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Cozy MKIV - Chapter 21 - Yet Another Oaf Story

Screwing up the Right Fuel Tank

Start Date: August 13, 1998

Our local oaf has been slacking off lately, due to some problems he's been having which have depressed him no end. Since he's just recently come outof his slump, I think the time has come to tell his latest tale.

Once upon a time, there was this oaf (same oaf as the one from Chapter 9 and Chapter 18 - I mean, how many oafs [oaves?] can there be in Acton, MA building COZY MKIV's?) who was still (after almost 4 years) building his plane. He had just built a new cottage (2x6's, 25 year shingles, etc. - no straw or sticks for this oaf) with a two car garage, so he could actually do the assembly of the aforementioned plane. After the standard time spent arranging furniture and installing shelving, the oaf went back to work on the important stuff (the plane).

To make a long story short (well, shorter - nothing having anything to do with this oaf is ever short), while working on Chapter 21 (strakes and fuel tanks) the oaf got to the point where he had the right bottom strake glassed in place with all the ribs glassed in as well. He had installed all of the fittings, the fuel sender unit and fuel cap (in the right top strake) as well as the sump and fuel lines. He had used the "T-hat" method to cap off the ribs with 1" wide BID strips, and had epoxied the inside of the bottom and top strakes multiple times to ensure sealing. He was just about ready to flox and glass the top strake in place (he thinks to himself).

It was at this juncture that the oaf's brain ceased to function at any point above his medulla (and there just barely). Whether this was due to cosmic rays, the phase of the moon, Jupiter being in conjunction with Neptune, or a spell cast by our now all too familiar witch, who can say... maybe there's just a good reason our hero is called an "oaf".

So, with the oaf's body operating on autopilot (and one not nearly so good as the Navaid the oaf is installing in the plane), he floxes all the "T-hat" sections and strake rim, paints epoxy on all the mating surfaces, and then puts the strake top on the strake bottom. "Hmmmm", the oaf mumbles to himself - "did I put enough flox on there? I didn't see a whole lot of squeezeout in a few places, even with all the weight on the top".

For all of you following along out there, this right here is the critical decision point - watch carefully how our oaf screws up.

"Well, if I take the strake top off to check, I'll probably find that everything is OK, and then it'll take me another hour to re-apply the flox and put the strake top back on. What a waste of time THAT will be. I'll just assume everything's OK, and let it cure".

The oaf can, in retrospect, hear all of you screaming "No, you dope! If you have any doubt at ALL, check your work!!!". However, we must remember that the oaf's brain was turned off as he was performing this task, making it impossible for him to see even the most rudimentary of intelligent moves.

Anyway, the oaf eventually gets around to pressure testing his tank, and lo and behold (all fairy tales have a lo and behold in them) it leaks like a sieve. The oaf quickly finds a large leak at the joint of the TTE bulkhead, the main spar and the strake top, and after butchering the strake top fixes it (or so he thinks). This cuts the leak rate down by a factor of four, but there's still another leak which he finds at the joint of the inboard diagonal, the fuselage side and the strake top. Bada bing, bada boom, a little flox and BID, and that one's fixed too.

Our oaf thinks everything's alright now, but little does he know that having his brain off for that critical 5 minutes will now cost him about 3 months of untold misery. While the major leaks are now fixed, the oaf still has a residual leak that causes the tank to lose 18" of water pressure or so over a 4 hour period. The oaf starts putting soapy water all over the place, and finds some small leaks around the fuel cap (fixed with some lithium grease on BOTH O-rings) and around the electronic fuel sender unit (fixed with some gasoline-proof gasket sealant).

This reduces the leak rate by half, but it still leaks. Our despondent oaf stops going into the garage on a regular basis, and takes to berating his wife and son unmercifully for no good reason. The oaf's wife, being a saint, doesn't chop him into small pieces and feed him to the squirrels during the night, but lets him get back to the garage as he will.

The oaf keeps painting soapy water on every possible surface, including all the vent lines that he's plugged up, but can't find a dang thing -"what's the air doing - osmosing through the fiberglas?" he thinks to himself, knowing that can't be the case.

Eventually, the oaf decides to fill the tank up with water to see if by tilting the tank in various directions he can locate the position of the leak. However, when he does this and pressurizes the tank, the lack of flox on the top rear of R33 causes the strake top to explosively depart company with R33. The oaf's wife says "yo, dude, that didn't sound good" when she hears the large "BANG". "No" our hero replies, "that sucks - I just broke my plane".

The oaf now takes a hacksaw and cuts a 16" x 8" rectangular hole in the top of the strake centered over R33, and finds that there was a total of 3/4" of flox connection between the two parts out of a total length of 14" or so. Gentle reader, go back to the paragraph where the oaf said: "did I put enough flox on there? I didn't see a whole lot of squeezeout in a few places, even with all the weight on the top".

So, is this guy a moron, or what?

ch21_repair.jpg (14968 bytes)Our oaf now patches the strake top back in with appropriate glass layers, fixes a small leak near the rear of the cutout created during this patch and goes back to trying to find the leak. He fills the tank with water, tilts the nose up to get the water to the back of the tank and then pressurizes the tank to 18" of water pressure. Hmmm, the leak rate seems substantially slower now - maybe our oaf has covered the leak with water so the air can't escape. He finds a fine-tooth comb in his overalls and goes over every square inch of the strake. With the strake top still butchered from the first gross leak fix, the oaf notices a tiny drop of water growing larger near the aforementioned TTE, main spar, and strake top.

Believing himself close to resolution, our oaf grabs his Dremel (actually Ryobi) tool and grinds away at the suspected leak area. He chases the leak down along 6" of strake top until he gets to a point where he's got a stream of water being ejected from a tiny hole in some flox. "YES!!!", our oaf thinks. He drains some water from the tank, dries everything off with paper towels and a hair dryer and then epoxies, wet floxes and 2 BID's the hole, while pulling a 12" water pressure vacuum on the tank all the while.

Our oaf lets this cure and then re-pressure tests the tank for what seems like the 3x1017th time. Our oaf now finds that the tank loses 1" of water pressure in the first 24 hour period - approximately 2 orders of magnitude less than before. He also finds that the tank pressure stabilizes over the next 24 hours, even increasing in pressure as the temperature rises during the day. This is enough to make the oaf believe that he's really cured the problem.

Now, I won't make the claim (as the past two times) that this oaf's story has anything resembling a happy ending - I'm not Voltaire and I don't subscribe to the theories of Dr. Pangloss. However, the oaf can, at least, progress to the left strake and the reader can rest assured that the oaf will NOT repeat this same mistake again (no matter what the witch does), although the oaf does seem to have a bottomless pit of new mistakes from which to draw at any given time.

If, however, this story prevents even one reader from doing anything resembling the same stupid thing by giving them the magic spells with which to resist the evil castings of the witch, it will have been worthwhile to relate it.

End Date: November 1, 1998


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Copyright 1998, All Rights Reserved, Marc J. Zeitlin
email: marc_zeitlin@alum.mit.edu