" lower, and my CO monitor reads zero when the mixture is full rich. Even when I removed the tape from over the hole for my gascolator drain, it still reads zero.

I plan to get some short curved extensions made up to further direct the exhaust away.

[robcaldwell]

I've considered lowering my pipes as well. I have the same CO issue. Let us know what you come up with for pipe extensions. Is this something from Vetterman?

[jaredyates]

Clint can sell you a set of bolt-on turndown angles. Let me know if you have any trouble getting in touch with him.

[Nev]

Rob - at this stage I haven't added any extensions, I've just loosened the support brackets enough to lower the pipes. I was able to get a couple of inches movement. Worth trying this first as it made a large difference.

[Bcone1381]

I referenced an article in post 10.1. Conclusion is Negative pressure in the fuselage can draw exhaust into it. They sealed a hole in the aft bulhkhead to fix there problem.

I've saw one fix where a NACA vent turned backwards was installed on the belly under the cabin to create suction. It was able to capture the contamination and vent it overboard keeping air above the floor fresh.

Nev discovered another solution that maybe Piper dealt with in the same way....I mean look at that thing! Its got to be 12" long! Holy Smokes!!


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[marcusofcotton]

Actually not Piper exhaust, it's Sutton aftermarket. Might see such on a Bearhawk with a light engine/prop combo someday - you never know...

[jonmiller0]

Has anyone done the backwards NACA duct? I saw some nascar video talking about it...https://www.youtube.com/watch?v=rtEsdUzlIEk

Might work, but I'd hate to cut open the belly of a good airplane, make it colder in winter, all for a fix that might not work. Just desperate to find a solution to the CO

[gregc]

Cessna 180/185s have a tail cone air scoop that was added via a service letter to reduce CO in the cabin. The kit was free and even included the princely sum of $4 to cover installation labor (in 1962).

[svyolo]

Interesting. Just create a slight positive pressure?

[Nev]

https://www.kitplanes.com/diy-firewall-boots/

[Light&Sweet]

Creating positive (fresh) air pressure in the cabin would keep the outside out, too.

[alaskabearhawk]

What I finally came up with. Certainly not as elegant as some others have done, but it should work. I need to get this thing done!

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[AKKen07]

Looks really good to me!

[TrueAirSpeed]

I used these https://www.lowes.com/pd/Oatey-Maste...er/5001984937? or these

Figured if they last 15 years on the roof of a house, they'd work.

[jonmiller0]

can you post a photo of these installed?

[Gerhard Rieger]

Great to see all your ideas, here is mine

[whee]

Maule boots fit and look pretty good.

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[jonmiller0]

Where did you find those - they look sweet. I still need to meet up for an Idaho Bearhawk day with ya. In annual right now...great timing.

[jaredyates]

Maule boots fit and look pretty good.

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Those do look good Jon, do you have any type of reference like a part number or anything?

[rv8bldr]

Since I have a Maule M5-235C, I bought the parts catalog :-) Note that this is leather (Naugahyde?) and covers the bottom of the control column in the cockpit. I believe you can buy it as a complete assembly (no sewing or anything required)




Maule Boot Top.png

[Bcone1381]

https://bearhawkforums.com/forum/bearhawk-general-discussion-news/58045-shock-strut-cutout-splitting-the-boot-cowl-section

That link has shows a thread with the strut cover and rubber seal that Bob Designed. The drawing can be found in Beartracks.

My origonal was made iaw the drawing with a rubber seal and round hole. Don't cut the sealant hole round like the Beartracks Drawing shows...it way too big. When the gear articulates the hole opens up.

Stinger (LSA scratch builder) used 1/8" thick silicone sheet (Amazon). I installed his design today and no comparison to my rubber (from an innertube) seals. Silcone can really stretch. Cut the hole rediculously small & oblong...it will fit nice and tight over the strut.

Dont drill holes in rubber....sharpen a tube end with a file and cut them using a drill.

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[DBeaulieu]

Nice work!

[rkennell]

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I used oil resistant neoprene from Granger that met the specification spelled out in Beartracks. I decided to try 1/8 in on one side and 1/16 in on the other. I looks like it is going to work but I am a ways from flying. It sounds like exhaust placement has more effect on CO levels then anything else.

Roger
Companion QB

[rkennell]

Brooks, I like the way you cut your hole in the silicone

[Luke68]

Figured I would share how I did mine they are made out of canvas with a vinyl backing I believe it’s a type of marine fabric. Very lightweight and seem to seal pretty well