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Heavy Wing Developed

BamBam-4

Member
I have owned my RV-4 for about 2 years and approx 400 hours now. The airplane now has around 1500 hours TT. The airplane had always flown great, very straight. A couple months ago I developed a heavy right wing. At 150-155kts IAS if I release the stick it will make a sharp departure to the right. At slower speeds, around 100kts IAS it is still noticeable, and at approach speeds it is much less, barely noticeable. My friends who are builders have told me to install an aileron trim tab, but that doesn’t seem right to me as the airplane always flew straight before. I don’t remember any hard or heavy landings that would’ve damaged anything. I’ve looked under the belly and down the wings, I see no buckled panels or indications of damage. The firewall does not appear damaged. Is there something you could recommend for me to check?

I had this issue once before and found that a screw on the top fairing around the stabilizer had come lose allowing the fairing to pull away from the aircraft. I tightened the screw and things went back to normal, nice and straight. I had hoped this was the issue again, but it was not unfortunately.

Thanks in advance for any suggestions.

R/

Wesley
 
If the airplane flew straight before, I wouldn't make any adjustments until I found the cause for the change. Look back just prior to the problem and see if you did anything to the airplane.
 
A common cause of heavy wing is an aileron that is higher or lower than it should be, in the vertical plane, on one side or the other. I would check for a failing bearing in the aileron attach brackets, allowing up or down movement of the aileron.

Also look for symmetry of the flaps, relative to the alierons while flying. Possibly a loose connection in the flap attach H/W.

Larry
 
A common cause of heavy wing is an aileron that is higher or lower than it should be, in the vertical plane, on one side or the other. I would check for a failing bearing in the aileron attach brackets, allowing up or down movement of the aileron.

Also look for symmetry of the flaps, relative to the alierons while flying. Possibly a loose connection in the flap attach H/W.

Larry

Thanks Larry, I’ll have a look at both of those right now and report back.
 
I checked the ailerons, they seem right, no play. The flaps however have about a 1/2 to 3/4 inch of play up and down. That did trigger a memory, my flap down switch is at the back of the stick and I have bumped the flaps down at cruise speed more than once. How much slack do RV’s normally have in the flaps?
 
I doubt seriously that the flaps are the problem. They are so far inboard that they have little effect on roll. However, wheel pants, yes, they can have a real effect. My -6 flew straight for many years. When I changed over to the "Dolly Parton" wheel pants, I needed a trim tab. I double checked and found the new pants were indeed straight. Possibly the original pants exactly straight.
 
a few more random ideas

Check rudder bearings and fairings fairings for fit/damage.

Check for insect or animal nests, or trapped water inside the right wing/flap/aileron.
 
I doubt seriously that the flaps are the problem. They are so far inboard that they have little effect on roll. However, wheel pants, yes, they can have a real effect. My -6 flew straight for many years. When I changed over to the "Dolly Parton" wheel pants, I needed a trim tab. I double checked and found the new pants were indeed straight. Possibly the original pants exactly straight.

Thanks Mel. I’ve never changed the wheel pants, just removed and replaced to bleed brakes and check tire pressure. Could the same wheel pants make that difference? If so, how do I check that. They seem aligned to the naked eye.
 
Some people think that reshaping the trailing edge doesn't do anything to adjust roll trim but I know of RV owners that have flown to a fly in and while there, someone must have squeezed a trailing edge while "poking" around their airplane. Flying home they had a heavy wing that wasn't there before.

After finding the location on the aileron and correcting it, Heavy wing was gone.

Even a big blob or bird poop in the wrong place on an aileron can do strange things.

Same suggestion as Mel... look for something that different from when it was in trim.
 
Update: Flew the airplane without wheel pants and it still had the heavy wing. I’ll look over the ailerons and see if there is any damage or crimping.
 
I know for a fact that squeezing the trailing edge can cause a heavy wing, or in my case, resolved the heavy wing. So...if trailing edge was pinched or bumped against something, this could cause a heavy wing. We’re talking ailerons here.

Some people think that reshaping the trailing edge doesn't do anything to adjust roll trim but I know of RV owners that have flown to a fly in and while there, someone must have squeezed a trailing edge while "poking" around their airplane. Flying home they had a heavy wing that wasn't there before.

After finding the location on the aileron and correcting it, Heavy wing was gone.

Even a big blob or bird poop in the wrong place on an aileron can do strange things.

Same suggestion as Mel... look for something that different from when it was in trim.
 
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After inspecting the ailerons I see the left aileron has a crimp starting 2” outside the aileron root, after the connecting rod, and the crimp is 10” long. Would that give it a left roll or right roll tendency?
 
