7A Main Gear Mounts #!?@#!?@

[Pbr47906]

My post on the difficulties I had installing the main gear mounts on N277PM. Pictures attached.

On the center section, if you have installed the nut plates, remove them; if not, don't. The nuts interfere with installing the mounts. The elliptical hole in the bottom skin, enlarge it more than shown on the template on drawing 34. Next, get out your step drill and enlarge the holes in the mount a couple of thousands.

Drawing 34 also calls for AN4-12A bolts. 12A's are too short, go to 13A's instead. For that long reach down to install the washers and nuts between the F-704 sections, I used a magnet to locate both the washer and nut, then to tighten I clamped a 7/16" wrench in vise-grips. It works very nice. A couple of other things, stand up slowly to let the blood drain from your brain and be sure to wipe up the profuse amount of sweat from the bottom skin.

Now I need some advice; how do I get a drill the hole behind the vertical frame member?

Paul
N277PM
LAF

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[AltonD]

Avery does not show a picture, but please take my word for it: Washer wrenches are worth their weight in gold.

http://www.averytools.com/prodinfo.asp?number=23800
WASHER WRENCH SET Slip washer in place with ease. Precision cut from 301 full hard stainless steel .042” thick. Wrenches will always maintain their rigidity and tension. washer snap into position and are held firmly in place. Fits most commonly used aircraft size washers. 4 pcs. wrench set. Storage pouch included.

It is spring steel that the washer snaps into to allow you to position the washer where required. control surfaces, stick controls, and a bunch more places they are great for.

 

[UnPossible]

Now I need some advice; how do I get a drill the hole behind the vertical frame member?

Paul - I don't remember for sure, but I think I made a rough template out of scrap aluminum. You can drill the one hole without any trouble. I used the template to drill a small hole, hopefully in the center of the hidden hole.

From there you can walk the hole to the middle as you drill it up.

Hope this helps,
Jason

 

[Michael Burbidge]

Measure carefully...

I followed someone else's advice on the forum. I first match drilled the hole that is not behind the bulkhead. I then drew a line parallel to the bottom of the skin that intersected the hole that I match drilled. I then measured 1 inch ( on the RV-9, the holes are exactly 1 inch apart, verify it is the same on the 7), carefully from center of match drilled hole and made a mark on the parallel line I drew. I punched on the mark. I then started with a 1/16 inch bit and drilled from the outside. I looked on the inside to make sure it went through the center of the hole in the gear mount and then just increased the bit size gradually until I was up to a #12. I fretted a lot about this, but it worked out very nicely.

 

[Bavafa]

This is meant as an exercise to build patience, it prepares you for the canopy.

Paul - I don't remember for sure, but I think I made a rough template out of scrap aluminum. You can drill the one hole without any trouble. I used the template to drill a small hole, hopefully in the center of the hidden hole.

From there you can walk the hole to the middle as you drill it up.

Hope this helps,
Jason

This is exactly how I did it and it was relatively straight forward.
You also need to shim any gap that might be between this area and the fuselage. There is also a washer that has to be grinded off on one side that goes between the spar and the mount. I had forgotten about that and had to reinstall the mount once again.