Sunday, January 8, 2012


WATDI is another of my home made acronyms, just like classics such as the HVDFP (High Visibility Driving Finger Portal, aka 'sun roof') or VIO (Vacationing In Office, aka 'slacking off at work') - it stands for Work Avoidance Through Demonstrated Incompetence. The concept is simple: don't want to be put in charge of paying bills? Just bounce a couple of checks. Don't want to have to wash dishes? Break a few. Don't want to mow the lawn? Just run over one of the pets. See? It's easy!

I point this out as a warning, though. You see, if you ever want to mess up your hard-earned WATDI rating, build an airplane. Demonstrating sufficient ability to construct something that actually looks like a real airplane to the casual viewer makes it impossible to beg out of repair jobs at home. If you really want exacerbate the problem, fix a furnace. Do that and your Saturday mornings are going to be full of things like "Can you fix that slow draining kitchen sink? If you can fix the furnace, you ought to be able to...."

Well, that's not really how it happened. The right side kitchen sink had been draining slowly for at least a couple of years now, despite my repeated attempts to find and remove whatever obstruction in the pipes was blocking the drainage. Running the disposal would push the water out, though, so I just lived with it. Until Saturday; that's when it started gurgling in a skin-crawling sort of way.

It had to be fixed.

A little troubleshooting (by which I mean "noticing that there was a lot of food still in there") indicated that the inner grinding thingys of the disposal were welded in place with rust. Without the grindy thingys whirling about, food fragments weren't being disposed of, they were just being given a very exciting amusement park ride. After a lengthy period of ineffective grinding, the food bits just about clogged up the whole works. Easy fix: replace the disposal. Off to Lowe's for a replacement disposal, along with an impulse buy that would also need installing. We'd been looking for a new shower head and happened across just what we were looking for while hunting for the disposals.

The disposals Lowe's had were a little different than the one I had removed in that they had no plug-in cord and the fitting for the drain pipe did not have threads to take the fitting on the end of the drain pipe. The very knowledgeable Lowe's guy was able to gather up the extra parts I needed and save me from having to make a return trip. Yay, Lowe's!

Insult was added to the injury of my chore-laden morning when we returned from Lowe's to find the new fuel pressure sensor that had been sent by Van's. It was interesting to see how they're able to come up with small, low-shipping-cost boxes when it's them that's footing the bill:

If I had ordered the thing, it would have come on a cubic foot box and cost $28 to ship.

The disposal job would ultimately take only twenty minutes or so, a stellar performance that I attribute to the expert management of Mr. Cabot Bennett, seen here inspecting the work area for safety and dropped foodstuffs:

The instructions for installing the wire/plug were surprisingly comprehensive, comprehensible, and cogent - it was done in no time, as was the installation of the horizontal drain pipe.

It even turned out to be quite simple to get the new unit installed, the first time.

Unfortunately (and very characteristically), I had forgotten to put the threaded fitting for the drain pipe back onto the horizontal pipe. It all had to come back off to have the fitting re-installed.

The shower head should have been easy in comparison, but it took hours. What should have been a simple twist-off and twist-on operation was derailed by my inability to get the old head off of the pipe. Instead, I ended up accidentally unscrewing the entire pipe. That turned out to be okay - I was able to take it out to the hangar and hold it in a vise while I wrenched it off. The problem turned out to be a massive over-usage of Teflon tape.


A second problem arose when I screwed the pipe back in, using the normal one or two wraps of Teflon tape. When tightened snugly, the pipe was pointing up at the ceiling, not down towards the routine showering position.

Ah, that's why there was so much Teflon tape! I added a few more turns and tried again. A perfect fit.

This morning I was able to get out to the hangar to get back to work on the engine wiring. The first step was the installation of the fuel pressure sensor. It slips into the bracket on the firewall and gets an elbow fitting screwed into it. It's an odd installation, assuming that I'm doing it correctly, in that it fits fairly loosely into the bracket even when the elbow is tightened as much as I can get it. Perhaps the fuel hose is enough to hold it in place.

The next steps would have been horribly confusing had I not received the following missive from another builder that is working on the same steps I am:
Here’s my conundrum: The plans identify the WH-J48 as colored WHT/BLU, and the J-49 as BLU. Simple enough. However the Firewall Forward wire bundle contains NO blue wires. Nor does it contain any wires identified as “J-48/49”. Curiously, It DOES contain two wires of the same gauge as the wires in the WH-RV12 IGNITION (labeled as J-152/153**), that are the proper length, and come pre-terminated with the correct male pins, but they ain’t BLU – they’re both WHT, and only WHT. The only identifying marking on these white wires is a tag identifying one wire as “J-762” and the other as “J-763”.

