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| OH NO.! |
At this point the builder stood back to admire his work and OMG the trailing edge of the tab was clearly not in line with the elevator skin. A loud crash of a builder hitting the wall was to be heard. After contacting the factory a series of photos's were received for guidance.
I had swapped the inboard and the adjacent rib with the other frame's due to a mix up in the skin labeling as both had been cut and it was felt that this would allow me to proceed with both elevators. In trying to fix the problem by swapping the affected ribs it may have had unintended consequences during the process of assembly .
Note: The frames are symmetrical so there is NO port or starboard until the tab is cut and positioned, its the relationship between the skin and frame that counts at assembly.
What to do
Note: The frames are symmetrical so there is NO port or starboard until the tab is cut and positioned, its the relationship between the skin and frame that counts at assembly.
What to do
When you create a problem like this, how do you fix it is the $64 question.
After a examination of the frame it was decided to remove the #2 rib, behold most of the misalignment was released. The next decision was to re-manufacture the trim tab spar as it was only fixed with clecos and it would allow me to start with a clean slate.
A fixed reference was created using a 1.5 meter length of 25 x 25 x 1.5 aluminium angle clamped to the elevator for all of the assembly tasks. One of the big differences between the factory and my procedure is the availability of jigs. The frame is a moving feast for most of the assembly period and this may have amplified any errors made.
A aluminium packer was installed at the underside of the outboard rib [#1] to improved fit to the new spar [see photo insert above]. The new spars were folded from 0.030'' aluminium [what was available] with the overall width matching the first full rib #3 and a second spar was folded with the overall width reduce 3 mm to clear the inside face of the first.
The procedure followed the previous blog on the original installation except that I started with the top spar to make alignment a little easier.
The front spar was cleoed at two places to allow a re-position if required. Next the lower spar was fitted to the underside of the first spar and cleoced at two places.
The spars were refitted and adjusted until the angle between the spar faces and the skins were are in alignment. The final tasks was to fix the two using 5/32 rivets pitched at 30 mm using the jig supplied to mark the spar.
The second rib had its mounting removed and was installed as a floating rib attached to the skin only.
As this had created most of the previous error it was felt that it should not exert force during re-assembly.
The original tab assembly was refitted and aligned using the angle as a guide and once satisfied the a cleco was installed at the inside rib. As the hinge was already drilled, alignment of the next hole required the used of a tab clecoed to the rear spar that allowed the hinge to be opened up, positioned and a hole match drilled. The tab was refitted and the whole alignment checked again - once satisfied two 5/32 rivets were installed.
The whole assembly was carefully checked and once satisfied the top spar's were match drilled from the skin's and clecoed to ensure that no unwanted movement occurred and then the trim tab hinge was matched drilled and pop riveted.
Once fully satisfied the top skin was pop riveted to the tab spar and the ribs except at the last rib and main spar to allow the D nose to be fitted later. The reason was two fold, one to make the final work to install the tab motor easier and secondly to CLAMP the frame up with the rivets
This time I was glad to see the finished product.
After a examination of the frame it was decided to remove the #2 rib, behold most of the misalignment was released. The next decision was to re-manufacture the trim tab spar as it was only fixed with clecos and it would allow me to start with a clean slate.
A fixed reference was created using a 1.5 meter length of 25 x 25 x 1.5 aluminium angle clamped to the elevator for all of the assembly tasks. One of the big differences between the factory and my procedure is the availability of jigs. The frame is a moving feast for most of the assembly period and this may have amplified any errors made.
A aluminium packer was installed at the underside of the outboard rib [#1] to improved fit to the new spar [see photo insert above]. The new spars were folded from 0.030'' aluminium [what was available] with the overall width matching the first full rib #3 and a second spar was folded with the overall width reduce 3 mm to clear the inside face of the first.
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| First spar begin inserted - final assembly see insert |
The procedure followed the previous blog on the original installation except that I started with the top spar to make alignment a little easier.
The front spar was cleoed at two places to allow a re-position if required. Next the lower spar was fitted to the underside of the first spar and cleoced at two places.
The spars were refitted and adjusted until the angle between the spar faces and the skins were are in alignment. The final tasks was to fix the two using 5/32 rivets pitched at 30 mm using the jig supplied to mark the spar.
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| Second Spar added with the first fixing |
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| Riveting Tab Spar |
The second rib had its mounting removed and was installed as a floating rib attached to the skin only.
As this had created most of the previous error it was felt that it should not exert force during re-assembly.
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| Tab Assembly |
The original tab assembly was refitted and aligned using the angle as a guide and once satisfied the a cleco was installed at the inside rib. As the hinge was already drilled, alignment of the next hole required the used of a tab clecoed to the rear spar that allowed the hinge to be opened up, positioned and a hole match drilled. The tab was refitted and the whole alignment checked again - once satisfied two 5/32 rivets were installed.
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| Checking alignment of tab |
The whole assembly was carefully checked and once satisfied the top spar's were match drilled from the skin's and clecoed to ensure that no unwanted movement occurred and then the trim tab hinge was matched drilled and pop riveted.
Once fully satisfied the top skin was pop riveted to the tab spar and the ribs except at the last rib and main spar to allow the D nose to be fitted later. The reason was two fold, one to make the final work to install the tab motor easier and secondly to CLAMP the frame up with the rivets
This time I was glad to see the finished product.
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