Monday, November 19, 2012

And now we wait...

I've been plodding along on my acceptance testing with no great sense of urgency because, well.... it's out of my hands. Yes, another open-ended, unforeseen delay. 'Tis the nature of the game. This time it has to do with the landing gear. One Service Bulletin has already been released by Van's that has grounded the fleet until such time as some inspections and adjustments are made to the way the landing gear legs are bolted to the center section of the fuselage. Those of us still building are furthermore even more firmly enmeshed in the problem in that there is a special directive aimed at us, the Reader's Digest version of which can be encompassed in a single word: "STOP!"

 The latest update from the factory is that they have developed a small parts kit comprised of some skin doublers that will have to be riveted to the sides of the airplane. Unfortunately, the couple of hundred rivet holes that the doublers will be riveted into already contain a couple of hundred rivets on my particular plane. Those will all have to be drilled out in order to install the new doublers. I haven't talked to the FAA guys about this - I suppose that it's possible that they would go ahead and do the airworthiness inspection even with outstanding Service Bulletins, but I kind of doubt it. In any event, I'm waiting. Which isn't to say that there is nothing to be done while I wait. It's more the case that what there is left to be done is not sufficient to fill the available time, so I've just been dabbling at it. Which means more time to play with Cabot!

And his friend Buster:

The acceptance inspection has things coming on and off of the airplane at a prodigious rate. The lower spark plugs needed to come out for one part of the inspection and I was a little concerned about the difference in the look of the plugs between the front cylinders and those in the back two cylinders.

This is apparently common to the Rotax, so it was an unwarranted period of angst. I'm having a lot of those, lately.

Van's wants us to test the sanctity of the pitot-static system which is, of course, a laudable directive. Thet said, their chosen methodology was not very confidence inspiring. Slipping a syringe over the pitot tube and holding it while testing the leakage rate was nearly impossible without tainting the results with uncontrollably small changes in the pressure from the thumb holding the plunger. 

It was accurate enough to detect a massive leak in the pitot system, though, which I (not very) quickly tracked back to a problem that I had encountered when putting the pitot fitting into the ADAHRS box.  See the threads showing on the fitting on the left? Yeah, that ain't quite right. The thing is, it was as tight as I could get it without risking breaking something. I ended up taking it back out and putting a very, very small dab of Boelube on the threads. That made it screw back in without the discordant resistance. It sounds easy now, but a lot of hours were spent on this operation. 

Testing the static system was better, but not by much. The way that is done is to tape over one of the ports, then use clay to form a seal around the syringe and the other static port. This too was a completely imprecise method and it took quite awhile to get comfortable with the results. Which isn't even to mention the concern over getting modeling clay into one of the static ports.  

Then it was time to remove the gascolator to check the internal filter for obstructions that may have flowed down from the fuel tank. The location and design of the gascolator makes this a burdensome job. Getting it off of the plane was bad enough, but replacing the safety wire when re-installing it was an exercise in frustration. The first effort was sub-par and despite the strong temptation to just leave it in place I ended up re-doing it. Knowing that I'm going to have to do this every year for the rest of my life, well, that's not the happiest thought right now. Especially when you consider that the filter screen was impeccably clean.

Having exhausted all of the little things, I moved onto the weighing. The first step is getting the airplane level before it even goes on the scales. The idea is to place a line on the hangar floor that gives a consistent measuring point from which to determine how far aft each axle is. You would think they would be identical, but one of mine ended up being a half inch further aft than the other. 


Van's has us put the main wheels on 2" thick blocks, then add or remove air from the nosewheel to get the plane level.

Two amazing things happened when it came time to plumb the spot on the floor. 1) I had a plumb bob. 2) I was able to find it.  Amazing!!

Once the requisite measurements are recorded, the plane goes up on the scales. I accomplished this via an inadvisable method: I got under the wing and lifted it with my back while Pete slid the scales and block under the wheels. It ended up requiring that nearly all of the air be let out of the mains (not the nose, as expected by Van's) to get the plane level. 

