Wing bolt alignment issue on -9A

JVolkober · #1 02-21-2012, 10:12 AM

Well I'm down to getting the wings on. Had them on a couple of years ago with the fuselage on saw horses to set wing incidence using hardware store bolts with no issues. Now I've got the right wing on, top 7/16" bolts in place and find that the lower holes in the gear weldment out as up to 1/6" out of alignment with the spar box and spar. The weldment holes are offset toward the side of the fuselage. Has anybody experienced this issue. My guess, and Vans, is that the weight of the fuselage with engine on the gear is the cause.

John

Bob Axsom · #2 02-21-2012, 10:38 AM

I supported the fuselage and wings on special horses that I made to relieve stresses you can put a engine hoist on the engine to relieve that stress. I stood the fuselage horses on a 4'X8' panel of high quality 3/4" thick plywood with sisor jacks reasonably near the four corners of the plywood and precisely leveled the canopy deck whis the master reference plane for our RV-6A. What ever you do don't enlarge those holes if you have already had the right sized hardware in the properly aligned holes. I had the wings on our RV-6A at home and I had to take them back off to allow my wife to put her car in the garage and to move the airplane to Chino for final assembly. It took 2 or 3 days to get the bolts in - keep working with it.

Bob Axsom

rv9av8tr · #3 02-21-2012, 10:58 AM

Knowing that the bolt alignment to the centersection is fixed, I'd suggest loosing the gear leg weldment bolts to allow the weldment a little wiggle room for the bolts to enter the weldment. Once all the wing bolts are through, then resecure weldment bolts.

CAUTION here, don't work the bottom spar bolts all the way in because there isn't room to start the nuts! Don't ask how I know!! You have to get only a couple threads through to get the large nuts started, then you can draw the bolts up tight. I had to grind down an open end wrench to fit behind the weldment on those bottom bolts.

Use some lubricant on the bolt shafts, these are EXTREMELY tight! I swore I'd cut the wings off before I'd ever try taking these bolts back out, once in!!
It will take hours of scraped knuckles, be patient and just keeping working at it.

Jeff R · #4 02-21-2012, 06:05 PM

Maybe take the top bolts out and put the bottom ones in first. Dealing with the bottom bolts is one huge, frustrating pain in the butt. If you can get the bottom ones in, the top ones will be easier to deal with.

frazitl · #5 02-21-2012, 06:16 PM

on my 7A. Ended up filing the weldment (ONLY) to get those bottom bolts in. I used rat tail files with duct tape on most of the file to protect the aluminum spar and spar carry through. Took a bit, but I didn't have to start over. Mouse Milk oil helped me get the close tolerance bolts in.

JVolkober · #6 03-15-2012, 10:58 AM

The solution to the problem was to take the weight off the plane by using an engine hoist to lift the fuselage at the engine mount with it supported at the tail cone. All the gear weldment attachment bolts were loosened but not removed to allow the weldment to float as much as possible. This removed most of the miss-alignment of the lower weldment holes to the spar and spare box. The remaining adjustment was done using a tapper pin created by grinding down a 7/16"hardware store bolt. With the tapper pin in place, the lower 7/16" bolts were tapped into place using a rivet gun. Interference of wiring limited the use of a mallet.

From my experience, I would recommend getting nuts on and tighten on the outer most 1/4" bolt first and then working towards the center of the plane. Clearances and options for getting nuts on and applying wrenches are very limited if the nut on the inside 7/16" bolt is in place. Likewise, if the nut on the outside 7/16" bolt is in place, it is very awkward to get the nut started on the outside 1/4" bolt.