Something I thought might be of interest to RV-10 people. Perhaps other models as well. I also shared this with Van's.
I was laying on my back doing some modification to wiring underneath the instrument panel. While I was doing that work the control stick was deflected to the left. After completion of my work underneath the panel I discovered that the control stick was jammed in the full left position. Forward / rear travel was unrestricted, but there was no ability to move the stick left / right.
At the ailerons themselves, the right aileron (deflected down) could be deflected only very slightly (consistent with normal control system "slop"), however, the left aileron was locked very tightly in the full up position. No movement at all was possible.
I disconnected the left aileron push rod (W-1018) at the bellcrank inside the wing. (See page 23-9 in RV-10 plans). Only after lifting up on the rod did I free the aileron.
Here's what I discovered.
1. During final aileron installation/rigging what I believed to be aileron contact at the aileron stop was actually the shopped end of the vertical rivet on the W-1018 pushrod contacting the rear face of the rear wing spar opening. Please see the attached image. This contact mimicked what could reasonably be determined to be aileron stop contact.
The ailerons demonstrated required deflection angles even with the rivet/rear spar contact.
With the rivet acting as the false aileron stop there was approximately a .125 gap still remaining between the aileron and the actual aileron stop.
The behavior of the rivet/spar contact was easily confused with solid aileron stop contact. Furthermore, it is not easy to visually confirm proper aileron stop contact.
Both ailerons had this condition.
2. Over time the shopped end of the rivet, while making contact with the rear face of the rear wing spar, lost some of its squared finish. The rivet had rounded just enough to allow the rivet to "hop" over the rear spar and then snap down snugly on the forward side of the spar.
Remember that, due to the aileron pivot geometry, the W-1018 pushrod moves forward and down with forward movement. So when the pushrod moved forward, and the rivet "hopped" over the rear spar, the pushrod was held down even more securely with the rivet jammed on the forward side.
3. I had to add clearance at the bottom of the rear wing spar openings on both wings in order to assure no rivet/spar contact. The ailerons now properly contact the aileron stops without rivet interference.
4. This situation would likely have been unrecoverable if it had happened in flight. However, to get this situation to occur in flight would have been the result of hard-over full control stick deflection- something I hate to think of as responsive as the RV-10 is.
See the pics.
David
I was laying on my back doing some modification to wiring underneath the instrument panel. While I was doing that work the control stick was deflected to the left. After completion of my work underneath the panel I discovered that the control stick was jammed in the full left position. Forward / rear travel was unrestricted, but there was no ability to move the stick left / right.
At the ailerons themselves, the right aileron (deflected down) could be deflected only very slightly (consistent with normal control system "slop"), however, the left aileron was locked very tightly in the full up position. No movement at all was possible.
I disconnected the left aileron push rod (W-1018) at the bellcrank inside the wing. (See page 23-9 in RV-10 plans). Only after lifting up on the rod did I free the aileron.
Here's what I discovered.
1. During final aileron installation/rigging what I believed to be aileron contact at the aileron stop was actually the shopped end of the vertical rivet on the W-1018 pushrod contacting the rear face of the rear wing spar opening. Please see the attached image. This contact mimicked what could reasonably be determined to be aileron stop contact.
The ailerons demonstrated required deflection angles even with the rivet/rear spar contact.
With the rivet acting as the false aileron stop there was approximately a .125 gap still remaining between the aileron and the actual aileron stop.
The behavior of the rivet/spar contact was easily confused with solid aileron stop contact. Furthermore, it is not easy to visually confirm proper aileron stop contact.
Both ailerons had this condition.
2. Over time the shopped end of the rivet, while making contact with the rear face of the rear wing spar, lost some of its squared finish. The rivet had rounded just enough to allow the rivet to "hop" over the rear spar and then snap down snugly on the forward side of the spar.
Remember that, due to the aileron pivot geometry, the W-1018 pushrod moves forward and down with forward movement. So when the pushrod moved forward, and the rivet "hopped" over the rear spar, the pushrod was held down even more securely with the rivet jammed on the forward side.
3. I had to add clearance at the bottom of the rear wing spar openings on both wings in order to assure no rivet/spar contact. The ailerons now properly contact the aileron stops without rivet interference.
4. This situation would likely have been unrecoverable if it had happened in flight. However, to get this situation to occur in flight would have been the result of hard-over full control stick deflection- something I hate to think of as responsive as the RV-10 is.
See the pics.
David
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