Smoking rivets

RV-4 Smoking rivets.

2 foot trail from several rivets after 45 minutes or less of flying.

No heavy G loads.

Location, bottom of fuse, center fuse seam between main wing spar and rear spar. It is the the cut you make, remove a long skinny wedge and splice back to make the big bottom sheet contour to the bottom of the fuse.

Rivet holes were machine counter sunk not dimpled.

Aircraft total time 935 hours. 1993 build.

No other smokers on the airframe. Aircraft is painted.

Options?

(a) wipe it off and keep flying

(b) gain access to shop heads and drive the rivets a few taps from the bottom.

(c) drill out smokers, install new rivets

(d) drill out smokers, install oops rivets ( larger shank, same head )

(e) other ?

Thank you in advance,

Mike

Other

asav8tor said:

RV-4 Smoking rivets.

2 foot trail from several rivets after 45 minutes or less of flying.

No heavy G loads.

Location, bottom of fuse, center fuse seam between main wing spar and rear spar. It is the the cut you make, remove a long skinny wedge and splice back to make the big bottom sheet contour to the bottom of the fuse.

Rivet holes were machine counter sunk not dimpled.

Aircraft total time 935 hours. 1993 build.

No other smokers on the airframe. Aircraft is painted.

Options?

(a) wipe it off and keep flying

(b) gain access to shop heads and drive the rivets a few taps from the bottom.

(c) drill out smokers, install new rivets

(d) drill out smokers, install oops rivets ( larger shank, same head )

(e) other ?

Thank you in advance,

Mike

Click to expand...

Mike... that's pretty loose along that joint to make a 2 foot trail...

I think I would do (e) ....

Add new rivets equally spaced between the existing rivets. Preferably dimple the skins - can be done with two dies, a heavy block inside, and hitting with your rivet gun on the outside... or, if it doesn't offend your sensibilities, use 1/8 round head rivets....
No-one is going to see in that location, and the air is pretty turbulent there anyway...

Then do (c) - but just to fill the holes and stop the smoking.

I'm guessing they were probably over countersunk a few thousands during the original construction, or the shop heads are too small...
Whatever, they certainly are no longer holding the seam together firmly, and need to be replaced/fixed...
The holes are now oversize, since the "smoke" is actually aluminum dust.

gil in Tucson

I like the button head 1/8 rivet idea but if you can't stand it then another idea would be to drill the rivets out if they are currently 3/32 rivets and enlarge the holes to 1/8.... then drive 1/8 flush rivets. They will of course stand "proud".... the final step being to shave the excess rivet head flush with the surface.... this puts a very tight rivet into the hole and they will not move.

I would inspect what you have, first.
Look at the shop heads and see if they were properly set in the first place. If not, then you can try to finish bucking them. (But putting in a new rivet would be pretty simple, now that you have gotten this far.)
If the shop heads look good, an alternative would be to drill them out and replace, either with a new rivet of the same size or an oops or pre-squeezed rivet if the hole is enlarged. If you go with a new rivet, you may also want to put some proSeal on it when you install it. (As a side note,I believe that the AF has all rivets on the new T6s ProSealed as they are bucked.)
Of course, you could go to the next size rivet if you need/want to.
Your path forward will depend on what you find on inspection, so don't make any rash decisions until you do that. It may become obvious what to do after you see the whole picture. (From both sides!)