That Pesky Fabric Drumming Wing Root.

[McDaver63]

59pacer, OK Thanks for your description of your foam fix. I will consider doing that. I did experiment with placing a section of foam about 5/8" thick between the aft spar and the fabric fwd of the inspection plate. Took up for a test flight and it did reduce the drumming at the inspection plate area quite a bit. Still could see the drumming fwd of the spar but it also seemed reduced.

[cjutzi]

for me, I glued some felt along the spar to close the gap between the fabric and the rib. This kept the fabric from bouncing on climb and I have had no issues for 2 years so far..

[Subsonic]

Had to repair the wing root butt rib - right side during annual on my Tri-pacer this year. To do so I had to remove fabric just forward of the right side flap along with the aluminum sheet metal between the tank cover and the trailing edge. I noted that the inside of the wing in the area under the wing root fairing that there were large 3” x 5” inspection holes cut to allow access or to view control cables, gas tank fuel level sender, and fuel lines. These inspection windows left the fabric in the immediate area on the bottom surface of the wing loose. When it was time to close up the wing I laid extra patch material on the inside of the wing root to cover those holes and it has tightened up the whole underside of the wing fabric in that area. I had previously placed a large 12 x 16” patch over the two inspection port holes on the underside with new plastic rings. I have done no other modifications such as foam or Steve’s aluminum reinforcement in this area. I won’t know until I fly if there’s an improvement but just my hand thumping-drumming test suggests that it is much more taught in that area now. Still in work but should be in the air in a couple of weeks and will update on my success or not with this patch to reduce drumming.

[Raybanman]

How did it work? I have some serious drumming and am going through inspection covers like disposable contact lenses. We have the 180hp STC and it is a recurring issue. 20210513_152140.jpeg

Pat and Lisa
C-FMLJ
PA-22/20-180
https://instagram.com/dragonflystol?...=1qek1oa6jiejm

[Gilbert Pierce]

I use recessed covers with the spring attachments facing fore and aft. I then put a #4 PK screw thru the leading edge of the cover and thru the spring attachment. No more loss.
Recessed non-slip inspection covers - Recessed center and flanged-edge design will not creep off center due to vibration in propwash areas. Will not twist or vibrate.

https://www.aircraftspruce.com/catal...slipcovers.php

[Subsonic]

How did it work? I have some serious drumming and am going through inspection covers like disposable contact lenses. We have the 180hp STC and it is a recurring issue. 20210513_152140.jpeg

Pat and Lisa
C-FMLJ
PA-22/20-180
https://instagram.com/dragonflystol?...=1qek1oa6jiejm

It has worked very well on right wing. Left wing did not have the inside wing root area cutout as much and I've not tried to reduce the hole size for the aileron cables. I use the recessed inspection port covers just like Gilbert describes and haven't lost any covers since doing the work.

[McDaver63]

I wedged some rubbery type foam cut a little thicker then the gap between the aft spark and the fabric fwd of the inspection plates. That really seems to reduce the drumming quite a bit. I also did what Gilbert did by drilling and installing PK screws into the plates and thru to the retainer spring. Probably 80 hours now without loosing any inspection plates. I just have the dished type insp plates.