The final result was 701 pounds. Which considering that a more typical weight is 726 pounds sounded wrong to me. Very wrong.  

I stewed about it over night and decided that the only recourse would be a re-weighing. Having had a night for my back to register quite strident complaints about my lifting method, I decided to use a slower yet decidedly more back-friendly approach.

Thinking that maybe the extremes that we had to go through to level the plane with the 2" blocks had adversely affected the precision of the weighing, we didn't use them the second time. By releasing equal pressure from the left and right mains, we were able to get a nice level. The results were much more realistic at 719 pounds (the picture shows 718, but the two little side panels that close the fuselage sides at the top of the landing gear legs aren't installed and the number on the scale was bouncing between 718 and 719 indicating something between 718.9 and 719.0). The 719 value stands favorably against a 726 pound airplane that has the lighting and/or interior kit(s) installed.

There are a few more inspection things to be done, the paperwork needs to be gathered and sorted into a presentable package, and I have to find someone to engrave the data plate. After that, it's just a matter of waiting.

Tuesday, November 6, 2012

Blind Spots

Some lessons just need to be learned over and over and over, or so it would seem. I thought I had a pretty good handle on my propensity to develop blind spots. As evidence I point to the fact that despite taking the sixteen hour course that will permit me to sign off the annual condition inspections on N284DG, I intend to continue the practice of paying a local AP/IA to take a look at it once a year just as I've done every year that I've owned the RV-6. I think this is a prudent thing to do, especially after he found a crack in the elevator trim tab that I had to have looked at hundreds of times, but never saw.

It happened again with the CHT problem. After getting some hints from Van's on what to look for in my quest to isolate the problem, I asked Pete to come down to the hangar and help out. It's much easier to trouble shoot wiring when there are a couple of people working on it - someone has to hold a multi-meter probe at each end of the questionable wire and with a long wire, that can be difficult to do alone.

As we were looking around at various wires to test, Pete asked about a PURPLE/YELLOW wire that was hanging loose from the wire bundle. I had seen that wire before, but because I was looking for a PURPLE/BLUE wire, and because it is not uncommon to have cut/stubbed wires on a Dynon D-180 to Skyview conversion, I ignored it. I ignored it even after learning from the wiring diagram that I was, in fact, very interested in the condition of PURPLE/YELLOW wires. In other words, I was looking right at the problem, but a blind spot that I had developed it was precluding me from actually seeing the problem.

Sure enough, fixing that broken wire fixed the CHT problem.

Man, did I ever feel like an idiot!

It's fixed now, though, and we can press on with the next items on the to-do list.

I'm not sure why the wire broke in the first place, and that's going to nag at me for awhile. I do have a theory: that particular bundle is the only one that doesn't seem to have enough slack. In fact, it seems that there is quite a bit of stress on it. I think it's possible that starting the engine introduced enough vibration to simply rend the wire in half.  I'm going to have to find a way to relieve the stress on the bundle so this doesn't happen again.

Monday, November 5, 2012

Getting back to work

I'm sure you've been wondering... 

Why haven't I been posting updates on my progress? Because there really hasn't been much. There are a number of reasons for that.

The weather has, of course, been miserable, and so have I. Regarding the weather, I really shouldn't complain. Yes, it's been cold and windy, and it's getting dark ever-so-early these days. Yes, I am frustrated that young Cabot Bennett, of whom I do not expect a tremendous amount of intellectual acumen, remains convinced that I can summon forth light and heat at will (and to be fair, from his inside-the-house perspective, I can!) so that we can go outside and play but simply choose not to.  He is immutable in his belief that if he stares at me with big, sad, plaintive eyes long enough, I will exercise my god-like light-creating gifts and we can go outside for some fetch.  Yes, these are weather-ish frustrations, but they are nothing compared to what's happening out east.

But still, they are my frustrations. So, they matter.

