Sunday, April 1, 2012

Bereft of Sanguinity

Regular readers will have no doubt noted the uncharacteristic lack of prolixity hereabouts over the last week; it had been one of those weeks where both the paying gig and the airplane building have provided higher than normal levels of mental stress.

Yes, in one place I have trouble, trouble with a capital 'T' which rhymes with 'D' which stands for 'Data.' It a long and involved saga, but eye-wateringly boring, I'm sure. Suffice to say, there are pressures that are brought to bear on the purveyor of bad news that, while short of a literal shoot-the-messenger model, are nonetheless unpleasant for the poor fellow tasked with presenting a fact-based analysis that throws a harsh light on an unsolvable dilemma. Alas, such is the dark underbelly of the commonly perceived Rock Star lifestyle of the IT Director.

After giving over the best part of my day over to that kind of work, heading out to the hangar, where I have trouble, trouble with a capital 'T' which rhymes with 'C' which stands for 'Cowling', well.... it's not as restorative as one might have become accustomed to. Still, it ain't gonna fix itself, so.... out I went.

The problem, for those that may not have been keeping score at home, was that the top half of the cowling was mating with the lower half of the cowling like a dog on a chicken, which is to say, not very well at all. Having inspected a completed and well-fitted cowling on an investigatory foray to the darkest regions of southeastern Ohio, I knew that there was at least one place on the bottom cowling that needed further trimming. I knocked that off of the hope (as in "I sure hope this works!") list early in the week.

The ridiculously faint scribe lines that are intended to provide the critical cut-line are damn hard to find without the aid of bright light or an electron microscope. Harbor Freight doesn't carry electron microscopes, so...

The extraneous material has been excised:

Pete stopped by and we made a detailed inspection of the periphery of both halves of the cowling, studiously ensuring that we had removed material right up to the very edge of the scribe lines, or at least those that we could see.

That improved things, but there was still a real problem at the front of the cowling. The bottom flanged area was pushing the overlapping edge of the top half away from a nice, flat fit. Close inspection showed that the fiberglass on the outer side of the bottom half was too thick and would need to be filed down.

That made all the difference! With the excess resin removed, the top and bottom fit together as tight as OJ's glove.

Wait, that's a really bad simile, isn't it?

With the two cowl halves at least temporarily fitting well together, I thought it might be a good idea to hurry up and get some matching holes drilled. There are three holes to be drilled on each side of the big hole that the prop spinner will cover. The build manual provides a drawing to show the location of the two inner holes, but the reference line that they show in the drawing bears no resemblance to any landmark on the actual parts.

I measured from the wrong faux edge on the first attempt, but perspicaciously probing Pete found a better way of finding the right location. He noticed that the hole should be somewhere near a tangent line drawn off of the cooling air inlet. Reversing from there, it was easier to find the ambiguous measuring point called out in the plans. In my defense, note that I also knew something was wrong because the location of my first proposed hole would have put the screw that will inhabit the hole behind the spinner, where it would have been impossible to install or remove without having to remove the spinner. No one would design a headache like that into an airplane, I figured.

Oh, also in my defense: the glove didn't fit.

I'm still using the hand drill for fiberglass drilling - it gives more control and it isn't that hard to drill through fiberglass anyway.

Once the two initial holes a drilled, there are a couple more holes and a big slot to be cut into the bottom half. The slot allows the cowling to slip past the nosewheel strut.

Have I mentioned that there are two major problems with the scribe lines? The second is that there are sometimes two of them. Crazy!!

When this happens, I just use the more conservative of the two.

I managed to cut myself again, this time against the serrated edge of the fiberglass. Figuring that we were just about done for the day, I made do with one of my patented field bandages, crafted in a MacGyver-esque fashion from paper shop towels and masking tape.

There is still a lot of fitting to do, but here is what the bottom half will eventually look like when installed on the plane:

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