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6061T6 or 2024T3 Angle for Engine Baffling?

avrojockey

Well Known Member
Patron
I have a cracked section of stiffener angle near oil cooler that needs replacing. I'm assuming 2023-T3 is what I need since its more fatigue resistant, but it appears everyone is out of stock, and Vans only sells 6061-T6.

Does it matter?
 
Just me

I would think 6061 would be fine, but I think you need to address why it cracked? Are you going to beef the area up, or somehow mitigate the stress that caused it to crack in the first place?
 
I just went thru this with my -7 after 220 hours. Cracked along the bend of the baffle that attaches to the cooler mount on the left (vertical) edge and also at the right side of the cooler mount in the little "box" that lines up the baffle line at the rear of the assembly.

The problem is that the assembly from the centerline of the engine to the outboard edge of the oil cooler is long and unsupported, and the weight of the cooler flexes the whole baffle assembly fore and aft during operation, eventually cracking the corners where the flex happens.

My fix was a 1/8" thick angle of 6061 at the bend and a newly built baffle plate (the one that surrounds #4 valve cover). A doubler at the small crack on the inboard side. Than I added a diagonal brace from the inside of the top valve cover bolt to the inboard top bolt of the oil cooler.

In the end, the angle is so much stronger than the surround assembly (baffles and mount) that the material used seems unimportant. Yes, 4 ounces added but as I read elsewhere ... it's strong enough now to pull the plane out of the hangar using the oil cooler as a handle!

We'll see. That's why they call it "experimental" !!

Cheers
 
Here are some 17 year old pics from my -9A that might help. Solid, no cracks.


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Vern
 
Yep, common problem. On my two RV-8s the the oil cooler mount baffle cracked at around 350 to 400 hours. My current RV-8 has a brace from the engine to the aft baffle, and that did not prevent the cracking from occurring. On both RV-8s we replaced the cracked parts and added a skookum angle there (a technical term!). The cracks have not reappeared on either RV-8, and my first RV-8 now has about 2300 hours on it and my current RV-8 has 1250 hours.

Cracks:

i-g7bmgBz-XL.jpg


Fix:

i-3Gx5HZR-XL.jpg



I'm surprised that Van's has failed to address this well known issue that many have suffered from.
 
This is the stiffener angle and the approximate location that cracked. Though mine was fabricated a little different where the crack occurred.

After I replace it then I'll take a look at the various fixes for this common problem.
 

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I like what rzbill did re oil baffle-mounted cooler support

rzbill has the most elegant solution I’ve seen IMO.

His post is at https://vansairforce.net/community/showpost.php?p=556594&postcount=28

The photos disappeared but I have them at https://photos.app.goo.gl/dWgDiTypWdJXSvqa8 The door analogy images are mine.

I imagine the J channel is the key feature. IMO reinforcing the corner of side and aft baffles is addressing the symptom vs the cause.

Others brace the rear baffle to the engine spine or extended valve cover screw, ref the thread linked above starting at post #1: https://vansairforce.net/community/showthread.php?t=73707
 
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I used steel angles that I made to replace the Al angles that cracked on my first RV8. I also used a fabricated steel angle for the horizontal part on the #4 baffle side, tied to the vertical one. I think it was about .30-.40 thickness. Probably weighed a couple ounces more, but didn’t crack. I just bought plain steel at Home Depot.
 
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