SGS 2-33 Canopy movement limiting cable failed... ensueing damage

This is probably common knowledge for some, but it caught my club by surprise. It is easy prevent this damage by replacing the canopy cable before it fails.

The cable that limits the canopy movement when the canopy is open failed. The canopy flopped over and slammed into the horizontal tube that runs front to back in the fuselage, bending it in several inches. The tube pivoted on the vertical member between the front and back seat, thus bending the same tube outward. Standing at the nose and sighting down the side of the fuselage, the tube is now S-shaped.

The responsible powers are consulting the knowledgeable experts, but I'd like to hear the range of expert and inexpert opinions offered on RAS. Surely this has happened to someone else before. How was the repair made?

I have no expert knowledge of aircraft structure, but the weld of the horizontal to vertical tube got a weird twist. The crude and direct approach of "bending back the tube" will stress the welds again and double any damage. The S-shape tube has lost much of it's strength in compression. Redundant parts of the tube structure are now picking up more load.

On Sunday, April 28, 2013 3:23:36 PM UTC+2, son_of_flubber wrote:

The responsible powers are consulting the knowledgeable experts, but I'd like to hear the range of expert and inexpert opinions offered on RAS. Surely this has happened to someone else before. How was the repair made?

Best way to fix a broken 2-33 is to buy a nice new glass trainer to replace it ;^)

Yeah, I know, cheap shot. Trouble is, the cost of fixing it may be more than it's worth. Or maybe you find a fuselage with busted wings...

Seriously, good luck, hope you get it flying again!

Kirk
66

When I worked at a gliderport in the 1970s, we treated most of the
2-33 forward fuselage structure above the level of the floor as non-
essential. All the real structural meat is in the triangulated truss
that supports the seats from below. Above that, the tubes smaller than
about 3/4" in diameter are mostly there just to support the fabric and
nose fairing. So I'm guessing that the damage you describe is pretty
much inconsequential, and that if you can find an A&P familiar with
the 2-33 structure the repairs will be pretty simple.

Thanks, Bob K.

On Sunday, April 28, 2013 9:23:36 AM UTC-4, son_of_flubber wrote:
This is probably common knowledge for some, but it caught my club by surprise. It is easy prevent this damage by replacing the canopy cable before it fails. The cable that limits the canopy movement when the canopy is open failed. The canopy flopped over and slammed into the horizontal tube that runs front to back in the fuselage, bending it in several inches. The tube pivoted on the vertical member between the front and back seat, thus bending the same tube outward. Standing at the nose and sighting down the side of the fuselage, the tube is now S-shaped. The responsible powers are consulting the knowledgeable experts, but I'd like to hear the range of expert and inexpert opinions offered on RAS. Surely this has happened to someone else before. How was the repair made? I have no expert knowledge of aircraft structure, but the weld of the horizontal to vertical tube got a weird twist. The crude and direct approach of "bending back the tube" will stress the welds again and double any damage. The S-shape tube has lost much of it's strength in compression. Redundant parts of the tube structure are now picking up more load.

Remove fabric.
Straighten bent stuff which is probably the stringer and the small channel pieces that support it. Straighten and reinforce anything broken(likely the small channel pieces) which may require a bit of welding.
Replace fabric.
Any decent A&P should be able to do this.
All done iaw AC43-13 as provided for in maintenance manual.
NOT a big deal.
This should be about 10-12 hrs including fabric work.
Good Luck
UH