Back drilling landing gear mount extention

[cleve_thompson]

I have bolted up the landing gear mount to the bulkhead and was ready to back drill the holes through the extension in the weldment through the stiffiners and skin according to the plans when I found that the forward predrilled hole in the extension is under a flange. I can't get to it to backdrill it. I was thinking that I could move aft and drill another hole. What did you do?

 

[Finley Atherton]

From memory the pre-drilled hole in the weldment extension is 1/8". So, I first drilled a 1/8" hole in the flange where I guessed/calculated that it would line up with the hole in the weldment extension. Now you can get to the hole in the weldment. Drill a 1/8" hole right through to the outside. Finish by drilling #12 (from memory) from the outside. You may have to enlarge the 1/8" hole you drill in the flange a little to get the drill to line up with the hole in the weldment extension.

Fin
9A Australia

PS. Just went and had a look at the area. If I was doing it again I think I would just cut the corner off the flange to allow access.

 

[Pmerems]

Drilling tip

Here is how I did it.

http://www.experimentalaero.com/Gear Mount Drilling.htm

I hope this helps.

 

[Jekyll]

Trim the flange for access. It takes all of 2 minutes.

Jekyll

 

[cleve_thompson]

Paul, I used your template method on the right gear mount extention and it worked perfectly but it was a little scary. Now to the left side.
Thanks all!

 

[cytoxin]

measured and drew

well i just measured fwd and kept the line parrallel and drilled 1/8, first bit came through perfect. gotta love vans cnc. the aforementioned method by
Pmerems seems even more fool proof.

 

[Steve]

Use Finley's eyeball method. Good to go.

Steve