Thursday, October 29, 2015

DIY Painting the RV-12 airplane

During a 9 month period I worked at painting the RV-12 airplane myself. It has proven both frustrating and rewarding. By May of 2015 most of the final painting was done except for the wings. My past painting experience was limited to a Cessna 150E I painted with enamel about 15 years ago using old school high pressure paint guns.

Please read and understand the Disclaimer on the right of this page, before continuing on and using any information found here! For the RV-12, I used Ranthane polyurethane paint. This is a single stage system, as opposed to a base coat clear, coat system. Being a polyurethane you must wear a fresh air breathing system verses a respirator.

Equipment Used

For applying paint and for a fresh air breathing supply, I purchased a Citation Stage 4 combination. The more stages the turbine has the higher the pressure and the more finely divided the paint spray. For this paint I don't think the 3 stage unit would have worked very well. My paint booth was a made from a Costco portable carport. The floor was covered with plastic floor protector from Home Depot. For filtration I used home HVAC filters on the intake and exhaust fans. For exhaust I used fans with totally enclosed motors. I DIDN'T USE BOX FANS! Box fans have open motor windings and can ignite paint fumes if the fume to air mixture is correct. As a kid I had the experience of seeing (feeling) a vapor fire from 100 ft away and will never forget the shock wave that hit me. Lighting should also be sealed.

The outline of the process I used is as follows:

Acid etched and alodined the aluminum.

Filled the rivet heads with Superfil epoxy a lightweight fill by Polyfiber. I found by thinning it slightly with acetone it flowed through the syringe and blunted needle much easier. These were purchased at a feed store and then the needle tip was cut off and filed.

Below is a picture of a good and bad fill job.

Next I sanded the extra epoxy flush with the head of the rivet being careful not the sand any of the metal away. To help protect the skins I made a sanding guide out of a piece of polypropylene plastic sheet.

The fiberglass parts need a different treatment. These were filled with UVSmooth Prime. Starting first with a razor blade to scrape the filler into the pinholes. This was then followed up with rolled and brushed coats.

Any remaining pinhole were filled with thinned Superfil epoxy, using a razor blade as a scraper to fill the imperfections. In hindsight using West System thinned with acetone as a first coat would have reduced a lot of work.

Next both aluminum and fiberglass surfaces were primed with Epibond Epoxy primer. The instruction say the coats should be translucent (you can see the aluminum though it), but I found by going a little heavier with the primer I didn't need as many coats of the Ranthane top coat, especially the Vastel white. Otherwise color variation could be seen though the top coat. Some of the rivet heads didn't look good,so these were refilled and spot primed.

Before starting a painting step the floor was mopped with soap and water and the aircraft parts were grounded to help reduce any static.

After this, The final top coats were applied.

The stripping decals came from AEROGRAPHICS. They are a great company to work with. The stripping should last 8 years outside and 10 to 12 year if the airplane is hangered. The photos below show the steps of installing them per Aerographic's instructions.

Getting the bubbles of air out around the rivets was a challenge. After they set for a few days most small air pockets disappear. The larger ones were poked with a straight pin and the air worked out. Also on some I had to apply heat with a heat gun to get them to lay down completely. It just takes time and careful work.

Problems; "The Good, the Bad and the Ugly."

When it good it good!

But it is a fine line between orange peel and runs. I found with the weather here in Oregon and the equipment I used, I need to mix the Ranthane as follows. One part base paint mixed with one part catalyzer. Let set 20 minutes and then thin with their urethane reducer (thinner) 50% to 100%. This is more reducer than the instructions call for, but came from Polyfiber's paint expert.

So to put the thinning another way one cup base, 1/2 cup catalyzer and let set 20 minutes. Then add approximately one to 1 1/2 cup reducer. Start with the lower amount of reducer and try vertical paint strips as mentioned in the paint instructions. Increase reducer as needed.

Or I ended up with this: orange peel.

Working with Ranthane is a little like the joke about equestrian medicine, if anything happens to the horse just shoot it. Imperfections in the top coat can't be color sanded and buffed out. Well technically it can, but it won't polish to a high gloss like the surrounding paint. I know I tried many times. So the only way to fix it is to sand it down the entire panel with out going through the primer and repaint it. Yes, the entire panel otherwise there will be funny tape lines in the panel unless you are changing color.

Drips can sometime be fixed while they are still wet. Basically you wait for the surrounding paint to get tacky and use a loop of new masking tape to lift off the drip. After the area has set for the required time between coat (usually 45 minutes) you carefully re-coat the area. Try it on a test piece before using it in on the actual paint job. It takes practice to get it right.

