Saturday, April 26, 2014

Last Primer Shot

The rest of the week and even the Saturday morning where spent fixing the gazillion pin holes Van's had blessed these cowling parts with. I used the lightweight Superfil product for this job and am amazed about how good it is at this job. With the help of a squeegee (old credit card) the holes fill right up and there is not much to sand down afterwards and the Superfil sands real easy. The only downturn is that it takes 6-8 hours of at least 70 degrees to cure enough to get sanded.

After the Superfil had cured I sanded the whole surface of the parts with 320 grit dry and wiped it down with a micro fleece rag to remove the sand dust.
Then it was time for the last coat of primer to cover the light blue colored Superfil spots. I use the S-W Multi-Purpose Latex primer with ~10% Floetrol and a dash of water which looks like another 10%. After stirring it well it still has a consistency that looks thicker than what I would paint want to look like in an HVLP gun. So I use very little paint flow in the gun and 35psi and move very slowly over the surface to get good, fine coverage.

Now it should dry over night and then we will see in the morning if we need another sanding run before shooting the paint.

Wednesday, April 23, 2014

Priming Completed

Due to choosing the wrong filler for the numerous pin holes on the fiberglass parts I am not yet done with painting. In fact, I might not even be done with priming yet but at least I am getting there.
So what was wrong with the filler? I chose Stewart EkoFill grey (which also has UV protective properties) after my good results with their paint system. The EkoFill did turn out to be a nightmare to work with. The previous, somewhat older, can had gone bad and I received a fresh one right on Friday before the big paint weekend.
The EkoFill went on ok. The stuff is very watery and I did not feel good about spraying this as I expected it to just run off. So I used a foam brush as recommended for fabric. Well, the foam brush caused foaming of the EkoFill and it was impossible to completely remove the foam from the surfaces. Once dried I intended to sand the surface smooth but it turned out that sanding EkoFill is near to impossible to do.

It looked good when the first coats had been applied though:

The stuff has a rubbery consistency and dulls open coat sandpaper in a matter of 1-2 minutes. After 3-4 minutes the dull sandpaper does not cut anymore and just peels off little pieces of rubber similar to using an eraser. It took me 4 hours of tedious manual sanding wasting 3 sheets of 320 grit sandpaper and ending up with a not so pristine surface as I had wished for.
The episode was not over yet though. The EkoFill also did not fill the pinholes as I could not build up enough material to bridge them. This is due to being so watery and unsandable which made me not wanting to go through this more than once.

This is how it looked after the sanding episode:

The coat was super thin and it needed more to really get a UV protection. However, Latex paint also has a good UV protection and so I decided to leave it as is and to apply the S-W primer. I watered the primer down to a consistency that I was used to for the paint gun. That was about 20-25% water added to the primer. The primer did not mind but when I applied a stroke with the foam brush I saw that the EkoFill coat repelled the diluted primer so there was no way I could spray this. I had to apply a first coat of undiluted primer with the brush to get it to stick.

I built up the 7'x7' greenhouse that I had found on eBay to get a clean environment for the upcoming spraying.

I put the pieces inside and started applying the first primer coat with the foam brush.

I applied a few more coats with the brush to make sure the EkoFill was well covered before I got to spray the primer tonight for two coats on all 3 pieces.

I will let this sit to dry over night and then check tomorrow if it needs more. I hope it will be sufficient and I can sand this to prepare it for the paint coats.
BTW, I used Floetrol 10% and another 10-15% of water to dilute the primer which worked fine the HF HVLP gun.

Friday, April 18, 2014

Ready to Paint

Finally I got all my parts and supplies together to get into a weekend of painting!

It took quite a few trips to (different) Sherwin-Williams paint stores before I found competent help that guided me to the right paint. It was even more challenging though to get the color mixed that I wanted. Here are the results:

The color is Laughing Orange (SW 6895) that turns out to be a very nice Mango color when applied on a bright white background.
Resilience is supposed to be better than their All-Surface Enamel which I had intended to get as it does not yellow and chip because exposure to sunlight (Tucson is really tough in the sun department).
I intend to use EkoFill as a filler and UV coating on the fiberglass, followed by the Multi-Purpose Latex primer and then by the top coats.
The idea is to roll-on the filler and primer coats and then spray the top coat. We'll see how that all works out....

Wish me luck!

