I'm still buggered by those six little screws that have been taunting me since the last page of Section 21. It looked so easy! Just put six screws up through the belly skin and attach them in place with six little lock nuts - how hard could it be?
The first sign of difficulty came when I couldn't reach both the screw head and the nut on the other side of the skin at the same time. That's when I knew I was going to need help. That should have been easy too, but I soon learned that the help available to me within the family was not up to the task. The nuts are pretty tight on the screws and try as she might, young Co-pilot Egg simply couldn't hold the socket wrench tight enough. I enlisted outside help, but it was quickly determined that part of the problem was the insufficiency of my tools., The socket I had was too shallow to allow the inch long screw to be fully threaded onto the nut. The suggested alternative was to go to Harbor Freight on a procurement mission for nut drivers. No problem, that, since I also needed a tube cutter for the pending fuel line work.
Harbor Freight did have nut driver sets, but none of the sets contained the required size. The nuts in question are a relatively exotic 7/32" and the Harbor Freight nut drivers skipped from 3/16" (6/32" for those of you that need a translation) to 1/4" (8/32") with no intermediate stop at 7/32". While the sizing of all Harbor Freight tools is somewhat approximate, I didn't think I could count on a convenient 1/32" spread, so it was off to Sears, Home of Precisely Sized Yet Onerously Expensive Tools. It wasn't all that bad, as it turned out. $3.79 for a deep well 7/32" socket. I wouldn't want to buy a 64 piece set at those prices, but it was okay for a one-off.
With the nut now held firmly in place with the Craftsman Unaffordium socket wielded expertly by a manly helper, there was only one other possible point of failure: the screw head itself. Which is, naturally, where the next healthy application of FAIL came from. The fit of the screws through the nuts is so tight that the screwdriver finds it easier to just eat away at the screw head than to torque the screw into the nut. We managed to get two of the six installed, had to use the Dremel to cut two partially installed but completely ruined screws out of their holes, and ruined the remaining two screws in abortive attempts. I now have replacement screws and nuts on order from Van's, along with a preemptive order for more fuel line because I'm pretty certain how well that job is going to go too.
In the meantime, I placed a request for helpful hints on the Vans Air Force web forum. To date the best reply is "tap the nuts with an 8-32 tap first to loosen them up," followed closely by "use Loctite to keep them fixed in place if you do."
That sounds like a workable plan.
Showing posts with label Page 21-20. Show all posts
Showing posts with label Page 21-20. Show all posts
Sunday, June 27, 2010
Wednesday, June 16, 2010
One of those days
Some days I have the Midas touch. Some days I don't. And some days, well, I suppose the opposite of Midas would be the merde touch. It's French - Google it. Today wasn't quite that bad. I think I'm going to go with the petit merde touch.
It started early. I arrived at the paying job at my normal 0615 and settled in at my desk after a brief stint brewing the coffee and yelling at the newspaper. I had left a job nearly done yesterday afternoon and put the finishing touches on it this morning. It's a clever piece of code that goes into the database and retrieves an entire hierarchy of data. In other (equally opaque) words, it retrieves a top, root object, then retrieves the children of that object. As it retrieves each child, it also retrieves their children. If you were to draw out the relationships, it would look like an org chart or family tree. The benefit of getting everything all at once is that I can get at the entire family, if you will, after just one operation against the database. Efficiencies are gained by doing so.
Well, efficiencies are gained by doing so if (and only if) it actually works. It didn't. Instead of returning my happy family of data, the program crashed with a stack overflow. What that means in a nutshell is that my computer ran out of memory. With the kind of memory computers have these days, though, that would have had to have been one very, very large family. No, it meant that something was horribly wrong in my code.
It came down to a problem with cousins, to drag the familial analogy along even further. After quite a bit of hair pulling and desk pounding, I realized what was happening. When I was creating one of the children, I had it also create its own children. As long as I was doing that, I thought I'd be clever and have it create a somewhat unrelated relative that I thought might come in handy later. You know, as a kidney donor or something. I'll call that new relative a nephew - it's nicer than "parts bank."
The problem was that the nephew was never intended to be included in the family, so as part of his creation he had to find out who his uncle was to maintain at least some semblance of association. So, when the uncle created him, he in turn tried to create an uncle for himself. That uncle tried to create another nephew, who also tried to create an uncle, who tried to create a nephew..... On and on and on, until there's no memory left to hold it all. Stack overflow, scream of frustration, pound the desk. You know it's bad when coffee is the calming influence on your morning.
I doubt if that made much sense, so suffice it to say, it was all quite frustrating.
Once I figured out what the problem was, it was easy to fix. I neutered the uncle. Serves him right.
