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Gentlemen, check your flaperons!

This was discussed in another thread some time ago ... VANS cleared us and another if i recall to use CS4-4 on the rear spar doubler to help alleviate the issue.
 
This was discussed before. I had a slight case of contact, and simply trimmed the lower edge of flaperon skin, smoothed it with scocthbrite, and touched up the edge with paint. Problem gone.
Dick Seiders
 
dick seiders said:
This was discussed before. I had a slight case of contact, and simply trimmed the lower edge of flaperon skin, smoothed it with scocthbrite, and touched up the edge with paint. Problem gone.
Dick Seiders
Click to expand...

I made a search before posting but did not find specific and/or documented enough posting on the subject to deem my own posting unnecessary. What shocked me is that Kim had just completed his one year inspection which had no instruction to look at this potential problem. I suspect that many flying RV-12 have the same damaged rivets without their owner knowing it. Although it's not a life threatening issue, I think that VANs should do something about it.
 
+++DONT BE CONFUSED - this issue is NOT about the inboard flaperon "skin" rubbing against a fuselage side rivet!+++

My rivets also touch. Seems to be only enough to take off the paint but I only have 20 hours. Note that because they touch, this limits flaperon travel. This is an interesting problem for several reasons.

(Now, it does look like drilling out/replacing one LP4-4 rivet with a CS4-4 rivet will solve the issue. Requires pulling the wings out a couple of inches and maybe taking off the flaperons to get at it. FYI this is the rivet on page 14-03, bottom-most outboard rivet attaching the W-1212 hinge assembly on either wing. Noted as "leave open" on this page, later riveted on page 15-06 using LP4-4.)

But...

Remember in the PAP how you check for PITCH travel limits. You are supposed to hit the limit on the tail just before you hit the limit on the stick. I've seen mention of checking with a piece of paper as a feeler gauge up at the stick end and did that.
But what about the roll limits?

On page 32-10 you are match-drilling the flaperon torque tubes with the flaperons in their neutral position. Then you take the wings off and finish up the flight controls. You later reattach the wings in Section 33 but there are no instructions about checking flaperon travel there. Nor in any later section of the plans! (And no relevant revisions posted about Section 32.)

When you get to the Production Acceptance Procedures (PAPs) Section G2, you do several full range move-the-stick-around tests. This rivet interference could define your limit of flaperon deflection with flaps up. You would not "feel" it as interference. You measure some distances about the anti servo tab and the rudder. But you never measure anything about the amount the flaperon moves up or down compared to, say the wingtip skin. That is all controlled by carefully making the pushrods to specified lengths on page 32-05 and -06.

So this rivet interference, until fixed, is perhaps defining the flaperon max upward travel. (What DOES/SHOULD define that? My memory and drawings are not making that clear and I don't want to start removing cover plates to see.)

My kit is #412 and I don't see any relevant revisions to Section 32 or 15. My PAPs are Revision 1.

What say you experienced folks?????? I tried but could not find this in a prior thread.
 
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Old problem

There's a long thread on this someplace as quite a few of us had this problem. I found that I couldn't really feel any drag or interference with the stick but if I moved the flaperons by hand I could feel them "stick" at one end (up??? I don't remember) of the travel. I put dabs of paint on the ends of a half-dozen inboard rivets, moved the flaperons. and that showed me which ones were touching the spar. I drilled those out and replaced them with CS rivets-- don't forget to countersink holes for them! This was before Van's apparently OK'd the process (#55 to fly) but that seemed better to me than potentially have a flaperon stick or to damage a rivet head.

Wayne 120241/143WM
 
Bill_H said:
+++DONT BE CONFUSED - this issue is NOT about the inboard flaperon "skin" rubbing against a fuselage side rivet!+++

My rivets also touch. Seems to be only enough to take off the paint but I only have 20 hours. Note that because they touch, this limits flaperon travel. This is an interesting problem for several reasons.