There are many different problems that can arise in painting and there are some good guides online to identify and solve the problem. Like the printshop supplier told me, painting is more about how to fix and prevent problems than just painting. Hindsights

Would I paint my own airplane again? Loaded question! It would have been nice to just give it to someone else and have it come back all done and probably would have been flying sooner. Good painters charge a lot and for good reason, prepping and painting an airplane is a lot of work.

I like knowing how to finish the airplane so if there is ever a need I could repaint part or all of it. At the same time, I know every flaw in the paint (even though other people don't appear see them) they bug me, but not as much as if I had the same problems in a professionally painted airplane. Would these flaws exist in a professional paint job? Yes, because I have seen them on the flight line at air shows.

Two things I would do differently, rent a professional paint booth. And use a slightly darker primary color. When painting with the Vastel White I would start to go "snow blind" in the paint both and couldn't see where I had stopped with the last coat. This would end up with too much paint and a run that had to be fixed. With the Agcat Grey I didn't have that problem. Also some colors hide flaws better than other colors.

So to answer the question if I'm crazy enough to build another airplane I'd paint it as well.

Would I fill the rivets again? Probably, I really like how it looks but didn't like all the work involved.

Would I use Ranthane again? I love the durability of the finish. Poly Fiber Aircraft Coatings is a great company to work with! If I were painting a fabric airplane I would use it without a doubt. If it was an aluminum airplane like the RV, I think I'd try a Base Coat Clear Coat system just to see the difference. It's the experimenter in me. I can say if Poly Fiber made such a system I would use it.

I've been told Base Coat, Clear Coat systems weight less because the chemistry is different. With a single stage paint the gloss has to migrate to the top of the paint and the color sinks to the bottom. I have no proof of this but it sounds plausible.

Below is a picture of the final product.

Friday, September 4, 2015

Vans Aircraft RV-12 Airplane Build: First Flight, Fly-off and Final Adjustments

The big day came for the RV-12 and the first flight. As I mentioned in an earlier post Mike Seager did the phase 1 fly-off on my RV-12. It started with another complete inspection by Mike and myself to make sure nothing was missed. Then after final prep Mike climbed aboard, warmed her up and did the first flight!

Over the next two days the prescribed test flights and Van's flight cards were completed, with inspections between each flight.

A couple of things did surface during the test period and are as follows:

Idle was set ~100 rpm too high and was reset to 1450rpm.

One of the landing gear bolts was found slightly low on the torque value when all the bolts were re-torqued.

I placed a small piece of very thin UMHW tape over part of the battery frame as I was told this can short out when putting a trickle charger on the battery.

One of the exhaust springs was wearing on the cowl. So I cut a clearance hole and re-fiberglassed and refinished a depression in the inner cowl duct.

The Take-Off trim indicator was setup.

The left wing was heavy so the right wing was crimped per Van's RV-12 directions.

A rudder trim tab kit was installed and adjustment.

After all of this and the log book sign-offs, Mike and I spent and hour or so flying and preforming take-off and landings.

The next project was to take it up to Pacific Coast Avionics and get a transponder check.

The RV-12 is a great fling airplane! If you are thinking of building one get a test flight from Van's. It's a free test flight that will only cost $70,000:) Enjoy- Vern Smith

Thursday, August 27, 2015

Vans Aircraft RV-12 Airplane Build: Transitional Flight Training

It's been about 5 years since I flown regularly. So the first order of business was to get current in a Cessna 150 and get a few hours of flying, all air work, including stalls, step turns, slow flight, takeoffs and landings. With this under my belt I scheduled parts of two days for transitional training with Mike Seager. If you look on the Van's Aircraft website you will find him listed under flight training. Vernonia, Oregon is a quant little town West of Portland, Oregon. There are some neat restaurants and we stayed in a nice little Bed and Breakfast called Rock Creek B&B.

So that brings me to the transitional training. Mike and I started with about an hour of ground training centered around flying an RV airplane. Then the flying started after taking off from Vernonia's airport (a small grass strip) we headed to the airport at Scappoose for pattern work. With 5100 feet of runway there is plenty of room to learn the intricacies of the RV-12. Then it was back to Vernonia a coupe of hours of rest (ay least for for me, Mike had a second student) and then back up for another 1.6 hours of flying in the afternoon. Day two was similar but without the ground instruction. This is longer than some may need, but I'm happy I spent the time.

