elevator flutter

[jgerard]

I was climbing out from one of the local mountain strips last weekend and noticed a slight flutter from the elevator. The yoke was moving in and out almost 1/2" at about a 120 spm (strokes per minute???) . I reduced power, flattened the climb and the shaking went away. This is the first time I have noticed any flutter. I have done a lot of slow flight and unusual attitude flying in my plane and never felt anything before. After landing I inspected the trim tab which has just as much slop as all the other T-carts I've looked at, but I did notice the control horn on the trim tab is kind loose, like the rib it's attached to may be broken. I will head back out and test fly her some more tonight and try to recreate the flutter with a chase plane watching the tail so I can get a better idea of what's going on.

Any ideas guys?

Jason
N43643

[stormman]

Climbing out or stalling out? Seems i had that feeling once a long time ago, or maybe it was a dream!

[jgerard]

climbing out at 60mph.

Jason
N43643

[Pearson]

Flutter

Jason

Sorry I missed your soire this past weekend. I look foward to the next one.

Before you fly again you may want to check the forward attach bolts on the horizontal stabilizer. I have seen the holes get elongated. You can check this on preflight by trying to move the ends of the stabilizer fore and aft. I doubt this is the cause of your flutter, but I would certainly want to eliminate it early in the search.

Regarding the loose trim tab, I would apply a gentle upward and then downward pressure on it while watching the suspected broken area of the elevator. If something really is broke in there, it seems like you would see a bulge in the fabric when you applied pressure on the trim tab. Also can you possibly get a mirror up into the inspection hole?

I assume your tail brace wires are all straight and of the right tension? I would try to do everything I could to check this out before I went flying rather than playing test pilot.

Cheers,

[jgerard]

My right fwd stab attach bolt hole is a bit wallowed out, the right stab does move a bit but no worse than any Cub that I've flown. The flying wires are in good condition, just replaced the lower ones and I checked them out after landing, their fine. What I felt was the elevator fluttering up and down that's why I suspect the trim tab to be at fault. I think Forrest said the factory test flew these birds with the tab pushrod disconnected and had no major problems.

Don't worry folks, I have been the test pilot many times before. I will let ya'll know what I find if I can recreate the flutter.

Jason
N43643

[Forrest Barber]

tighten up the trim system. We flew her tab free for testing; BUT with the rods hooked up and the tab getting excited and you feel movement I would fix it....... Is it possible the tab is heavier at the trailing edge ( water, dirt , hidden money) . ??