Fuel Cap Flange

[pilot28906]

I am about to countersink the fuel cap flange (T406B) and need to know how deep to go. I countersunk the tank ring (T407) deep enough that the rivets set well below the surface but the rib does not lie flat on the ring (the dimples hold it off). I am afraid that I will get the same with the cap flange and have leaks.

What have all of you folks done as far as dimpling the cap flange?

Thanks,

 

[WingsOnWheels]

Just dimple a piece of scrap and adjust your countersink until the scrap with the dimple sits flush. Make sure you use scrap of the same thickness as the "real thing" for the dimpled part.

 

[apkp777]

Machine countersink and install it with proseal. It won't leak.

 

[mcencula]

I went about .007 deeper than was required to make a rivet sit perfectly flush.