RV-10 Gear weldmount align issues

Hey All,

Need advice, having issues lining up my bolt holes on my left gear weldmount onto my fwd center section of my rv-10. I sent both gears mounts back to vans and they said they were ok. I think my left one was welded slightly out of alignment from the jig, so Im trying to make them work. I have an old fwd center section and I had to use SB-0007 template to drill it. All bolts slide thru template and bushing with very little resistance so my drilling was good. When i first noticed the problem was in section 25-3 step 1 when they tell you to temporarily mount the landing gear mount so you can trim the flange on the bulkhead to accept the gear tube. Since I had not drilled it yet I used the factory available bolt holes to mount it, which was the top 8--an3 bolts and the two-- an3 bolts that are in the leg that is welded to the mount. Thats when I noticed the problem, those two bolts on the leg were about a 1/16 or more off center and I could not slide the bolts in. Also, all the rivet relief holes need to be opened so not interfere with the rivets. I was able to force it on by putting all the bolts in the mount holes and then putting them in the fwd center section holes and forcing them down, and I mean force!! I had to hammer some of the bolts in, so it was under a lot of pressure, but it was on. My next coarse of action will be to relieve some holes. Any suggestions on what to do? Should I relieve smaller holes versus larger ones and I was thinking to relieve the steel on the gear mount not the 1" aluminum on the center section.

Thanks

Have you checked interference between the tube and the flange of the center section? I had to trim the flange of the center section so the gear mount would sit flush. If the tube is pushed up by the flange even by a tiny amount the mount will be crooked and the holes won’t line up.


Alex

Checked Gap

Yes I checked it numerous times. I bent a small tie wrap at a right angle and made sure it passed all around under the tube


Thanks

Pictures.

Here’s some pictures

I recall the fit being pretty tight on mine. I had actually contacted Van’s support and they assured me that using a hammer to get the fit was fine. They suggested (and I’ve heard it here elsewhere) using a bolt with the threads filed off as a guide bolt. You can then bolt the other holes. It is a pretty tight fit, but with some careful persuasion mine came together. You can also use Boelube if you’re careful to keep it off the threads. I would be very reticent to relieve any holes on the mounts or the spar without talking to Van’s support.

Alignment

dpz said:

Here’s some pictures

Click to expand...

From my experience on nose gear aircraft welded items that is about as close as you can expect. Actually looks fine to me but maybe pic don't paint the whole picture?

In your pic it sure looks like the whole weldment needs to rotate CCW a bit.

Have you checked that the drill template lines up with the weldment? That'll let you know if your weldment was drilled incorrectly.

On my center section, the original holes were actually drilled crooked on one side and the drill template for the revised mounts fixed it. I used a pilot point drill to keep it from wondering.

I also had to taper and open up the notch in the rivet flange in the center section quite a lot to allow the weld to clear without interference. It's an iterative process but my weldments fit the center section without much drama now. Even small amounts of interference can prevent the weldment from seating on the center section correctly.

Template alignment

Thanks for the replies..I did try to bolt the template to the weldmount and the right gear weldmount went on with very little resistance but the left one I could not get to line up with the holes in the template . That’s why I believe the left one is not welded correctly but Vans tells me it’s fine. I want to relieve some of the holes because when I torque the nuts I don’t think they will pull the bolt through the holes of the weldmount to a flush fit since they are under so much pressure. I think the pressure on the bolts due to the misalignment is greater then the torque that will exerted. This is only my opinion since I have not actually tried to torque any nuts. I will have to take away about 1/16 of an inch from all the rivet relief holes to get a flush fit. The person at vans had two statements , 1–“It is not that critical 2– “ It seems you achieved what the plans instructed you to do, put the bolts thru the holes”..

Thank Again for your help

Rule #1 of assembly

Rule #1 - always file, bang or bend the cheapest & easiest part to replace, --- fewer regrets.
Rule #1 and 1/2 - sometimes try using a longer bolt(s) to 'fit' the part and then don't forget to change it for the proper fastener before torquing.
Rule #1 and 3/4 - using a std AN- bolt instead of a close tolerance bolt for initial assembly can sometimes solve and sometimes frustrate getting the close tolerance fastener installed. This also applies to using drift pins (bolts with threads ground off, inserted with percussive tools).
Rule #1 and 7/8 - don't start tightening fasteners until all of them are inserted and nuts are finger tightened. Let it float a little.
Stop, go take a break, work on something else, give it overnight to think about. If it feels too frustrating, accomplish sometime else first.
Is it 'close enough for government work' yet?
I've never personally regretted any of my learning experiences, almost never.