Nor did it help that I somehow ended up with godawful muscle spasms in my neck and shoulder.  Bad, they were, and not conducive to any productive activities (such as throwing a ball for the dog). They were far more conducive, as it turns out, to sleepless nights and an extremely edgy mood. ("Go AWAY, Cabot!!")

This continued well into the work week.  I finally broke down and made an appointment with my chiropractor. I have to say, I think I really impressed him this time. He poked and prodded around the neck/shoulder area for longer than usual, and finally proclaimed his diagnosis:

"Oh, my!"

Yeah, tell me about it! He did what he does to get the bones back into their proper places ("Two vertebrae and a couple of ribs - what did you DO??") and started trying to work the knots out of the spasming muscles. He found one particularly bad spot (I can how badly the muscle is clenched  by how much it hurts when he presses on a spot , and this one hurt a lot!) that he started working on. 

"It feels like you swallowed a golf ball!"

I should be so lucky. Ipecac is dirt cheap compared to this guy.

After a better night's sleep and a dose of muscle relaxant, I was pretty much, almost, more or less, maybe, back to my normal contumacious and surly self.  For awhile. Things are pretty weird at the office, though, and I'm in one of those phases where everything I touch turns to, well, something worse than when I started.

A couple of days ago I was frazzled from a morning of enduring the irritating shriek of those blasted motorized weed blowers that had been running outside my window all morning, I tried to escape for a little peace and quiet at a nearby Chinese restaurant, only to get to my pretty little car waiting for me in the parking lot and see its grill stuffed with hundreds of leaves blown there by the Professional Leaf Blowing Squad from South of the Border.


I got to the restaurant and settled into a booth. I was just getting started on reading my book (more on that later) when what do I hear? Yep, another trio of motorized leaf blowers working their way down the sidewalk outside the restaurant. Just as they reached the door, another pair of customers opened it to come inside. So in addition to now having to endure the unadulterated screaming of those cursed things, I also got to enjoy the cloud of noxious fumes that blew in with the recent arrivals. Who, as it turns out, sat down at a table right next to me and started to have a heated argument about the pros and cons of using the default record ID versus creating a proprietary new one.

In other words, geek talk.

Not just that, but heated geek talk.

“I would most wholeheartedly argue against that approach!” one of them said in what passes for vehemently in geek circles.

It was like overhearing a pair of ninety year old English butlers arguing over the merits of two-minute versus three-minute basted (“No, my illustrious friend, I will fight to the veritable death to prove that anything cooked longer than two minutes is poached!”) eggs.

As to the book. It is the story (told in first person) of a woman who has a friend who is having an affair and shares the secret with her. This causes her to reflect on her own comfortable yet unexciting marriage to (wait for it….) an IT geek. 

Hey, it was free.  You get what you pay for on Amazon. And it's supposed to be a murder mystery, but the only thing dying so far is my interest.

Anyway, she decides to “re-sexualize” their marriage, but continues to run into difficulties along the way, thus making her more and more frustrated. The husband has to work late and comes home too tired. He goes golfing in the morning and comes home in the afternoon, having invited another couple over for dinner. This naturally stymies her Saturday night plans for which she had gone to the pain of buying some nice, uh, intimate clothing at Victoria’s Secret. 

And somehow this is all his fault!! 

This bothers me no end. This is the biggest problem men have with women. Listen, we’re not fricking mind readers. We don’t have brain scan modules implanted in our frontal lobes moments after circumcision. If you want us to know something, TELL US!!! Especially if it's uh, you know, that kind of thing. Trust me, we're all ears when it comes to THAT!

And then…. A new arrival came through the door (quietly this time) and plopped down in the booth behind me, where he commenced to have a profanity-laced cell phone conversation. It finally wrapped up just as I was surrendering the game and getting ready to leave, figuring my office would be more relaxing than this had turned out to have been.

“Yeah, dude, we just gotta keep on keepin’ on.”
I wanted to shove my fortune cookie down his throat.

