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Jekyll

Well Known Member
Tonight's project was to install main gear mount fittings in my 7A QB. I started laying out the through holes but it appears I must trim away portions of the wing box lower front flange. I was a bit uncomfortable cutting into the wing box flange without getting some insight.

Is this correct? It looks like I will need to take out a section about .25 inch deep and about 1 inch long.

Just call me shy about cutting in to the box without a second opinion.

Jekyll
 
Yes, you'll have to do it. Van's templates are a little undersize. Sorry, I didn't take a picture... if you search on this site, I think you can find one.
 
Yes, maybe

If you mean the hole in the skin for the leg, then yes, you have to cut into it, even to the extent of cutting into one or more rivets (QB). But I'm not aware of any other place where it would be acceptable to cut into the spar structure. On mine, the hole ended up bigger than needed for the leg receiver because of the difficulty of inserting it into the hole caused by the shape and size of the gear weldment bumping the side skin and/or the spar-box. Van's says to Pro-Seal it later for the gaps.
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IMG_1388.jpg
 
Jekyll

Agreed. You will have to remove some of the flange in that small area. Below is mine from the outside, sorry no pic from the inside. :mad: The steel socket weldment now covers the cut away. I used a Dremmel tool with a HHS "milling" tool -- my term) to remove the annodized material and skin to very near the edge of the rivet shown above socket. I, too, thought it excessive at first, but after thinking more about it, the construcion of the steel socket weldment and the way it is installed with all the bolts makes the area SUPER strong even though some of the aluminum was cut away. Just do it, but go slowly while you "cut and try" It took me a couple of hours on each side before I was satisfied.

You want to leave a little space around the gear socket (through the skin)to allow for the radius of the weld, too. I have seen some RVs with the gap, about 1/16", filled with silicone or Proseal to keep moisture and dust from getting in the cabin area from outside.

On my QB Ifound it just a little difficult to slip the gear weldment socket into place because it bound on a bolt in the center section, but with a little force by hand and a tap with a plastic mallet, it popped into place so I could bolt it on.

CAUTION: Ream or drill the bolt holes to get the powder coat out of the weldment bolt holes BEFORE installing it. :eek: It saves some frustration. I also had a slight misalignment of weldment bolt holes with the center section holes, but a little bit of round filing took care of that problem.

This is m first post of a pic, so I hope it does as I expect... ;) If not, I can send it via regular email if you send your address to me. [email protected] Let me know if you want more.... Glad to help you out!

Don Gray
Cortland, OH
N17QB
 
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