So, since Mark posted the thread on the elevator spar crack on his 7a, the MidSouthRV group has been re-inspecting our magic carpets and we found some of the loose jam nuts others noted but we also found this. The implications seemed worthy of consideration since flutter seems to be a concern these days.
When pulling and pushing on the elevators, we checked the trim tab for movement, not much initially but it felt funny. When we applied a little more pressure, it jumped about two inches which was pretty shocking. We found that the bracket holding the manual trim cable had come apart but the nut seems to jam in the trim plate and sort of holds it in place.....sort of.
As soon as you apply reasonable pressure, (more than a little but not a lot) it would move a couple of inches in both directions. When the nut breaks loose, there is nothing really holding the cable in place which lets the whole trim tab move as the cable moves inside the elevator.
This was on a RV8 with manual trim. Not sure this is SOP but it is the way it was. The only thing holding the manual cable in was the cable nut which had been spot welded to a small steel plate which rivets to the attachment plate. Why this isn't a piece of solid 90 degree stock or a formed attachment with a nut on both sides might be open to question.
Not trying to debate the design but the pictures show what happened and it probably is worth checking as a trim tab flopping in the wind probably isn't what we want. This is the nut (the only one) that was welded to the inspection/attachment plate.
This was the plate clearly showing the weld break and there was no weld buildup apparent on either surface.
Our buddy flies solo most of the time and uses virtually no trim. No idea how long it had been that way but we are sure it happened since the last condition inspection.
We think it's worth checking out if you have a manual trim system with this attachment method.
Edited 9/30/13 This is covered by SB 06-9-20 on the Vans site http://www.vansaircraft.com/pdf/sb06-9-20.pdf
When pulling and pushing on the elevators, we checked the trim tab for movement, not much initially but it felt funny. When we applied a little more pressure, it jumped about two inches which was pretty shocking. We found that the bracket holding the manual trim cable had come apart but the nut seems to jam in the trim plate and sort of holds it in place.....sort of.
As soon as you apply reasonable pressure, (more than a little but not a lot) it would move a couple of inches in both directions. When the nut breaks loose, there is nothing really holding the cable in place which lets the whole trim tab move as the cable moves inside the elevator.
This was on a RV8 with manual trim. Not sure this is SOP but it is the way it was. The only thing holding the manual cable in was the cable nut which had been spot welded to a small steel plate which rivets to the attachment plate. Why this isn't a piece of solid 90 degree stock or a formed attachment with a nut on both sides might be open to question.
Not trying to debate the design but the pictures show what happened and it probably is worth checking as a trim tab flopping in the wind probably isn't what we want. This is the nut (the only one) that was welded to the inspection/attachment plate.
This was the plate clearly showing the weld break and there was no weld buildup apparent on either surface.
Our buddy flies solo most of the time and uses virtually no trim. No idea how long it had been that way but we are sure it happened since the last condition inspection.
We think it's worth checking out if you have a manual trim system with this attachment method.
Edited 9/30/13 This is covered by SB 06-9-20 on the Vans site http://www.vansaircraft.com/pdf/sb06-9-20.pdf
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