Sunday, June 30, 2013

Closing Out Sections

Thanks to the timely arrival of another load of ProSeal, I was able to close out 3 open sections in the build manual that were in some way or another waiting for some sealant job to get done.
Before this weekend work started I was able to remove some more of the Blue Plague that was sticking to the tip of the right wing.

I forgot to take a picture when it was all off but it looks close to what you see above. Quite some scratching again, but nothing deep.

The last days were incredibly hot - even for Tucson. The monsoons are still not anywhere close and so it was a dry heat, and that's the only positive thing to say about it.

This was the sun setting on the last cooler days before the weekend, which is to say it only got to the lower hundreds.

Even the local animals (this one is a particularly young bunny that has not experienced another summer before) were struggling with this heat.
So I decided to get up before 5am each day to be able to get some work done outside without collapsing. Even then it was in the lower 80s.

It was time to mix the smelly ProSeal and get started on sealing the firewall - again. First a look at the beautiful sight of the installed engine.

Then I filled a syringe with ProSeal, in the hopes of making less of a mess, but as you can see, I still am not good at putting the stuff only where it is needed.

It worked much better on the side skins where I sealed the leftover rivet holes from the reinforcement angles. That is because I used blue tape with a slightly oversized hole punched into it as a template. After peeling the tape off I was left with a perfectly round seal.

I also sealed the rivet heads from riveting on the heater box. The manual did not ask for it but I do not understand why as these rivets are providing the same risk of letting gases from the engine seep into the cabin. Angles were too bad to get a shot at them though, so no photos.
This step completed section 54.

After the ProSeal task was done, I put the lower cowl on...

... (pretty, isn't it?)... and installed the SCAT hose, which completed section 49.

I also gooped up the penetration holes in the firewall that contain the cables and wires. I used red RTV for this and not the suggested firewall sealant. I was considering using the rest of the ProSeal but decided against it. If I ever need to pull a wire or want to add another one, removing the RTV would be easier than any of the other sealants. And this completed section 50.

The idea is now to leave the lower cowl on and to remove the instrument cover to finish up the pitot line plumbing. I will try to also install the Ts to plumb in the backup steam gauges at this point and then plug their ends. There is also a tad more wiring work to be done for the avionics which includes running the missing wire from the radio to the AV-50000 for the serial port.
Additional antennas for the PCAS, ADS-D and the APRS system that I will add are sitting in the shop and I think I might add those now as it will be easier to crawl into the tailcone without the tank installed.

Wednesday, June 26, 2013

More Vinyl and a Fuel Cap

I caught up with where I had exited section 37, the Fuel Tank section, and happily noticed (but only faintly remembered) that I had completed the leak test on it before. I was then even using a pressure gauge instead of porous balloon and that helped my memory a little bit. The next step before installing the tank in the plane (which will also require the use of ProSeal again which I am not ready for tonight),  was to drill a vent hole in the cap.
For this the cap has to get disassembled which also gives a good idea of how it works when it's put back together. The reason for the disassembly is not that you could right drill through it while it is still in one piece but to be able remove the vast amount of drill chips after you have done so. The ample use of fuel lube on the O-ring does not help that task either, so disassembly is the way to go.

This is how it looks when you are done with this step.

The instructions tell you that the hole in the bottom piece must not align with the hole in the top piece, and they certainly won't as the bottom piece has to be adjusted for proper tightening which requires it do be turned.

After this step and realizing that I was not ready for the tank installation, I went on to removing more vinyl from parts that scattered all around the patio. This time I worked on the wings or better, one wing - the one exposed to the sun.

Watch how little the part in the lower left corner changes (the far outmost part of the right wing):

It happens that this lower spot is being hit by the sun every morning when it rises over the mountain ridge. That was enough to make this piece deteriorate to the point where you cannot pull it off anymore.
I started scraping but it got too dark too quickly to really make significant improvement. More fun with it tomorrow evening.

