flaperons stiff

[darrellpralle]

first flight 7/24, now have 20 hrs. The flaperons seem to be too stiff. everything was fine before I hooked the push-pull rods to the flaperons. I have lubed the bushings with dry lube, helped a little. any suggestions will be appreciated. it is a ss. thanks

[Dave S]

Hi Darrell,

First off, congrats on the first flight and great start on your phase I.

Sounds like you have a little bit of a troubleshooting deal ahead of you on the stiff flaprons. Frankly, I find that the rod end/push pull tube system of the Kitfox is extremely low friction....shouldn't be stiff at all.

I'll toss out a couple ideas....don't know for sure what is causing the issue.

You mentioned that before the push pull rods were installed, the flaperons were not like this. What happens if you disconnect them now? do they rotate freely again?

Does the stiffness occur both in flight and on the ground?

Wondering if there is some friction in the rest of the alieron control system somewhere? In other words, with the flaperon rods disconnected, what happens when you sit in the cabin and work the control stick? Parts of the underseat mechanism for the alieron action run pretty close to other parts....any chance the seat deforms slightly causing contact with controls?

Let us know how this issue resolves...I don't think it is very common to have the flaperons exhibit any stiffness at all.

Good luck,
Sincerely,

Dave S
KF 7 Trigear (Flying)
912ULS Warp Drive
St Paul, MN

[akarmy]

I too had stiff flaperons. Found two things. First the tube under the seat was flipped 180deg which caused the bend in it to just rub on the seat pan when you sat in the plane, giving lots of friction. Once that was fixed, The zero point on the flaperons needed to be adjusted. If they are drooping a little they will have aerodynamic drag on them in flight causing a heavy feel even when they seem free moving on the ground. That was fixed by re-rigging everything to zero degrees.

[Av8r3400]

Also check the seat pan for cracking. Mine had sagged and was rubbing on the pushrod. There's a thread here somewhere about putting a block of wood under the seat to prevent collapsing.

[darrellpralle]

went out to plane this am, disconnected push-pull tubes. stick is very free with tubes disconnected. binding seems to be in the flaperon bushings. lubed all bushings with dry-lube again, seemed to help some, but still feels to stiff. thanks for your help. N765DP

[Dave S]

Darrell,

If the stiffness is truly in the flaperon bearings, I think you are likely down to two or three possibilities....1) the bearing brackets/bearings possibly misaligned, 2) the surfaces between the spar and bearings possibly gummed up with foreign material or goo of some kind that may have gotten in there, 3) The plastic bushings potentially exposed to something that either melted them somewhat or soaked in and swelled them.

FWIW.....on my flaperons I can grab the flaperon at each bearing hangar and detect a small amount of play between the bushings and flaperon spar tube...also some detectable end play on each flaperon.

Good Luck with resolving this....:confused:

Sincerely,

Dave S
KF7 Trigear
912ULS Warp Drive

St Paul, MN

[jdmcbean]

Darrell,
Please contact me direct...

[darrellpralle]

the binding was due to misalignment of one of the brackets on each side. by disconnecting all brackets except the inner and outer, then reconnecting them one at a time I determined which one was binding. a slight enlarging of the mounting holes cured the problem.

[Spook712]

the binding was due to misalignment of one of the brackets on each side. by disconnecting all brackets except the inner and outer, then reconnecting them one at a time I determined which one was binding. a slight enlarging of the mounting holes cured the problem.

What brackets? Can you post a picture ?

[JohnB]

I was prepping my flaperons for mounting to the wings today and discovered that I have one flaperon bushing on each flaperon that is very stiff. All the other bushings are very free. The flaperons have been stored in a clean dry place with no chance of contamination.

I tried lubing them with the recommended LPS-1 and working them through a few hundred cycles but not much improvement.

Has anyone else experienced this, and if so, did you find a solution?

[SkyPirate]

I wonder if wet sanding the ID with some 1500 grit paper would fix it

[JohnB]

I wonder if wet sanding the ID with some 1500 grit paper would fix it

That would work for the bushings at the control horn end, but the ones that are stiff are in the middle of the flaperon. It looks to me like these are not removable and the only access to them is thru the slots that the hinges stick through.

[darrellpralle]

there are two bolts connecting the wing rib brackets to the flaperons

[colospace]

JohnB,
I too, in preparation for locating the flaperon brackets, have found that one of my outboard hinges is very stiff rotating on the flaperon spar. Did you ever get resolution to your hinge stiffness?

[JohnB]

Gary,
I just lubed them repeatedly with LPS-1 and kept working them and they seem to have loosened up somewhat. Still not as loose as the others though.
The good news is that when I had them connected to the controls to do the rigging, I didn't really notice any friction or stiffness through the control stick.

Good luck with yours.

[colospace]

Thanks John, I'll just keep working with it. At least there is only one that is stiff. The others all move very freely.