Air Inlet Seal

Ironflight · #1 09-25-2005, 02:02 PM

Now that we have disposed of Rita, I can turn my attention back to my inspection next saturday! I only have one funny that has me bothered, and I am wondering if anyone has seen this and knows the cause.

Every time I do an engine run, the corner of the airseal fabric between the air box and the cowl inlet "herniates", as in the picture below:

I can tuck it back in with the edge of a screwdriver, but the next time I run, it does it again - same place, same amount. Obviously, this is caused by relative motion between the engine and cowling. And an obvious fix seems to be a longer piece of airseal fabric, but obvious isn't always right.....any other suggestions? Note, I do have little slits in the seal to make it easier to put the cowling on and off, and it is a very tight fit with very good static alignment.

Paul Dye

robertahegy · #2 09-25-2005, 06:08 PM

I did not put any slits in my fabric and the fit to the airbox is very tight. I think the fiberglass tube I made is longer than yours, making the "tunnel" very close to the end of the airbox. Maybe you need to try to make the fabric fit without the slits and/or make the inlet deeper into the airbox. I have had no problems.

Roberta

sf3543 · #3 09-25-2005, 07:48 PM

I had a slightly different set up for sealing the airbox to cowling inlet that worked well for me and was easy for getting the bottom cowling on and off. Basically, I fit a flat flap of fabric to the top of the airbox inlet and a "U" shaped piece to the ram air inlet on the cowl which was held in place by a larger hose clamp. The top of the "U" was sealed by the flap on the airbox inlet. Anyway, it allowed you to take the cowl on and off with out having to mess with this part and I never had a problem with puckering of the fabric.

RV7Guy · #4 09-25-2005, 08:33 PM

Hi Paul,

I haven't run mine yet, but like Rita, my space between airbox and is very small. Also I worked very hard to make the transition is perfect. Long process but I think it will be worth the effort.

Another thought, I would take some time to sand the inlet smooth and get rid of the sharp edges. May not sound like much but these edges can really cause some turbulence in there that could be pulling the seals.

You may need to add to the fiberglass so it is closer to the airbox.

Darwin N. Barrie
Chandler AZ

Ironflight · #5 09-25-2005, 11:04 PM

Thanks for the ideas folks...I am going to look at it again tomorrow and see which I'd like to try. I like the idea of putting the U-shaped bottom piece on the cowl instead of the air box. The fiberglass tube actually lines up very well - it looks displaced in the photo because the seal is goobering up the fit. The clearance between the end of the fiberglass and the airbox is about 1/8". I'll mess with it a little more.

Paul

RV7Guy · #6 09-26-2005, 08:37 AM

[quote=RV7Guy]Hi Paul,

I haven't run mine yet, but like Rita,

Whoops, should have said, "Like Roberta,"

Had a pop up arrive for Rita relief as I was typing!!!!

Darwin

Ironflight · #7 09-26-2005, 11:36 AM

Just to close this out, I put on a slightly longer piece of airseal in place of the first one, and cut the slits a little shallower, plus didn't put a slight near the lower "corners"....ran it up, and it stayed in place! Now I can concentrate on gettign ready for the inspection!

Paul

P.S. - I plan on doing more fiberglass work - like smoothing the inlet - once we get flying, it gets cooler, and I get ready for paint. We've got a heat index of 110 degrees today - too many therms for tedius work!