Wednesday, July 09, 2008

Herding electrons

I paid Papa a rare mid-week visit this afternoon to address a couple of annoying little quirks he's been exhibiting. First, Co-pilot Rick has been complaining that he's not getting any sound through his headsets, and thus can't hear me talking. Now, most people would consider that a feature, but broken is broken and cannot be tolerated.

I went out to the hangar prepared to pull the jacks out of the panel to look for wiring problems or possibly a trapped insect, but decided to approach this particular job in stages. First stage: clean the jacks on the headset. Brasso and elbow grease took a lot of black junk off of them, and now they're putry and shiny. I plugged them in and listened to static on the radio for a few minutes - solid noise. Problem solved? Well, maybe. Maybe not. I really won't know until the next time he flies with me.

The other problem was with the oil pressure gauge. It's been reading low (usually over vast expanses of water or solid-looking trees), but a few taps on the gauge would run it up to red line. Absent the fact that an oil pump is an unbelievably simple piece of machinery (basically it's just two meshed gears spinning and forcing the oil to flow around them) and would not typically fail all at once, one must consider that tapping on the face of the gauge would be very unlikely to even be noticed by the oil pump, much less responded to.

I had a similar problem with the fuel pressure gauge a couple of years ago and ran through a new gauge and transducer before tracing the problem down to a loose ground wire. With that in mind, I have on a couple of occasions reached behind the panel to tighten up the two wires plugged into the back of the gauge. But today was different: I broke out an actual tool! I took an inspection mirror out of the tool box and actually looked at the back of the gauge where, to my surprise, I learned that there are three more wires that I hadn't known about. The two wires I had been securely pressing onto the gauge had nothing to do with the pressure indication at all; they are for the night light. Sigh.

That was good in a way, though, as it still left open the possibility of a zero dollar fix. Two of the wires had red terminals (indication positive polarity, I guessed) and the third was blue. I wiggled the blue terminal and it was tight enough on the spade, but both of the wires pressed into it fell right out. Ok, now that's a clue! I pulled the terminal off and inspection showed that it hadn't been fully crimped. Another tool fixed that, and the terminal was pushed back onto the gauge. Fixed? Don't know. It should be interesting next time I fly!

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