Monday, June 24, 2013

Fuel Nozzle Modified

When I came home I removed the rest of the vinyl on the tailcone which was uneventful as most of it came right off or needed only a little persuasion.
So I went on to work on the fuel nozzle which I had put away since it was painted. The one thing that I did not like abut the planned installation was that it required the application of ProSeal only to then fiddle with tiny nuts to put on the screws holding the nozzle to the skin. That whole setup is supposed to get tightened only to the point where the sealant oozes out and then builds a seal when cured.
This is already a delicate and messy process and fiddling with those nuts wouldn't make it easier. Also, for future removal, it would require a second person inside the fuselage if the rear window was not supposed to get removed as well.
So, I decided to replace those nuts with nutplates, K1000-06 to be specific. Here's the picture documentation of this well know process.

This should make the ProSeal installation much easier and cleaner (fingers crossed!).

The Blue Plague

There is not much to report from this weekend's build process. It was pretty hot and the weekend was predominantly filled with alternative activities like early morning hiking and such, so there was only limited time to work on what I consider to eventually become a plane.
I received a few more parts for completing the build. Among them was the engraved N-number plaque and the gear leg and transition fairings that I plan to add after certification. As a matter of fact, I am planning to trim and install them before certification while I still have the plane in the carport as I deem this to be easier to do at home than at the hangar. I will remove the fairings for certification and then put them back on afterwards.

N-number plaque (about 2"x1")

One problem I ran into this weekend was a self-inflicted one that many had warned me about earlier. It wasn't an issue when I had first read about the Blue Plague and I thought then that these guys were just unlucky or received a bad batch. The issue is the blue vinyl that protects the sheet aluminum from scratches.
I had read that if left on, this vinyl would become a pain in the builder's behind to remove from said sheet aluminum, to the extend that many hours would eventually go into the removal.
Back when I read this, I had checked on my vinyl coatings and found them all pretty easy to lift off the surfaces still and I remember that I repeated this check about once a year during the build process. It was no issue until this summer and I assume this is related to me changing the position of the plane in the car port. I had pushed the plane backwards quite significantly late last year when I started installing the engine to get more room in the front area while working on the engine. That move caused the aft section to get almost pushed outside the carport and it was since exposed to the searing Arizona sun a lot longer during the days than ever before.
UV light kills any softeners added to plastics and the result was that on the areas that were exposed to the sun longest, the vinyl would not peel off any longer but only break off in small chips. That makes it almost impossible to remove the coating in a reasonable amount of time and I ended up scraping it off in these parts with the help of plastic scrapers and finger nails. This is indeed a very time consuming and rather frustrating work and this is when I remembered the warnings I had read years ago about the Blue Plague.
This is even more frustrating as I had decided to leave the majority of the vinyl on the sheet metal to protect it from scratches and then ended up creating much more scratched area due to the plastic scraper used to remove the protective coating than removing it early on could have ever left me with.

These pictures are taken AFTER the scraping. See the close-up on the left side and compare that to the right side which is still shiny as this side was less exposed to the sun.

The lesson that was learned from this is to not worry about scratches on the sheet metal and just remove it all at the time of riveting. It will look better in the end that way and with less buffing. Most of us paint the aluminum anyway and the sheet metal will get scratched up as a preparation for the paint, so there is no reason to be too protective.

With the help of my wife, we were able to remove the broken up patches of resilient vinyl from the tail cone in long scraping session and I will remove the rest on the frontal areas when I get home from the paying job tonight.
Also, the sealants all arrived and I patch up those rivets and holes on the firewall to seal them off in one of the next sessions.

Saturday, June 15, 2013

Engine Controls Completed

In the cooler morning (92 degF by the time I got to the carport), I went back to connecting the cables to the engine controls. And I immediately ran into an Oregonian Mystery. I followed the plans precisely and it was asking explicitly to re-use the locknut on the throttle arm that we had previously removed. It's the shiny, silvery nut in the picture.

