What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-12 Flaperon Pivot Brackets

J

JimMac

Active Member
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
 
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).
 
Last edited:
Pivot Brackets

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

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.
 
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.
 
JB Weld?

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
 
Loctite on flaperon pivot brackets question

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. :p 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?
 
I think the 21/64 is the best choice

I think the 21/64 is the best choice, about 78% thread and the Q drill is about .0039 smaller and is about 71% thread
My view



Smoke Master said:
Try a "Q" drill for a 75% thread on the aluminum part.
It gives the bearing threads a nice tight fit.
Click to expand...
 
Normaly rod end bearings also have a jam nut. These take up the slack between the threads and firm up the rod bearing. If you do not use the Loctite, the bearing can vibrate and/or move ever slow slightly on the threads causing premature wear. Like was said before, it can't hurt to use it.
 
Last edited:
Thread locker is still recommended (that is why it's still in the KAI).
There really is no down side to using it (other than having to purchase some and you will use it for other things). If the proper thread locker is used, it is still relatively easy to remove the rod ends if they would ever need to be.
 
JimMac said:
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
Click to expand...

I too re-made the brackets using a 21/64 drill about one year ago. How quickly we forget. Tonight I drilled and tapped the aluminum AP push rod for the rod end bearing. Same issue. Slight wobble wobble. Probably not an issue since the jam nuts should tighten the bolts to prevent any movement.
 
Adjusting rod bearning height

What I've had to do (and from reading on here, many others as well) has been to make adjustments to the height of these rod bearings to address a heavy left or right wing that is only observed during flight testing. I used Loctite as the KAI instructed during the build, but after making some fine adjustments to the rod bearings to better balance my flapperons, its not sticking any longer and I don't want to unscrew the all the bearings and reapply as I just got the heights all where I want them.

So use Loctite during the build, but chances are you'll need to rotate some of these rods after you begin flying:eek:.
 
You must log in or register to reply here.
Back
Top