Baffle Seal Material?

[Rick_A]

Yes, I used the McFarlane Cowl Saver. I've got about 165 hrs on my plane and it's holding up very well. There is no sign of any wear on my upper cowl or on the baffle material.

It's is surface is very slick and the material is much stiffer then Van's black baffle material. The stiffness made it a little harder to get the top cowl on when it was new. It is too stiff to use around the air intakes, I used the stock material in those places.

I purchased the cowl saver install kit but I'm not sure if it was worth it. I used the aluminum mounting strips but I did not use the soft solid rivets that came with the kit. I used standard pop rivets with the mounting strips.

Making the mounting strips was a lot of work. I probably could have used the large head pop rivets in the Van's kit and saved a lot of time. I also installed mine with as few "breaks" as possible. I have one long piece across the back, and one piece sides from the rear corner to just past the front cylinder.

[Randy]

I have been chasing down a vibration that has been haunting me since I starting flying behind my new IO-375. It would get to oscillating like a harmonic, and sometimes go away etc. I found a few places that were potential candidates, one a place where the aluminum baffle made slight contact, another was the muffler making cowl contact. I got both of those areas fixed, but the darned vibration kept coming back.

On today's flight I thought I would try an extra cushion in the seat for a little different view out the front, I like it better. Especially since it helped me identify the problem. As I was flying along feeling the vibration again, I noticed a vibration in the cowl that I could see from my new seating position!

I landed and stuck my hand up through the oil door and could feel that the baffle seal material had blown back and was vibration up against the cowl. This is Van's baffle kit black material. My gap to the cowl is very close to 1/2" across the back wall where this is happening. I cut the strips at 3", and may have trimmed them down a bit afterwards. Maybe too much, I will be measuring tomorrow.

So I pulled the top cowl and made sure that when I put it back on the material was positioned properly. Sure enough, when I got home it was laid back again.

I will double check my gap measurements and will install some new material, I think. A little more study of the situation is needed to make sure I actually make this better. Just thought I would pass this along. At this point I am just happy to have finally pinpointed the vibration!

Oh one more thing. When I would remove the upper cowl the material would spring back in to it's proper position so the only way to tell for sure was with a bright flash light shining in through the oil door.

I am quite surprised the material can be forced back like this. I measured differential pressure earlier and it is good, but I did not expect to have it blow the material backwards. I am thinking of using some different material, but I have enough of the Van's black stuff to replace the pieces on the back wall where the problem is.

I had three separate pieces across the back, maybe they need to be stitched together, or maybe just go with two pieces etc?

Curious if others have had this happen and what they did to correct it.

BTW, no heating up problems occurred with this, just a very annoying vibration.

Randall in Sedona
RV7A, IO-375, WWRV200 @ 16 hrs on engine, still breaking in.

[rvbuilder2002]

The other materials that are popular as alternatives to the black garlock seal material are even more flexible so just changing to a different seal wont likely solve your problem. You need to correct the excessive gap. I would bet that in at least some area, you have more gap than you think.... once it blows through in one spot it allows the entire section to go.
A side benefit of the black seal is that it leaves black rub marks inside the cowl at contact areas. It is good to keep an eye on this to help detect areas that are not sealing properly, or where seals are getting mis-positioned like yours.

[N427EF]

It is an excellent material and holding up very well.
Only 320 hours so far but seems to do the job and as tight now as it was when new.

[Henryrifle]

Randy:

I had the same issue you are experiencing except my rear rubber is one piece. The rear edges were stitched to the rear edges of the side pieces and that has stopped the rear from blowing over.

Hank

[rightrudder]

Does anyone stagger the side baffle gaps a little to account for the torque reaction of the engine? I just want to do this right the first time!!!