Now this is a metric nut and I noticed that when tightening this nut, the bolt it was supposed to tighten was an imperial one (3/8" wrench). This worked for a bit until I tightened it a bit more and it turned pretty loosely all of a sudden. Also I had not noticed any resistance when I screwed it on and got to the locking section of the nut. 
Clearly this indicated that I had the wrong size nut and I just removed some of the threading (from the nut).

I tried an AN365-1032 stop nut and that went on with a much better feel and it tightened properly and the locking part worked as well.
I checked the instructions again and I could not find anything else than to re-use the metric Rotax stop nut. I think this is a mistake and I will post this in VAF later today. See the correct nut in the following picture.

The choke cable installation was pretty uneventful, just hard to get at on the right side for trimming it to the correct length.

Now, I just have to seal the grommet holes with firewall sealant or ProSeal and then I can mark this chapter finished.
I will let the RTV I used on the potential rubbing point between left throttle cable and oil hose for the pressure sensor settle and then tighten the double clamps that control the cables and also install the air filter on the left side.
Then it is back to finish left out steps. A lot will have to do with applying sealant which I would like to do all at once.

Friday, June 14, 2013

Cabling the Controls

I got home early today. Early enough to work a bit more on installing the engine controls. So I connected the cables to the engine and found a routing that should be causing minimum interference with sensitive parts like oil hoses and such. I also installed the slightly softer McFarlane springs on the throttle, replacing the Rotax original hardware.

It took me a bit to get this all set up because of not being able to find appropriate tools that would fit the hardware. I realized a bit late that this is metric hardware that caused me the troubles. Use a metric 10 wrench on the nuts of the throttle arm and a metric #4 allen wrench for removing the existing bolt attached to the throttle.
I have a slight interference between the left throttle cable and the oil hose leading to the pressure sensor and I will apply some RTV to it to avoid chafing.
After an hour I called it quits as it was a hot and slightly humid day that made working outside not very enjoyable. I will finish up tightening the hardware tomorrow morning.

Thursday, June 13, 2013

The Mysterious Engine Log Book

Before I ventured deeper into the ways of acquiring a replacement fuel hose from a Rotax Service Center in response to the SB 912-061, I browsed the good ship VAF for the experience of others in this matter.
I remembered that I had read about this SB shortly after my engine had been delivered last year and I found it here.
The interesting information that I took away from it was that some had this SB been taken care of before their engine delivery by some licensed mechanic through Van's or maybe the Rotax distributor and that such action had been noted in the Rotax Engine Log Book that they had received with the engine.
That made me feel very uneasy as I had absolutely no recollection that I had ever seen such a log book along with the paperwork that came with my engine. Unfortunately, I was at work when I had learned about this and I had to actively fight the urge to run home and check if my log book was missing (a 20 miles drive - one way).
When I got home I went through the collected stack of papers related to the RV-12 and, sure enough, I found the log book. You can really easily mistake it as yet another Rotax instruction manual as the shape and the cover page looks just like the service and maintenance manuals.

So I had put this important log book away with all the other Rotax documentation and never looked at it again for about a year.
Now, that I had learned that there might actually be an important entry in this log book, I opened it and found - to my big relief - an entry on page 5:

And that said that the SB had already been complied with and that a fuel leak test would have to be performed once the engine was installed.

So, there you have it. That was an easy job this time to complete this Service Bulletin!

Sunday, June 9, 2013

Controlling the Engine

I thought the next step was to finish the safety wiring on the gascolator but then I realized that I wanted to open the bowl and check for debris after the first engine run. I would have to cut that wire to remove the bowl and I think it is less than pure joy to put it on to begin with. So I decided to wait with the safety wiring until before certification day.

Instead of safety wiring I started on installing the engine controls, choke and throttle.

