Flap Air Leak?

[riffelj]

I'm trying to figure out how to plug up the airleak around the flap pushrod that exits the fuse on my RV7. Anyone solved this one?

[ao.frog]

I sealed the corners in the box which houses the flap pushrod with RTV.
The RTV must the replaced on the annual, because you've to open the box, but that's easy.

[Bob Axsom]

I'v heard of this problem but I don't fully understand the conditions. Is the leak present all the time or only when you lower the flaps for example? How do you know the leak is around the flap pushrod (depending on the answer to the first question the answer to this one may be obvious)? I have no leaks from this area into the occupant area of the cockpit that I am aware of. Two things I have done that may be different than your airplane are:

- The entire baggage area other is upholstered. I bought the carpeting, upholstery material and upholstery instruction video from Becki Orndorf (sp?) and did it myself. The covers over the flap mechanism at the sides of the baggage area are covered with upholstery material (no foam here) which is glued on with 3M upholstery adhesive. The material wraps around the edges of the covers and compresses into a good air tight seal when the mounting screws are installed.

- I formed a step in the inboard edge of the lower flap skin so that when the flap is retracted the flap skin closes on the bottom fuselage skin. My flap skin inboard edge is not long enough to cover the flap pushrod opening in the fuselage so I riveted on an extension "tab" to the flap skin specifically to cover the opening when I installed the flaps.

When I lower the flaps I have to look at them to verify deployment - there is no air change in the cockpit. I hope this helps but since I've never experienced the problem myself I'm shooting in the dark.

Bob Axsom

[carguy614]

I used soft foam blocks made from black urethane. They come on the door edges of new cars to keep the transporters from dinging them. I cut a rectangular slot in the block, and glued them to the skin over the flap hole. The rod rides up and down in the slot in the block real nice, and squeezes shut to block out any air. Any good quality dense foam scrap should do the trick, Works like a charm. Sorry, no pics till annual time!!

HTH,
Chris

[riffelj]

Thanks all.

Bob, the problem is both when the flaps are up and down. There's a reasonably good seal between the flap bottom skin and the fuse bottom when the flaps are up. But there is clearance for the flap heim joint in the fuse side (maybe I cut mine bigger than some). I've also got a gap between the flap inboard edge and the fuse so I don't scuff paint. The result is that at speed the air evidently goes between the flap/fuse, around the flap heim joint into the flap bar box, out the flap bar hole into the baggage area.

The foam/rubber "plug" around the heim joint sounds interesting. I'm assuming it was 'closed cell' foam? Any issues with water retention/corrosion on the heim joint?