Monday, April 14, 2014

Painting with Latex

I had seen an EAA Webinar by Malcolm Morrison from EAA chapter 1327 who experimented with Latex on different aircraft for quite some time and with stunning results (at least to me).
You can find the webinar here and the summary webpage with photos and description here.

The fact that the paint is water-borne, cheap and readily available and available in any possible color, made the decision easy to give this a try.

I was about to prep the fiberglass surfaces of the cowl and spinner with EkoFill from Stewart Systems (after a thorough wet sanding with 220 grit) but the EkoFill I had bought about 1.5 years ago (and never opened) had gone bad. The can showed a very watery substance on the top and clumps of tar-thick filler on the bottom. No amount of stirring helped to dissolve the filler back into solution so I threw it out and ordered a new supply.

That means that I could not make any significant progress over the weekend and it also means that I probably won't be able to make any until the next weekend.

And here the pieces sat on the workbenches all ready to get primed.

I used the timeout to order some more tools for buffing and polishing the Latex paint and a protable greenhouse as a cheap makeshift paint booth as I do not want to build another wood-frame paintbooth for this simple job.

Friday, April 11, 2014

Where have you been?

I honestly had not meant to abandon this blog after the first Cross Country flight, if that is what you are thinking! It just seems that between peeling off more of the Blue Plague and doing a few more local flights, and preparing for the first scheduled maintenance there was not enough time to keep this blog up to date.

Well, now is the time to catch up on what has happened.

In between flights I tried to remove of the sticky vinyl that had turned out to be the Blue Plague. Now all that's left are partial two segments of the outmost lower left wing sheet.

A few weeks back I hopped in the plane with one of my Sport Pilot instructors and flew in and out of Tucson International which is a Class C airspace, and it's one of the busier ones. This was to get my endorsement for Class C Airspace as these explicit sign-offs are one of the unfortunate disadvantages of having a Sport Pilot ticket instead of a Private Pilot license. Class D and Class C are down and I might go for Bravo in a while to legally be able to fly through the VFR transition area over Phoenix International airport.

The plane reached 25 hours of engine time on the Hobbs meter last weekend and this means it is down for an oil change now. I wanted to use this mandatory cowl removal opportunity to extensively check for any kind of chafing on hoses and wires and also do a few fixes. One of them is to up the resistance value for the RPM wire a bit as it is still fluctuating on initial climb-out.
Another one is to finally prime and maybe paint the fiberglass cowl. This necessarily also included mulling over a possible paint scheme or if I want to add that dead weight of paint at all.
I came to the conclusion that my favorite scheme would be something close to this:

However, at this point I am still in strong opposition to anything that adds weight without any direct benefit.
The decision I made was to paint the fiberglass to protect it for now and to use a color that I would also fit this paint scheme in case I would end up having the plane painted some time down the road.

Priming and painting the cowl will take a little while and I took this opportunity to fix the problem of one of the exhaust springs rubbing on the inside of the cowl. It's the forward left spring.

I have already cut out the fiberglass and glassed in a sphere that curves away from the spring to give it some room. Here is the same area with the hole cut out and the edges roughed up for glassing.

and here after the glass was laid up.

After it had cured, I smeared some light-weight epoxy filler around the edge of the sphere in the tunnel...

... and put 3 coats of ceramic heat shield on the inside.

It's drying over night right now.

The oil change itself was a funny mess. I had ordered some of these copper crush washer that go underneath the drain screw head of the oil canister but when it was time do the oil change I could find them anywhere.
I put the old one on in the hope that I might get lucky as some sometimes they can be reused once. I was not lucky and have a very slow drip leak on the washer which will get replaced before I put the cowl back on.
I was also not able to change the filter yet as Rotax decided in its infinite wisdom to change the shape of the back of the oil filter a few years after I had built up my stock on Rotax and Rotax-compatible oil filters and TOOLS. Sure enough the filter wrench I had did not fit the filter to remove it. I have ordered new tools to do that when I get back to the hangar.

On a good note, though, I did not find anything wrong under the hood. No signs of chafing of hoses or wires or any leaks of anything - other than the contact point of the exhaust spring on the lower cowl.

And also the heat indicators on the electronic ignition modules do not show any sign of overheating (yet).

So now the plan is to finish up the fix on the lower cowl and then apply the Stewart EkoFill that I had bought a while ago to prep the cowl and spinner for painting. And I believe I might try to paint it with Latex paint from Sherwin-Williams. Maybe I try it on the spinner first ...