Oscillation of stab on my AW 100cc Extra-Has anyone else ever seen this???
05-10-2015, 06:32 PM
#1
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Oscillation of stab on my AW 100cc Extra-Has anyone else ever seen this???
AW 100cc Extra with DA100 with stock mufflers. Hitec 7955s on the elevators. Doing a low fly by at high throttle straight and level, a friend at the field yelled that the stab was "bouncing like it was on a trampoline". Flew it by again the same way and noticed that the whole stab, not just the elevators, was shaking like I had never seen before. Landed and checked the linkages. Everything was tight and I could find no play anywhere. This is really worrying me,I know what flutter can do to an airframe, and even though this isn't an elevator fluttering, something is causing the entire stab assembly to bounce and that shouldn't be happening. I wondered if anyone else has ever had this happen? If anyone has, what is the fix for it? Thanks
05-11-2015, 08:21 AM
#2
Senior Member
This probably has a plug in stab. Check to make sure that the tube is very snug in the fuse. If the tube is a sliding fit only, then it may not be snug enough. I'd suggest that you epoxy a strip of fiberglass at the center and refit it into the fuse to a snug fit.
Check to make sure the stab halves slide very snug on the tube. If loose, then extend the glassing to the sections that are in the stab halves. Chances are the stab loosenes will only take one layer of 3/4-1 ounce cloth and sanding to fit snug.
The stab construction may not stiff enough. Grab the stab half at root and tip and try twisting. You should get a lot of resistance. If not then the stab needs to be replaced. Ask the factory for a new set and re-fit it carefully.
Also check the securing hardware. If not robust enough or give your stab play, even small play will magnify at speed. The socket may not be glued well enough inside the stab.
If everything checks out, about the only other solution available is to remove the tube and hardware and mount the stab into the fuse the old fashioned way.
Check to make sure the stab halves slide very snug on the tube. If loose, then extend the glassing to the sections that are in the stab halves. Chances are the stab loosenes will only take one layer of 3/4-1 ounce cloth and sanding to fit snug.
The stab construction may not stiff enough. Grab the stab half at root and tip and try twisting. You should get a lot of resistance. If not then the stab needs to be replaced. Ask the factory for a new set and re-fit it carefully.
Also check the securing hardware. If not robust enough or give your stab play, even small play will magnify at speed. The socket may not be glued well enough inside the stab.
If everything checks out, about the only other solution available is to remove the tube and hardware and mount the stab into the fuse the old fashioned way.
