Saturday, May 3, 2014

RPM Is Stable Now

The 47kOhms resistor did the trick. No more fluctuations, not even during initial climb out. This has been verified today during 3 hours of flying from AVQ to PAN, from PAN to FFZ and back to AVQ. Payson was beautiful and the restaurant has nice food for around what I pay for a gallon of AvGas at Falcon Field.

Now let's plan for a few days in Sedona!

Friday, May 2, 2014

Cowl Painting Done ... For Now

I completed the paint job this week. As a matter of fact I am having my car sit outside with the painted pieces inside waiting to go to the hangar to install them as I am typing this.
Why am I saying "for now" in the title then?

That is because a few things went wrong and now I know how to do it better - much better, actually - but I do not want to ground the plane for another 2 or 3 weeks to fix it right now.

The oil change is complete, I swapped the RPM line resistor and she's grounded for too long already.

So what went wrong with the paint job?

I used Floetrol at around 10-12% and some additional water of around 10-15% but the paint was still a bit thick for spraying. I went with it because I was more afraid of seeing the paint run off the many vertical areas and creating runs that would have needed sanding.
The way the paint dried with that thick coating was somewhat bubbly which created an orange peel effect even though I threw the last coat on thick and wet. The only way to remove the peel is to sand it down to an evenly dull finish and then build the paint back up with a watery consistency and thin wet coats.
I tried this on the spinner as that is the only small piece that has vertical surfaces and so it was easy for a quick test (and it would have been easy to fix had I created runs). I sanded it lightly with 400 grit wet, not enough to completely remove the peel but enough to reduce it drastically.
Then I used isopropylic alcohol (70% ) and some water to dilute the paint enough to really get down to a watery consistency. I was very aggressive with diluting it this time as I wanted to see if this worked or not.
I sprayed it on and I was able to create a very smooth and even coat in no time. The coat dried very quickly and the result is encouraging. The finish is a lot smoother than before, only disturbed by the peel effect that had not been completely removed.

So what would have to happen to get the even glossy finish that I wanted for the rest of the cowl is to sand it down to a smooth surface and then use heavily diluted paint to build it back up in 2 to 3 thin coats. I will likely do this but not right now. I left the paint surfaces as is and won't apply any wax or anything that could later be a problem when sanding down and repainting. For now I will fly this as is and at the next oil change, I will take a stab at this again. It will likely be winter at that time and the lower temperatures could help extending the drying time and create an even smoother surface than what I saw with the test on the spinner.

I got to the hangar and installed the cowl again. What was proven immediately is that the paint is too soft. I hope it will dry eventually and get a harder surface as it is very tender at this time.

Tomorrow morning we'll go flying!