What did I learn? I learned how to fly with an EFIS, which is just different from steam gauges. How to work the Auto Pilot. Some of the idiosyncrasies of operating the Rotax 912 engine. This includes how much the Rotax's RPM is affected by in flight loading and unloading of the prop. Flying with a castering nose wheel. That ham-footed rudder work that works fine with a Cessna doesn't "fly" with an RV. Slipping the RV-12 to loose altitude on final. And much, much more.

So next comes the intial test flight and phase 1 fly off. Stay tuned!

Monday, August 24, 2015

Vans Aircraft RV-12 Airplane Build: Newest RV-12 in the World (at least for a short time)

With the RV-12 completed, I've been working with Gary Brown a DAR in Independence Oregon to obtain a airworthiness inspection and certification. Today was the day for the inspection. After looking it the airplane, Builder's Log, Maintenance Logbooks and covering the Operating limitations and other paperwork I was awarded an Airworthiness Certificate!

Gary had a few suggestions that make sense. First Van's Aircraft is working on a split baggage compartment bulkhead. He said get it or build it, as it will allow inspection of the tailcone without removing the fuel tank. I'm planning to do this at the first conditional inspection.

In the picture below you can see the split floor panel that Van's offers that I installed previously.

Second tie-wrap the fuel pressure sensor to the radiator hose (as pictured below.) This will help reduce vibration on the sensor.

With the inspection out of the way next is to get myself ready for flying the RV-12. For this I have scheduled time with Mike Seager

Wednesday, August 12, 2015

Vans Aircraft RV-12 Airplane Build: Final Assembly (part 16) Elevator trim Indicator, Run Up and Finish Up

Reference: RV-12 Acceptance Procedures

Working on the RV-12 today I notice there was no indication for the Elevator trim. And no mention of calibrating it in the plans. Looking at the Dynon guide there was a brief statement about calibrating it.

So following the setup wizard in the hardware calibration menu I set the calibration up but didn't set a take off mark as I have no idea were it will need to go.

First conditioned the brake pads per Matco brake instruction. Then came the time to warm the engine up and do a full power run up at operating temperature. My max rpm was 5100 rpm with the prop set at 71.4 degrees. This is too high and out of range. So I added 0.3 degree of coarseness to the pitch and reran it. This time I had 5010 rpm which is in the acceptable range. During this process I also went out to the compass rose and calibrated the magnetometer.

After removing the cowl and inspecting the engine I found some wear on the cowl from an exhaust spring. So I rotated the spring 180 degrees and put some RTV on it. Also put a aluminum foil patch over the wear. If this doesn't solve the problem I will need to reform a deeper impression in the fiberglass.

Removed the gascolator and cleaned the screen. Then Safety wired it back in place.

Next came the mapping of the fuel gauge. Sorry no pictures. Basically I pumped the system dry and then added 2 gallon at a time and told the EFIS system of each addition. Then at 4 gallons I also checked that the "NO FLY" indicator was in the correct spot in the mechanic fuel gauge. After that continue adding fuel up to 16 gallons were the electric gauge won't read any fuller. Followed the guide lines in the RV-12 Acceptance Procedures as it is required to roll the plane up on blocks and then off at certain time in the process.

8/13/15: Closing thought: I received word from Gary Brown the FAA accepted my paperwork and we scheduled for the inspection. Also I am schedule at the end of the month for transition training with Mike Seager. This project is finally winding down after 4 and a half years.

Tuesday, August 11, 2015

Vans Aircraft RV-12 Airplane Build: Final Assembly (part 15) Final EAA inspection

Reference: Page 11-09, 33-02, 35-05, 37-10, 42N-20

In preparation for the Final EAA technical inspection I installed all of the inspection panels, cowl and the interior. Thus all of the reference listed above. Also I didn't take many pictures today.

First came the weighing of the airplane. Wait for it... total 763.8 pounds. Heavier than I hoped. Next Ernie showed me how to sync the carburetors and set the idle. Running it through the various RPM upto 3000 rpm. Below is the tool he used to sync the carbs and hose hookup.

Last but not least we safety wired the throttle nuts.

After all of this Ernie left me to finish the measuring for the weight and balance.

Finished up the measurements and calculation and submitted the paperwork to Gary Brown who is a DAR here in Oregon to get my DAR inspection. I'm not going to go into detail of how to complete the paperwork because I think this varies a little from region to region. As the old saying goes "your milage may vary". So talk it through with your DAR or FAA examiner.