After inspecting the ailerons I see the left aileron has a crimp starting 2” outside the aileron root, after the connecting rod, and the crimp is 10” long. Would that give it a left roll or right roll tendency?

Crimping aileron trailing edge causes the aileron to "fly up", which would cause that wing to "fly down". So crimping the left aileron would cause a left rolling tendency.
 
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I’ll second Rvbuilder2002, it takes very little changes to the aileron to make a big difference.
I originally had a heavy wing and fixed it by very slightly squeezing the aileron. Fast forward several years and I was polishing small sections of the plane. I had just polished the bottom side of one aileron and did a flight the next day, I again had a heavy wing. Apparently the force of polishing the aileron was enough to change he airflow around the aileron. I polished the underneath of the opposite aileron and that fixed the heavy wing again. It doesn’t take much.
 
Wesley, if you bumped the flap switch at cruise speed, check to make sure flap rod isn’t bent.
 
That puts me back to square one I guess. My rolling tendency is to the right, the crimped aileron is the left. Seems the original builder prob did that to correct a right roll tendency already. Is it possible that I need to re-crimp it for some reason?

Tracy:

I had wondered about that, so I pulled both rods, and to the naked eye, neither is bent. 🤷🏼*♂️
 
A common way to adjust a heavy wing is to lower that aileron by ovaling the aileron hinges attach holes to lower the ailerons vertical position. If that had been done and the hinge bolts loosened up, letting the aileron slide up, you would see that wing become heavy again.
 
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A common way to adjust a heavy wing is to lower that aileron by ovaling the aileron hinges attach holes to lower the ailerons vertical position. If that had been done and the hinge bolts loosened up, letting the aileron slide up, you would see that wing become heavy again.

Really? I do not think that would be considered an acceptable fix. Kind of scary to me.
 
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Welding rod

Check (or remember) to see if there was a piece of welding rod taped to the bottom TE of the left aileron. If there was one, and it’s now missing, that would cause a right roll change. If not, that’s an easy way to adjust roll trim
BB
 
BamBam-

One possible area that has not been mentioned yet is the cantilevered wing skin aft of the rear spar. Use a straight edge starting at a wing rib and make sure the skin aft of each wing's rear spar is on the same plane as the wing skin forward of the rear spar ... tweak as necessary and slowly make your way across the wing. Below is a link to a photo showing the aft area a little too high on my bird ... looking closely at the photo, you can see a small gap under the straight edge.
https://3.bp.blogspot.com/-YDIzWxpT_ns/WCSLfxfH8jI/AAAAAAAAMgk/mRntXdS_MSsjWvBJrpmRbq2cyQzMzGthACLcB/s1600/DSC02429.JPG

My bird had a slightly heavy left wing after construction was completed ... and, in my case, there were areas aft of the rear spar that were not on the same plane as the wing skin forward of the rear spar ... some places were a little high and others a little low on each wing. I used a small block of wood and tweaked every few inches to get that area as straight as possible.

That fixed the heavy wing .... until I got the bird painted. Apparently just the pressure from sanding the skin was enough to bring back the heavy wing (but not as bad) so I needed to tweak the area aft of the rear spar once again to obtain hands off level flight.

I'm guessing it is possible just a little too much pressure during washing or waxing could have moved the wing skin just enough to be noticeable. This may not be your issue ... but easy enough to verify.

Happy flying,
 
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A common way to adjust a heavy wing is to lower that aileron by ovaling the aileron hinges attach holes to lower the ailerons vertical position. If that had been done and the hinge bolts loosened up, letting the aileron slide up, you would see that wing become heavy again.

Making oval holes on flight controlls or any other thing on an aircraft is not acceptable :eek:
 
The engine was certified like that and an alt bracket isn’t primary structure. A lose belt and a flight surface that could move in a slot/change aero/induce flutter are very different. I’m positive you already knew that and were making a point about “absolute” type statements.
 
I've seen the slotted aileron hinge process discussed on here quite a few times as a method of correcting an aileron that's mis-located vertically.

The caveat is that it's a flight test item for a short period of time, and once you understand what the correct position should be, the follow up is to order new undrilled hinges from Vans and locate proper holes in the proper position.

100% agree that it would be a horrible practice to leave them slotted over the long haul, but you could certainly see a scenario where it might have happened, and in this case be worth investigating, especially if the OP didn't build his airplane
 
Last night we checked the incidence of the wing at the root and out towards the tip of the wing. Right wing had 8.8 degrees at tip, 8.7 on the root. Left wing had 8.7 at the tip and 8.6 at the root. At most, .2 degree split across both wings. I flew to breakfast this morning and noticed that if I bumped my flaps down about 3/4 “ or so the air raft quickly came back straight and level with no pressure. Why would that be?

Thanks for all of your replies everyone!
 
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