(Now, it does look like drilling out/replacing one LP4-4 rivet with a CS4-4 rivet will solve the issue. Requires pulling the wings out a couple of inches and maybe taking off the flaperons to get at it. FYI this is the rivet on page 14-03, bottom-most outboard rivet attaching the W-1212 hinge assembly on either wing. Noted as "leave open" on this page, later riveted on page 15-06 using LP4-4.)

But...

Remember in the PAP how you check for PITCH travel limits. You are supposed to hit the limit on the tail just before you hit the limit on the stick. I've seen mention of checking with a piece of paper as a feeler gauge up at the stick end and did that.
But what about the roll limits?

On page 32-10 you are match-drilling the flaperon torque tubes with the flaperons in their neutral position. Then you take the wings off and finish up the flight controls. You later reattach the wings in Section 33 but there are no instructions about checking flaperon travel there. Nor in any later section of the plans! (And no relevant revisions posted about Section 32.)

When you get to the Production Acceptance Procedures (PAPs) Section G2, you do several full range move-the-stick-around tests. This rivet interference could define your limit of flaperon deflection with flaps up. You would not "feel" it as interference. You measure some distances about the anti servo tab and the rudder. But you never measure anything about the amount the flaperon moves up or down compared to, say the wingtip skin. That is all controlled by carefully making the pushrods to specified lengths on page 32-05 and -06.

So this rivet interference, until fixed, is perhaps defining the flaperon max upward travel. (What DOES/SHOULD define that? My memory and drawings are not making that clear and I don't want to start removing cover plates to see.)

My kit is #412 and I don't see any relevant revisions to Section 32 or 15. My PAPs are Revision 1.

What say you experienced folks?????? I tried but could not find this in a prior thread.
Click to expand...

Thank you Bill, your wrap up is most helpful. This confirms my belief that this issue is sufficiently widespread to justify an action by VANS in the building instructions and a recommendation to inspect the flying airplanes. I have contacted VANS and am waiting for an answer.
 
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Today I replaced the one touching rivet on each flaperon with a CS4-4. I had the wings all the way off anyway to install the wing root seals.

I found that (before the fix) with the wing OFF and flaperon still attached, I could move the flaperon enough to make the rivets pass each other and "jam" - requiring too much force for comfort to "pop back" the other way. But with the wing on this couldn't happen (in my case) - I think the left-right stick movement is hitting its stops in the tunnel before that amount of flaperon deflection. But it is pretty close...

To do the fix, you only have to pull the wings out far enough to pull out the flaperon linkage, then remove the flaperons, to remove the LP4-4 rivet and countersink and pull the CS-4.4 on the wing rear spar.
 
Bill_H said:
Today I replaced the one touching rivet on each flaperon with a CS4-4. I had the wings all the way off anyway to install the wing root seals.

I found that (before the fix) with the wing OFF and flaperon still attached, I could move the flaperon enough to make the rivets pass each other and "jam" - requiring too much force for comfort to "pop back" the other way. But with the wing on this couldn't happen (in my case) - I think the left-right stick movement is hitting its stops in the tunnel before that amount of flaperon deflection. But it is pretty close...

To do the fix, you only have to pull the wings out far enough to pull out the flaperon linkage, then remove the flaperons, to remove the LP4-4 rivet and countersink and pull the CS-4.4 on the wing rear spar.
Click to expand...

I guess the CS-4.4 is the solution, I was just concerned about countersinking the skin as in this case the normal way to go would be dimpling which of course is not possible. From your experience is there still some skin left under the rivet head? How deep did you countersink?
 
The removed lp4-4 rivet and countersinking is on the W-1212 hinge bracket, not the skin on the flaperon. I left that rivet alone. The wing bracket is thick and takes the countersink.
 
Bill_H said:
The removed lp4-4 rivet and countersinking is on the W-1212 hinge bracket, not the skin on the flaperon. I left that rivet alone. The wing bracket is thick and takes the countersink.
Click to expand...

Good point Bill, I was afraid that only one CS4-4 would not be enough clearance, thanks for letting us know!
 
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