My wings began flapping - scary - what was it?

[Peteohms]

I have a Kitfox 3 and have about 660 hours flying it. I have never experienced any wing flutter. I cruise about 90 mph.

[jdmcbean]

Flutter is a VERY serious issue and should never be discounted.

Do not confuse flutter with the wing flex. The Kitfox wing does flex.. so does a 787 wing.

The model 1 through 3 controls are very different than the Model IV through current.

Prior to your next flight follow the suggestions previously stated and start with all the control connections for correctness and tightness. You should not have any that are loose especially in the Rod-Ends.

Sounds like the wings were flexing with the thermal activity and this was the first experience for you.

[Micro Mong Bldr]

Well, I did find one slightly loose joint in the control system, bearings at the inboard ends of the flaperons look fine. Really don't know what else to try. Thanks for all the help. Maybe I'm just not used to the flexibility of the outer wing panels.
Cheers,
Larry

[Micro Mong Bldr]

Took it up again yesterday - got some flapping on climb out, again on final. Both times it quit with just a bit of aileron input. The outer wing panels on these things seem quite flexy - when you hit a bump do they tend to go through a number of cycles before damping out? Am I just over reacting to something normal? I'd guess frequency about 1/2 second, not a whole lot of movement maybe 4 - 6 inches...

The only thing "different" I've done is lube all the control pivot & bushings points with synthetic oil, which tends to be slicker, so when I got down I put WD-40 on all the aileron bushings, as that dries to something a bit thicker, "greasier". Suggestions?

Cheers,

Larry

[Peteohms]

Maybe some of your wing ribs came loose from the spars.

[Micro Mong Bldr]

Ribs loose - hmmm - it seems to be straight up and down, not a twist, I think.....not 100% sure. If I grab ahold and wriggle the wings U/D & all at the tip during preflight, I don't notice any looseness anywhere, maybe I need to try and wriggle each rib U/D at the trailing edge?

Thanks,

Larry

[Micro Mong Bldr]

Well, I've worked on all the linkages & removed play, new tight fitting turtledeck bushings - I still get it. Not the classic high speed flutter - slow & with lower RPMs - got it on short final only about 10' off the ground, seems to be correlated with low 3000's RPM. It has a HKS, 2 blade IVO, the lower reduction ratio (2.47:1?). Thoughts?

Thanks,

Larry