Landing gear mounts

Hi, I'm finishing up some last jobs before mounting the engine on my QB RV7A. I need to backdrill 2 x AN509-10R12 screws both sides through the lower longerons but it's crowded real estate in there and the forward holes can't easily be backdrilled or accurately measured because F-902 is in the way. It's hard to get a close look at the ruler down there with bi-focal glasses

Any thoughts on how to tackle this? I thought if I backdrilled the aft one and someone tells me the actual distance between the centres of the 2 holes. I could draw a line forward and drill in from the side pretty accurately.

Thanks for any help. Merry Christmas from Oz to Doug and all the amazing people on this site.

https://www.youtube.com/watch?v=Y_YAmzI2o0k

Holes

I drilled mine early for that reason. My bolts are installed so any measurement would not be perfect. Hopefully someone will measure the holes on their tower, but if not, call Vans and ask the engineers to measure the mount holes for you.

Fixed

Thanks, Wirejock

I bit the bullet, assumed the shape of a 220lb pretzel and measured it. For someone's future reference: space between hole centres is 1"; I backdrilled the aft holes, measured and outside drilled the forward holes, bullseyes each time. 3x magnifying spectacles saved the day!

Drilling

Buy a 90 degree air drill. They make screw in bits that are short to long. Try brown tools or any other aircraft too company.