Sliding them into place was fairly easy to do. Getting those cushioned clamps in place was not. The help of some temporary tie wraps made this possible though.

Tightening the nuts on the back of the controls was again pretty awkward to get to. A wrench would hardly turn before it needed repositioning because of interference. This -12 is really hard to work on because of limited space. I sure hope this will all just stay in place forever.

Once everything was tightened down it looked pretty though and was well worth the effort (I guess that goes to say for the whole plane).

The firewall forward part had another surprise for me waiting. The job was to install a double clamp to keep the 4 cables from rubbing on any part of the motor mount. This thing put up quite a fight and I needed the help of tie wraps on both clamps and lot of creativity to get tools on both ends of the screw at the same time.
I think I probably worked half an hour on getting the nut installed on this double clamp alone.

I have not tightened it yet as I want to see how the attached ends of the cables affect the way they curve around the engine mount. Then it should be easy to finalize the position and tighten it.

So I first have to give these dangling cable ends a purpose before I can do this.

Saturday, June 8, 2013

Oil Cooler Fits!

I was so concerned about my modification of the oil cooler position possibly causing problems when attaching it to the cowl and installing the cowl.
Those concerns were not warranted as it turned out that wit a slight modification of the routing of the right oil hose that attaches to the cooler, the system fit perfectly.

It first did not look so good though when I first tried to fit the cowl on. I installed the cooler guides on the bottom cowl as the first step.

In this picture you see the conventional routing of the right oil hose.

With a lot of pulling and cussing the cowl finally slipped into place (or better, yet, was forced to do so). That looked only good from the distance.

On the bottom curves though you could see that the cowl was under a lot of tension and pulled to the left (or pushed, as it later turned out).

So what was causing this? There is so little room in engine area that I could not take a picture of the interfere nor could I myself see it. Bending my arm in ludicrous ways to get my finger tips to follow the oil hoses and feeling for possible contacts, I finally found the reason. The fuel spillover line installed as a patch to the need of Rotax installing a different mechanical fuel pump that vents fuel overboard in case of a malfunction, prevented the oil line from moving up where the oil cooler wanted to go.
This might only be caused by me moving the oil cooler about 1.5" forward as I also had to move it slightly higher than initially planned for. But the clearance would be minimal (if any) in the original position as well.
The reason the oil line is interfering with the aluminum fuel vent line is that the oil line is pointing about  30 degrees toward outboards with the original routing and therefore crossing the vent line. I saw that if I could persuade the line to attach straight from the aft to the cooler, that the line would then clear the vent line and had a chance to bend out of the way further aft.
I tried a few approaches before I finally settled on this one:

The only problem I saw with this routing was that the lower water hose is pushed slightly towards the exhaust and could possibly touch the spring after a while. I planned to apply RTV between the spring and the hose in that area.
There is now only a minimal push to the left as you can see by the oil cooler mounting holes being just slightly out of position.

With this setup the cowling went on almost as easy as before without an oil cooler and there was practically no tension on the cowl.

Before taking the cowl off for the last touches on the lower engine installation, I thought I should take some more shots of this pile of aluminum that now looks almost like a plane...

My wife helped to get some shots of the interior with the cowl still on to give you an idea of how much clearance my modification gave me between oil cooler and muffler.

You'll be the judge as to how vital this modification has been. Without the distance I moved this forward, I could have just squeezed a finger between the cooler and the muffler.

Once the cowl was off again, I finished section 48 (Muffler Installation) by filling the springs with RTV. While at it, I also applied some extra RTV between one of the right springs and the water hose to prevent it from getting contact.

Now this had to cure and so I decided to go back inside and escape the 100 degF it had reached in the carport by then.
I cannot find the description for the next step but I know that the screws holding the bowl to the gascolator have to get safety wired. So I will do that next and then install the bottom cowl and leave it on.
The next section is the installation of the engine controls and after that I could install the tank and fire the thing up.