I did manage to get a couple of things knocked off of the RV-12 to-do list, though. First and foremost, the airplane moved under its own power for the first time!  I finally was able to re-do the engine run that I had to abort the last time I tried due to the loose valve covers. It was a little chillier this time around so I had a good ten minutes of sitting at idle waiting for the oil temperature to reach the requisite 122 degrees. While I was waiting, I spent a little time messing around in the Dynon SkyView EMS setup pages trying to get the fuel pressure gauge to work. The sensor mapping page showed the 'Kavlico 0-15 psi sensor' as having been detected and functional, but it was displayed in a bright red font. That font selection could only mean one thing: "SOMETHING IS WRONG!"  I noticed that the sensor didn't have a setting in the column next to it that displays what the SkyView thinks it should be doing with this sensor. I played around with the menus until it said 'PRESSURE', or something like that. I'll have to go back and get a picture of it. The net result was that the fuel pressure started indicating on the Dynon screen. Score a point for my side!!

The right side CHT was still showing a big red FAIL X, so it wasn't a complete victory.

The oil finally reached a decent operating temperature and Pete was not gesticulating wildly about anything amiss in the realm of leaking fluids, so I ran up the engine to wide open throttle. The RPM topped out at 4,750 rpm, so the prop angles will need to be adjusted to find an additional 200 RPM.  The good news here is that the brakes held the airplane at bay even at full grunt. That gets a checkmark on the acceptance test sheet. Figuring I had the motor warmed up and proven useful brakes, I had Pete pull the chocks so I could taxi around a little bit. It drives like a dream!

After the engine was shut down, I pulled the panel off of the avionics bay. Pete and I teamed up to test the continuity of the BLUE/PURPLE wire that runs from the CHT-R thermocouple post on the engine up to the Van's J-Box in the bay. Dead as Kodak's business model. Or so I thought. Pete took a look and pointed out that I was testing the wrong wire. I was testing the BLUE/PURPLE wire that comes out of the J-Box and plugs into the Dynon EMS module hanging on the firewall. As he pointed out, we really didn't know for sure if that was the correct wire. Just being the same color code should be enough to know, but given Van's demonstrated proclivity for practical jokes, it wasn't.  I removed the connector that provides the input to the J-Box and tested the wire there.

It was good.

Damn. That means the problem lies somewhere out of my purview.  It's either a Rotax, Dynon, or Vans problem, and of those three, Dynon is simultaneously the least likely to be the culprit and most likely to be helpful in troubleshooting. I decided to start with Vans.

As I sat on hold waiting for someone to answer, I couldn't help thinking "I hope it's not Ken. I hope it's not Ken." I'm still a little bitter after having to argue over whether or not they had sent me a $.75 adaptor plate. I said they hadn't, he said they had because "they made a pretty good guess as to who would need one."  He said that I probably had just lost it. Now, we all now that it is more then possible for me to lose something; history is on his side there. But here's the thing: I know when I've lost something. I remember actually having  had it, I just don't know where it is.

So, a few minutes later my call was answered. I explained the problem, I explained what I had already done to troubleshoot the problem, and I ended with, "I don't know what to do next."

"Neither do I," was the response.



After a brief pause to swallow my first response, I said, "Well, why don't we try to figure it out together."

That worked. From that point on it was a professional and moderately helpful call. He suggested testing the continuity through the J-Box and up to the Dynon EMS module. To do so, he said, I should consult the wiring diagram on the Van's website.

Fair enough, but I couldn't help thinking that I already did that. Sort of, anyway.

So I pulled up the wiring diagram. I traced the BLUE/PURPLE wire up to the J-Box on the diagram. It was right next to the YELLOW/PURPLE wire that comes from the left side.  Coming out of the J-Box, the right side CHT is YELLOW/PURPLE, and the left side is BLUE/PURPLE.

Pete was right.


And so was I, in a way: another practical joke! What other explanation can there be for transposing those two wire colors??!

Hopefully I will be able to get out to the hangar while the good weather holds to check the rest of the continuity path. The goal at this point remains the same: figure out which of the four players owns this problem.