RV-12 Flaperon Pivot Brackets

JimMac · #1 06-19-2012, 08:19 AM

I just finished fabricating the flaperonpivot brackets as directed using a 11/32 drill bit. After tapping with 3/8-24, I screwed in the rod-end bearing and noticed that it is somewhat of a loose fit. Then I noticed on the side of my tap that it said use a 21/64 drill. I'm thinking about remaking the pivot brackets using a 21/64 drill to get a slightly tighter fit. Do you thing this should be done or will the Loctite 243 tighten it up adequately? These threads are the only thing holding the flaperon on the wing.
Thanks

txaviator · #2 06-19-2012, 08:23 AM

I think I'd be re-making them! But that's just my opinion......I wouldn't trust the Loctite in this critical part. Granted, there isn't a big decimal difference between 11/32" and 21/64", but in this instance, it is a HUGE difference (when it comes to tapping / threads).

Smoke Master · #3 06-19-2012, 08:33 AM

Try a "Q" drill for a 75% thread on the aluminum part.
It gives the bearing threads a nice tight fit.

Mitch757 · #4 06-19-2012, 08:41 AM

I had the same problem with mine. I remade the brackets and had a machine shop tap them with a slightly undersized tap to get a nice tight fit.

Mitch Garner
RV4 flying
RV12 under $low construction

rgmwa · #5 06-19-2012, 08:49 AM

I wondered about the slightly loose fit too, but I assume it's acceptable or Vans wouldn't have specified an 11/32 drill.

JimMac · #6 06-19-2012, 09:14 AM

Thanks guys for your responses. I think I'll remake the brackets using a "Q" bit. That should give a nice fit. I just don't like the idea of a loose fit on such a critical part.

MartySantic · #7 06-19-2012, 09:16 PM

Quote:

Originally Posted by JimMac

I just finished fabricating the flaperonpivot brackets as directed using a 11/32 drill bit. After tapping with 3/8-24, I screwed in the rod-end bearing and noticed that it is somewhat of a loose fit. Then I noticed on the side of my tap that it said use a 21/64 drill. I'm thinking about remaking the pivot brackets using a 21/64 drill to get a slightly tighter fit. Do you thing this should be done or will the Loctite 243 tighten it up adequately? These threads are the only thing holding the flaperon on the wing.
Thanks

A very good catch. For those flying, this is one item that should be checked on every pre-flight inspection to ensure there is no free play when pushing and pulling on the flaperon near the two rod end bearing locations.

JimMac · #8 07-12-2012, 12:32 PM

I decided to reorder the extrusion for the pivot brackets and remake them. I had decided that my main problem with the first ones was hand-holding the drill rather than clamping them down and using the drill press. While drilling the holes, I wobbled a little too much and the holes ended up being too large - and also not straight. Well I thought I had ordered a new length of extrusion, but what I got with part number A-1206-AN was a completely manufactured pivot bracket, drilled and tapped and the weight reduction cut made. It was so beautifully done I decided to take the coward's way out and order the other 3 at $6.50 each. The rod-end bearings fit perfectly and I feel a lot better since these threads are all that holds the flaperon to the wing.

yankee-flyer · #9 07-12-2012, 05:40 PM

Anyone consider a little JB Weld instead of Locktite? I'm one of the early builders when Van's was saying to use the 11/32 bit. Yes mine are a bit loose-- will pull the flaperons at the annual and use SOMETHING to take out the wobble.

Given the facts that the down aileron does most of the asymmetric lift generation (upload on the attachments) and down flaps also generate an upload, it looks to me like most of the loads on the attachment are either up or in shear, with very little load trying to pull the flaperons down off the attachment. The wobble, however small, could (will?) enlarge the hole, so I think that needs to be stopped.

Scott, would anyone at Van's like to weigh in on this? Lots of us have been flying with 11/32 holes for a couple of years.

Wayne 120241/143WM

kevinl4000 · #10 01-15-2014, 03:48 PM

My wing kit came with the flaperon pivot brackets pre-cut, pre-drilled, and tapped to spec - I didn't have to fabricate one from AEX or match-drill holes.

My question is whether the Loctite 243 called for in the plans is still necessary, since (1) the bracket that mounts on the wing rib prevents the rod-end bearing from turning, and (2) the rod-end bearing threads are snug in the pivot bracket threads?