Wednesday, October 31, 2012

All Cowl Drilling Completed

I took on the drilling of the side hinges today. The first hole is the toughest as you have to support the hinge from behind and with the engine in there, it's kind of hard to get there.

Then the vertical side hinges were up for drilling. I also was about to run out of #40 clecos so I resorted to reduce the amount already in use by half.

After the halves had been connected they were sitting quite tight on each other. Too tight in fact, to allow paint to get sprayed on at some point. All had to get removed to give room for sanding and then everything was put back together to check if it was enough. Fortunately it was.

Everything came off again for some countersinking and riveting to be done eventually.
Before that I decided to trim the cutout for the nose gear a bit wider.

The rest can be done at night and mostly in the shop. The countersinking I rather do outside to not collect hazardous dust in the shop but the riveting can definitely be done inside.
Looks like I am finally getting over this dreaded task!

Tuesday, October 30, 2012

Top Cowl Drilled

After match-drilling the top cowl in two locations and marking the areas where the cowl would have to be trimmed to allow for a recess where the hinge pins will be secured, I could take the cowl off and sand the lower half a bit more to allow proper clearance on the aft left side.

The sides look like there would be a very large gap but that closes easily when pushing inside a bit. It should look great once the side hinges are drilled and clecoed.
But before that the top had to get drilled to the aft hinges.

Now that it is in its final position, it appears that the left aft side of the lower cowl has to get trimmed just a tad more to have a perfect fit.
I should probably remove the freshly drilled clecos on the top anyway to clean out any debris caught between the fiberglass and the hinges.

Sunday, October 28, 2012

Mating the Halves

This is another 2-day post, covering the weekend.

On the first day I continued trimming the built up gap filler. The flox is making the resin really tough and tough it was to sand it down. To have an idea how much had to be removed, I put the top cowl on and marked the filler with a black Sharpie along the edge of the top cowl.

This gave me a pretty good idea what had to get removed. I also trimmed the inside and outside of the trimmed area a bit to smoothen it out.

At about the center of the filled area, I found a recess that needed to get built up before I could completely trim it down to the marked line. So, I had to let this cure again over night and that ended the short work day 1.

The next day and with a fresh supply of 3X sand paper I was able to quickly remove the excess resin and to confirm that the top cowl had a good fit now.

Then the outside had to get trimmed back. To avoid scratching the original surface on the lower cowl, I applied electric tape underneath the filled area.

Using wet 220 grit sandpaper I was able to accomplish a pretty nice surface for a first sanding. I removed the mylar tape and will leave the surface for now until the fiberglass gets prepped for priming.

The next step was to trim the lower edge of the step that still had some minor interference with the aluminum - on both sides.

And that got me back around to the instructions again. Now it was time install the side hinges on the lower cowl.

Then the hinge pins were installed, trimmed and bent.

Finally I put the top cowl back on. Unfortunately, there seems to be the need for a minor trimming at the rear left side. It appears that that filled area had not been trimmer down quite enough. It just needs a little touch ...

Sunday, October 21, 2012

Filling the Gap

I worked in the cowl again this weekend. It seems I'm done with trimming now and I could work on connecting the two halves on their sides with another set of piano hinges - if it wasn't for the gap I had created on the left side.
My first attempt to fix this was by clamping a back plate in place (another strip of fiberglass) and filling the recess with resin with a lot of flox mixed in.

The back plate had its slick side facing the resin and I also applied some wax on it so I could easily separate the cured resin from the backplate. The lower area of the cowl beneath the gap was covered with a strip of packing tape.
The setup cured ok over night and I was also able to separate it without any damages. Unfortunately, I had a sag that needed filling from the inside of the cowl area, so I sanded the resin and applied some more floxed resin.

Once this is all set, I hope it has enough strength to hold onto the small area of contact with the rest of the cowl while I trim it back to the correct shape. When the piano hinge is installed, it will help to stabilize the gap filler but before that happens it will be rather fragile.

Monday, October 15, 2012

Top Cowl Aft Edge Fitted

After another 1.5 hours of sanding and taking off and putting on the top cowl half, it finally cleared the edge of the sheet metal at its aft end.

The horizontal gap on the right side looks promising, too.

What I did not like so much was the left side. It turned out that it did not come down enough after it cleared the aft edge to fully compensate for the widening gap.

I think I will have to do some filling work on this side to make this look prettier. And I am not quite sure yet how to best approach this...

Anyway, the next step will be to batch the horizontal sections of the lower and the top cowl so I can finally install the piano hinges that will connect the two halves.

Monday, October 8, 2012

Top Cowl Almost Fits

I am back from Hawai'i for a week now, but I couldn't get myself to start sanding on the top cowl until tonight.
I had it already taped off so all I had to do was really start sanding.
This is the result after 45 minutes of grinding away on it:

On the right side I just have the perfect clearance to the skin in one spot. Now the rest has to follow that example and I would be happy.
When you look at the side it appears that there might be a gap. You have to know that the aft end is still resting on the skin and it will lower a bit when it fits right. I think it should just come down enough to close the gap.