Twisted: Canopy repair

In December the Twister had it's annual inspection and after sending off the paperwork I did not get anything back through the post - the LAA normally turnaround a Permit the same day if all is in order.

So after a week I phoned the office and was told - "Oh yeah that's on hold as there is a Repair that has not been approved yet".

This Repair was the one done to the canopy frame and hinges after I got back from the Oshkosh epic in 2017. The Repair paperwork was done to satisfaction (or so I thought) in February of 2018 - so what was the hold up?

Their excuse was that they never received the email I sent which contained all the photos and answers to their questions. Quite frankly I do not believe this story as if the email did not arrive then it would have bounced back to me - which it didn't. It is clear that the LAA don't have any kind of system in place to ensure something is not processed internally. I had assumed all was well as I had not heard back about the Repair.

Anyway on sending the email again it was swiftly approved - except now I had to get an inspector to look at the repair and sign off what I had done - more paperwork!

So I arranged an inspection and he discovered that the reinforcing carbon I had used to thicken up the hinge brackets was cracked at bottom end - not surprising since I had done this repair 'in the field' and so the reinforcing had a weak point which was at the end where it was not really bonded to the existing hinge as it was just butted up to it.

Actually I was happy in a way to have another opportunity to repair the hinges properly this time, so I decided to take the canopy off and repair it at home.

I started off by taking away some of the reinforcing carbon, totally so in the region where it had cracked.

I then made up two small blocks of wood that would sit inside the hinges and allow a clamp to force the carbon up into the corner where it had cracked before - thereby ensuring a complete bond this time round.

The back hinge was not cracked but I decided to do this repair to both hinges anyway to make them right.

The front hinge got a further layup of 3 layers of carbon in a strip which was laid over the entire surface - see pics - to closeout the layup and add even more strength to the hinge. The front hinge is subject to much more flex than the rear one due to it's distance from the retaining wire which supports the rear hinge much better as it is closer to it.

After the carbon work was done I primed and painted the whole area, making a much better job than I did before.

The canopy is now back on and signed off by my inspector - I am now waiting for the Permit to arrive but this has taken more than a week already. In the meantime I have used the time to touch up a few things here and there but hope to get the Permit soon.

If I could start from scratch and build again I would consider reinforcing the inside of the hollow canopy frame with runny flock in the area around the hinges. I would also take away some of the micro in this area and replace it with carbon and also reinforce the hinges as I've done here too.

Canopy off and at home to do the repair - a much better idea than trying to do it 'in the field'.

This shows the crack that developed in the end of the carbon reinforcement - it was just butted up to the end and therefore not really bonded to the round portion of the hinge.

Two blocks of wood, shaped to fit and wrapped in Duct tape to release, enable clamps to force the new carbon reinforcement into the corners of the hinge.