Fast forward – through the process of elimination I skipped forward in this section and installed all remaining wires. All were accounted for and correctly identified, except the two WHT wires described above as J-762/763.

So I’m left with:
J-152/153** coming from the Ignition module,
J-762/763 coming from the firewall forward bundle.
No description as to who get connected to whom.

(Logic could dictate that J-152 marries J-762 due to the similarities of their identifying numbers, but I don’t want to take that chance with my ignition system)

**BTW – for what it’s worth J152/153 are also described in the plans as being BLU and WHT/BLU when in reality they too are both WHT. They do however contain an attached label identifying them by number.
I had the exact same problem.

Note that the wires in question are white. White, white, white. Or, in the vernacular, WHT.

BLU is nowhere to be seen.

The wires are pre-stripped to expose some shielding. The bared parts of the wires have to be clamped in along with the ignition wires, and have to have their exposed shielded areas in contact with the bigger wires.

The end of that cable gets routed back around the aft end of the engine and down to the area where the wires that come through the firewall are resting. At first glance, I thought I was supposed to feed the connector through the cushioned clamp that holds the main wire bundle. Does that even look possible?

Nope! Luckily, it's not required. What actually happens is that there are two wires that have already been run through the clamp; the ends of those wires have pins that get inserted into a matching connector. These are the other two wires detailed in the note above.  Note the apparent lack of BLU.

I decided that the idea of the wire identifiers ending in '2' being matched together and the wires ending in '3' being put together made perfect sense. I figure I've got better than 50-50 odds of that being right, and if not, it won't be too hard to change to the other configuration.

I then dug out a purple wire that forks at the end. I believe this wire has something to do with some sort of "easy start" functionality. If so, that will be the first easy thing about them.

The difficulty with them is that they have to be inserted in the back end of the A2 and B2 connectors. Do you see the two connectors down under the orange fuel line in the picture below? Those are the A2 and B2 connectors, and the back end of them is the side away from the part you can see in the picture. I remember being offered the opportunity to separate these very connectors a few weeks ago when I first starting working on the engine. The semantics of the directions weren't entirely clear, though, so I did not separate them.

For that, I paid.


Separating the connectors is a delicate operation involving the insertion of the blade of a small screwdriver in exactly the right place and applying exactly the right direction and force to release the locking tab. It's easy once you get the hang of it, but the problem here is that I could not get a screwdriver down below the connectors to use it on the release tab.

There then ensued a good twenty minutes of flailing around trying to find a way to get at those release tabs. I finally came up with the idea of using a screw driver bit from my electric screwdriver collection held tightly in the jaws of a pair of vise grips. It was difficult even with my newly invented tool because I couldn't remember the exact position and pressure required. I eventually gave up trying to figure it out blindly and practiced on the much more accessible A1 connector.

The idea is to insert the purple wires into the unused holes on the connectors. That task is made more difficult (as if it wasn't frustrating enough to even get to this stage) by the presence of a plug placed in each of the holes. The removal of those plugs required the invention of yet another custom tool:

Yep, I just pushed a piece of safety wire down through the top opening of the hole and pushed the plugs out.

All that was left to do was push the purple wires in. Not easy, that. They pins on the wires have to be in exactly the correct rotational position to fit into the connectors. It took a few attempts with the forceps that I picked up in the dental tool aisle at Harbor Freight (Harbor Freight - The Home of Budget Priced Surgical Instruments) to get the pins correctly positioned and pushed into the connectors.

Following that near debacle, it was a relief to next work on a far more accessible piece of wire. This is the wire that runs from the oil pressure sensor back to wherever the aircraft designer needs it to go. Rotax has no idea where that may be, so they give you quite a bit more wire than an RV-12 needs.

I cut off most of that wire and attached what remained to the wires that will connect to the engine management module of the Dynon Skyview, some day.

That was enough for the day, considering that it wasn't nearly as warm in the hangar as I had thought it would be. Here's what it looks like now:

Man, that think is starting to look so much like an airplane that I'm never going to be able to get out of home repair jobs again.

1 comment:

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