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-   -   Baffle Rubber Done Perfectly Wrong (https://vansairforce.net/community/showthread.php?t=104953)

RWoodard 10-03-2013 08:59 AM

When I purchased my Midget Mustang in [marginally] flying condition, the baffles were the same way--didn't even touch the cowling. Not to worry, however, as the prior owner/builder opened up the aft side cowl cheeks at the firewall to provide better flow and "it completely solved the oil temperature issues."

Some people's children...

flyboy1963 10-03-2013 09:04 AM

..what A&P?
 
...this all looks like the kind of fine work I may have done when I first worked at a local maintenance shop. I was 15, and I thought I knew all about aircraft, ('cause my Dad built one!)
Of course the engineer should be looking at all this prior to the cowls going back on, but just saying that a LOT or work is not done by him/her. Often they simply say " clean that engine, touchup the paint, and put those baffles back on..."
and walk away for the rest of the day.

HSANTIBANEZ 10-03-2013 09:12 AM

Some times when i think my work isnt perfect I take a look on the Certified planes at the hangar and always feel beter, it is very noticiable tha quantity of cessnas and pipers that have deficient baffle installations, but all that airplanes dont have complete cil by cil engine analyzers so they dont know that is bad, and the most important is they never have a problem in 20-30-40 years, so as a friend told me some time. "I only believe in God and Lycoming":)

rapid_ascent 10-03-2013 09:46 AM

I know this is obvious to you guys, but for those of us that haven't been in the guts of cowl can you clarify further the proper install details. I think I get the idea but it would be good to have the specifics. I had assumed that the baffle material was just flat material. I'm now getting the feeling that is not the case and that the curvature should point inward, the higher pressure area then forming the seal against the cowl.

Mike S 10-03-2013 09:51 AM

Quote:

Originally Posted by rapid_ascent (Post 813135)
that the curvature should point inward, the higher pressure area then forming the seal against the cowl.

Exactly...

rv7boy 10-03-2013 09:58 AM

I was introduced to the importance of baffle sealing when I witnessed the A&P who worked on my dad's 172 reach his arm through the cowl hatch doors and then through the cowl inlets to make sure the baffle seals were turned the right way (toward the airflow). Those baffle seals were much stiffer than what is shown in Dan's photos. They didn't appear to be factory original.

pierre smith 10-03-2013 12:18 PM

Yep
 
....and if you guys still getting to the baffling stage, cut it across the short width from the roll, you'll already have that 'built-in' curvature...installed curving inward.

Best,

walkman 10-03-2013 12:40 PM

Quote:

Originally Posted by DanH (Post 813068)
Clearly the bad baffle sealing has been found acceptable during several past annuals. This sort of non-sealing is very, very common in certified GA aircraft, which is why I don't give much weight to RV builder statements like "My CHT's are high, but my mechanic has checked the baffles and says they are fine". You've seen my usual response: "Post pictures".

Please allow some clarity; I don't wish to paint all A&P's with a broad and ugly brush. However, I do have a question, and it's just as applicable to RVs as any other bird. Is this or is this not considered an airworthiness issue? Is the mechanic who signs off such an obvious fail putting his license at risk? Or is this just something a mechanic must sell to an owner to get it done?

Why I've never understood aircraft owners who weren't extremely hands on in the maintnenance of their birds. Much more likely for you to be killed by a mechanics mistake in your plane than in your car.

I knew nothing about aircraft when I bought my first one the year after I graduated college. But I did every bit of work on every aircraft I've owned (under supervision when required). Sure, I paid more for the first few annuals or the first time I pulled a jug off than I would have to just pay someone else, but I figured i was paying for education and peace of mind. I still seek out and pay for that knowledge 23 years later.

Robert Anglin 10-03-2013 06:05 PM

understanding
 
I understand after reading Walkman and Roy's post that there are a lot out there putting together these and other "E.H.B's" who may not have a good grip on this one. It reminded me this is why we have "FAR's" and "AC" like part 23 and 41-13. Some of these came at grate cost to people and property. I have always liked the idea of the 150% rule and find myself using it for a lot of other thing other than aircraft. Helps keep my cost down in the long run and things just seam to last longer. I don't have any good "J.P.G.'s" of a seal installation. But if any one dose it would be nice to post them with a short how you did it.
Yours as always R.E.A. III #80888

N941WR 10-03-2013 06:26 PM

Quote:

Originally Posted by rapid_ascent (Post 813135)
I know this is obvious to you guys, but for those of us that haven't been in the guts of cowl can you clarify further the proper install details. I think I get the idea but it would be good to have the specifics. I had assumed that the baffle material was just flat material. I'm now getting the feeling that is not the case and that the curvature should point inward, the higher pressure area then forming the seal against the cowl.

The baffle seal material should be riveted to the inside of the baffles and curved towards the engine. Thus, when air enters the cooling inlets, it pressurizes the baffles and they seal against the inside of the top cowl forcing the air down between the cylinders, not past the fabric.

Here is a diagram I found on the net:


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