Unsurprisingly, my work on the airplane tonight ended in frustration. Not the screaming, desk pounding kind. More of an "Oh well, it's just been that kind of day. It will look fine tomorrow."
It was to be a light night. All I had left to do in the seemingly interminable Section 21 was to rivet on the very last bulkhead. It took four nutplates and 16 rivets, plus a detour into the second of the two autopilot brackets, but it was pretty easy.
Being as this is pretty close to the end of this section, I kind of took an audit of completeness, as it were, basically just trying to see if I had missed anything. Here's a bit of a mystery:
It started early. I arrived at the paying job at my normal 0615 and settled in at my desk after a brief stint brewing the coffee and yelling at the newspaper. I had left a job nearly done yesterday afternoon and put the finishing touches on it this morning. It's a clever piece of code that goes into the database and retrieves an entire hierarchy of data. In other (equally opaque) words, it retrieves a top, root object, then retrieves the children of that object. As it retrieves each child, it also retrieves their children. If you were to draw out the relationships, it would look like an org chart or family tree. The benefit of getting everything all at once is that I can get at the entire family, if you will, after just one operation against the database. Efficiencies are gained by doing so.
Well, efficiencies are gained by doing so if (and only if) it actually works. It didn't. Instead of returning my happy family of data, the program crashed with a stack overflow. What that means in a nutshell is that my computer ran out of memory. With the kind of memory computers have these days, though, that would have had to have been one very, very large family. No, it meant that something was horribly wrong in my code.
It came down to a problem with cousins, to drag the familial analogy along even further. After quite a bit of hair pulling and desk pounding, I realized what was happening. When I was creating one of the children, I had it also create its own children. As long as I was doing that, I thought I'd be clever and have it create a somewhat unrelated relative that I thought might come in handy later. You know, as a kidney donor or something. I'll call that new relative a nephew - it's nicer than "parts bank."
The problem was that the nephew was never intended to be included in the family, so as part of his creation he had to find out who his uncle was to maintain at least some semblance of association. So, when the uncle created him, he in turn tried to create an uncle for himself. That uncle tried to create another nephew, who also tried to create an uncle, who tried to create a nephew..... On and on and on, until there's no memory left to hold it all. Stack overflow, scream of frustration, pound the desk. You know it's bad when coffee is the calming influence on your morning.
I doubt if that made much sense, so suffice it to say, it was all quite frustrating.
Once I figured out what the problem was, it was easy to fix. I neutered the uncle. Serves him right.
Unsurprisingly, my work on the airplane tonight ended in frustration. Not the screaming, desk pounding kind. More of an "Oh well, it's just been that kind of day. It will look fine tomorrow."
It was to be a light night. All I had left to do in the seemingly interminable Section 21 was to rivet on the very last bulkhead. It took four nutplates and 16 rivets, plus a detour into the second of the two autopilot brackets, but it was pretty easy.
It's passingly odd that there are no bushings in those holes. I went back through the plans and could find no steps instructing that bushings be installed there, so there it is. A mystery.
The second to last step is the installation of a bracket that will support the fuel flow sensor for the Dynon D-180. This sensor will measure the flow of fuel (hence the diabolically clever name) through the fuel lines, allowing the Dynon to display the rate at which it is being burned by the engine. Useful, that.
The bracket goes down in the tunnel between the seats.
It's kind of hard to get at down there, which is unfortunate since it has to be match drilled to the belly skin. The long #30 bit is required.
Once drilled, the bracket had to be removed for the installation of (what else?) two nutplates. That done, I clecoed it back into place and prepared to rivet it in. Looking down into the tunnel and thinking about how hard it was going to get to get the rivet puller down there was a little depressing. Frankly, it was a battle that I did not want to fight. Suddenly it dawned on me that not only would I not need to fight that battle, it would have been foolish to do so. Who wants the wart looking pulled end of a blind rivet hanging out of their belly skin?? No one, that's who! Not even when it's airplane skin we're talking about and not their own skin!
The right thing to do would be to install the rivets up through the belly skin. There's no easier time to choose do the right thing than those rare occasions when the right thing is also the easy thing.
Well, if not easy, at least easier.
So, last step. Looks easy: install six panhead screws up through the belly skin to act as attachment posts for some device to come later. Six screws, six metal locknuts. Nothing to it, right?
You know what they say are the three most important aspects of real estate are, right? Location, location, and location. These screws are not in good locations. Not.At.All.
After futilely struggling with the first one for twenty minutes, a thought struck me: this is the easiest one.
I uttered a sharp, non-petit "Merde!" and called it quits for the night.
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