How to fix elongated bolt holes on steel fitting?

[jtrom]

My project plane (wooden plane) has a .063 steel bracket made of 4130 that mounts the horizontal stabilizer to the vertical fin. It's quite a complicated bracket and would be difficult to remake and mount since the aircraft is already skinned in plywood. A few of the holes have been mis-drilled (looking like elongated bolt holes). Can these holes be welded up and re-drilled? Is that a feasible repair in the aviation world?

[Frank Giger]

Bad news.

"Mounts the horizontal stabilizer to the vertical fin," means it's a very important bracket. I wouldn't screw around with this - it's a do-over.

[crusty old aviator]

How much material is left between the edge of the buggered hole and the edge of the fitting? If it's 3/8" or more, you could ream it out just big enough to press in a bushing made from 4130 tube, but you'll need to sandwich it with AN960L washers. The problem with welding a high-stress part is that you'll have to re-heat treat the fitting after welding and machining the correct holes. I don't think your daughter's E-Z-Bake oven will accomplish this. As Frank suggests above, the best course of action will be to remake the part, employing all the lessons you've just learned from the buggered up one.

[vaflier]

Would drilling through the pieces clamped together and going to a larger bolt be an acceptable way to deal with this????.

[jtrom]

For the record, this was an abandoned project I am trying to finish, so this was done by the previous builder. I'm trying to make it right :). The bolts that go through the bracket also go through the spruce vertical fin spar, which has aluminum bushings pressed in it where the bolts slide through. So making a new bracket would require drilling out the holes in the wood spar with the bushings and filling the holes with wooden dowels and completely starting over. There is no way to locate the existing holes in the fin spar to a new bracket. So I guess my new question is - is it OK to fill holes in Spruce with a dowel and epoxy and redrill a hole?? I'm talking 1/4" dia. holes through 3/4" spruce.

[martymayes]

So I guess my new question is - is it OK to fill holes in Spruce with a dowel and epoxy and redrill a hole?? I'm talking 1/4" dia. holes through 3/4" spruce.In the FAA AC 43.13-1B, the acceptable repair methods are splicing in a new spar section or replacing the spar.

If otherwise feasible, might explore the bushing in the bracket option crusty suggested.

[Frank Giger]

Would drilling through the pieces clamped together and going to a larger bolt be an acceptable way to deal with this????.

Hmmm, this would probably be my fix if I could get away with it, particularly since there's a bushing through the wood. It'd be tricky but could be done. Break out the AN5 bolts!

[martymayes]

Hmmm, this would probably be my fix if I could get away with it, particularly since there's a bushing through the wood. It'd be tricky but could be done. Break out the AN5 bolts!

Well, if you drill it with a hand drill you'll need one heck of a drill guide as well as something to fill the hole in the bushing. Othewise, expect the drill to walk from the desired location and follow the path of least resistance.

[dedgemon]

I dont know the specifics of your airplane and bracket, but in general welding a hole in 4130 and redrilling should not be a problem as long as you maintain edge distance etc. This is actually pretty common.