FAB Seal questions

Pilottonny · #1 10-09-2009, 01:59 AM

I am currently installing the Filtered Air Box. I was wondering how difficult it will be to get the cowling on and off with the BAF-Seal that will be riveted to the FAB-Snout and needs to wrap around the Cowling inlet. Also I see no reason to have the top (straight) part shortened, as is mentioned in the plans, because the cowling will just butt up against that. The problem is in the seal that have to wrap around the sides and bottom.

If the sides and bottom seals would be riveted to the cowling inlet, instead of to the FAB-snout, removal and installation of the cowling will be a lot easier, I guess. Has anybody done this?

What about those pop-rivets, do you all have these sticking into the inside of the FAB-snout?

Regards, Tonny.

jsharkey · #2 10-09-2009, 06:01 AM

.....I'm running without a seal for now. There is a ~1/4" gap, everything seems to work fine and the cowl is easy to take on and off.

Similarly I haven't fitted the L & R baffle ramp seals to the lower cowl and cooling is just fine also. If anything it's too good as the temperature here in the NE begins to drop and I may need to block the flow to the oil cooler that is mounted on the LH aft baffle wall.

I decided since I haven't painted the cowl yet and since I would have it on and off many times during Phase 1 that I'd leave the seals off and see how it worked. So far no problems. Perhaps I'll gain 1 mph when I fit them

Jim Sharkey
RV6 Phase 1

kentb · #3 10-09-2009, 06:16 AM

when the seal are added to the front of the cowl. But you will need that to get the best control of air flow into the engine.
As for the lack of heat in the oil cooler in the winter time, I added one #3 bolt to the side baffle above cyc # 4 and when it get cold I put in a piece of baffle seal that partially blocks off the cooler. When it gets colder I exchange that for one that blocks off as much of the cooler as can be covered.

Kent

RV10Man · #4 10-09-2009, 06:31 AM

On the -9A, it's not really hard to get the cowling on with FAB seals on. We just stick our finger in there and work the seal around the outside while putting lower on. Kind of use your knee to help hold the bottom up.

Marshall Alexander
RV10 N781DM

flion · #5 10-09-2009, 07:52 AM

I believe the idea of attaching the bottom seal to the cowl inlet has been tried before; a forum search should yield some results. I'm not sure how well it worked. I thought it might allow air to escape more readily than the way it is in the plans. I ended up with a 1/2" gap which lets the cowling get past the seal easily enough and is pretty tight with the cowling in place. Yes, the shop heads of the rivets are inside the inlet; no other choice, really.

It's not really that hard to get the cowl on once you have it trimmed where you can get it past the seals at all. I do it by myself; I just rest it on the nosewheel pant (another place we nosedragger guys have an advantage

) and use my knee to push the inlet while my hands guide it up at an angle so the inlet slides into the seal at about the time the rear of the cowl meets the bottom skin. One advantage I have with the 1/4 turn fasteners is the fastener body will catch in the receptacle so I can then lift the front that last couple of inches and get one of the top fasteners to catch. Then I just make sure the ramp seals are in place and go to the back and start locking the fasteners.

My baffle ramps have a tighter gap, about 1/4", than the scoop inlet; more important to ease of putting on the cowl is to be sure the ramps are maybe 1/8" low. My initially perfectly level ramps tended to push the seals up to form an early air dam; lowering them makes it fit nicely and probably keeps engine vibration from pushing the seals up intermittently in flight.

trib · #6 10-09-2009, 10:12 AM

Like the others have said, it's not difficult to install the lower cowl using your fingers through the inlet air opening to position the seal. Regarding pop rivets, if you attach the seal to the cowl, the pop rivets are then protruding at the cowl opening, which would be much more visible. You could orient the rivets so the finish end is in the FAB opening,using backing strips on the seals so they don't pull though. This will eliminate the effect, both visible, physical and mental.

On butting the FAB to the cowl opening, this seems like a very bad idea. When the engine cranks it moves significantly on the mount. Pressure between the fiberglass cowl and FAB during this time will likely end in some damage.

Pilottonny · #7 10-11-2009, 09:08 AM

Thanks for the replies. Well......... this is it!

Made two backing strips and put the pop rivets in from the inside. Left about a 1/4 between the "snout" and the air inlet, as suggested.
Without the spinner on it was easy to get the cowling on. I gues it will not be to bad with the spinner installed, as well.

I had to modify the FAB to get it ligned up with the air inlet. See where I cut its neck and layed up a couple of layers of glass?

While I was at it, I also installed a brace, attached with one of the throttle body nuts, since a lot of people complain about the top plate cracking due to vibrations. (no,.... it is not touching the fuel line!)

Regards, Tonny.