Tail tie down bracket installation

[cleve_thompson]

As I read the plans and manual, on a 9A, the tail tie down bracket rivet and bolt holes are predrilled (the bolt holes are just drilled to 1/8 in.) and the bracket is then installed on the forward face of the rear bulkhead and then the holes are drilled into the bulkhead in assembly. I don't think even my angle drill will get in there, particularly if I have to clamp the bracket in place. I was thinking that I would rather mark the bulkhead with the drilling pattern and drill into the tie down bracket from outside. I think that I can do this carefully enough that I should hit the bracket flange center close enough. I think that this will work but then I am not sure what to do when I then install the vertical stab and try to drill it in assembly from inside the tail.

HELP!!!!

 

[FredMagare]

Maybe...

I'm not anywhere near that part of assembly, but perhaps you could mark the hole patterns on a card (stiffer than paper) and place it on the back side of the bulkhead in the correst position. Drill the hole pattern slightly undersize. If alignment of the holes looks good, cleco the bracket in place and drill it to the bulkhead (from the backside).

Good luck.
Fred

 

[jlfernan]

If you already mounted the tie down bracket to the aft bulkhead, like I did, you can use a Taylor air drill. I bought the set from Cleaveland tools, http://cleavelandtoolstore.com/prodinfo.asp?number=ADT31. It is a combo mini belt sander and it comes with a chuck for drill bits. It is small enough to fit through the square hole in the F-714 rear deck to allow you to get to the pre-dilled holes in the bracket. It's a little pricey, but if you can borrow one or something like it should work.

 

[mikehoover]

Angle drill should work

I did the slow build fuse so the QB is more challenging here I suppose. The Tie down bracket on the slow build is already drilled/riveted to the bulkhead before the bulkhead is installed on the fuse. The bolt holes are still #30 at the time the VS is to be installed, so you would drilled from inside with #30, then drill from outside thru VS spar/double/bulkhead/tie down bracket to the actual bolt hole size. Any off-angle (if slight) drilling of the #30s thru the tie down/bulkhead from inside thru the VS spar/doubler should be eliminated by drilling the final size bolt holes from outside. If I remember, getting angle drill in there was a bit of a challenge, but can be done. Use the longest threaded bit you can to avoid interference with the tie down bracket raised middle section.

Here is part of my log entry for this:

Drilled the four bolt holes in the bottom of the rear spar of the VS thru the aft bulkhead. This was difficult as I had to drill the initial #30 pilot holes from inside the fuse with the angle drill. Once done, I enlarged to #21 and then to 3/16.

Did the enlargening from outside of course.

 

[craigvince]

Tie down bracket

My friend Tom is building an RV-7a QB, and was working on his tie-down when I was at his hangar a couple days ago. His bulkhead (QB) was riveted on with a few temporary pop-rivets. All he needs to do is drill out the temp rivets and that bulkhead comes right off. He can then match-drill everything (including the VS) on his workbench.