Posted Wednesday, May 13, 2020 @ 04:54 AM  

This is an amateur giving you info on how he attempted to solve a problem, and not necessarily how you should solve it. I got advice from Britain's 'Mr Fournier', Dave Bland, but he should not be blamed for any mistakes I've made.

One of the Camlok fasteners kept falling out of my lower cowling, so a repair was in order.

This is how I did it. First I drew two long right-angled lines in Sharpie permanent marker on the outside to indicate the centre of the replacement hole when the repair was finished. Then I taped over the hole with shiny self-adhesive aluminium tape, in the centre of which I put a small disc of that tape so the resin wouldn't stick to it.

Then, broadly using this Diamond repair scheme,

I chamfered (scarfed) out a wider circular area with my Dremel (actually a cheaper Ozito).

Cutting out discs of woven glassfibre was harder then it looks, but I guess they don't have to be absolutely circular.

I used West System epoxy, mixed (very approximately by eye) at five-to-one. It seemed odd to,put the big disc in first with the smaller ones successively on top of it, but Dave assured me that was the correct way to do it.

Then, because it is a tad chilly here in Perth's autumn, I carefully speeded the chemical reaction a little with the heat gun.

The inside result doesn't look too bad to my untutored eye, although it's obviously a bit bubbly, too thick and will have to be sanded down.

Tomorrow I'll check the outside, fill where necessary, drill the hole and pop back the Camlok.

[Edit by Bob Grimstead on Wednesday, May 13, 2020 @ 05:02 AM]

[Edit by Bob Grimstead on Friday, July 31, 2020 @ 11:16 PM]

Posted Friday, July 31, 2020 @ 11:29 PM  

This is how the repairs looked from the outside with the shiny tape removed

There was also a split at the front of the cowling and a couple of areas where the engine had fretted against it, so I resolved to patch those areas as well.

The previous repair (ten years ago, by a friend) clearly wasn't strong enough.

I carefully cleaned the areas I was going to work on with avgas to dissolve the oily patina. I deliberately left the other parts of the cowling oily so that afterwards I could easily peel off any unwanted dribbles or runs.

Here are the front and abrasion repairs with the excess dribbles peeled off the oily parts.

Once the resin had set hard (three days), I extended those crosses back to their centres, made a pilot hole with an eighth-inch bit and then drilled out the Camlok holder holes with my Irwin Multi-bit.