Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater
"Anyone know anything about magnetos?"
After my comparatively failed trip to Arlington on Thursday evening, I decided to try again today. I got a late start (I needed the sleep) and was up there by about noon.
I tooled around the ultralight hangars again, but this time actually spotted a few people moving around. I pulled up in front of the largest group (all two of them), and doffed my disturbingly warm riding clothes (it was at least 90° F out there today).
I started up a brief conversation, and it turned out that the talkative guy was the owner of "Let's go flying!" which is an ultralight instruction firm (or something like that). "Demo flights are $65, and I charge $140 an hour. Not that I'm trying to pressure you or anything." He seemed like a fine guy, and I didn't feel pressured. He introduced me to the two people who were over by his ultralight: Idaho Joe, and Elmer. "Elmer just finished building that plane over there!" he said, waving in the general direction of half a dozen planes in hangars.
It turned out that Elmer had come over for a reason. "Anyone know anything about magnetos?" he asked. "I know some, although I'm hardly an expert on them," I volunteered. The talkative guy (whose name I've thoroughly forgotten, of course) burst out cheerfully, "that's what we like to hear! You're going to be very popular around here, Ian!" (he had, of course, already memorized my name).
I followed Elmer over to the newly finished plane ("it hasn't even flown yet," reported Elmer), and he described the engine running on the left magneto but not on the right.
Quick diversion for the non-geeks among my 3 readers: a magneto is this clever thing which produces a spark for an engine without the assistance of a battery. Almost all airplanes have two of them, so that if one conks out, your engine is still running. Airplanes are all about redundancy where possible. Anyway, most airplanes have two magnetos, and a switch up in the cockpit to switch between the left, the right and both magnetos running the engine.
Back to our story. Under a bit of questioning, Elmer further reported that the right mag used to work, but it didn't work this morning, and he didn't know what to do about it. After about 5 minutes talking with him, it was clear that he had followed the instructions in the kit without really knowing what he was hooking up, when running all the wires in the plane. That's fine, but it makes troubleshooting a real chore.
Fortunately, I was able to give him a bit of impromptu instruction in how most magneto systems work. Then I got back to the engine (the plane uses a pusher prop, where the propeller and engine are mounted behind the wing), and saw that there were no magnetos. Of course. This engine (a Rotax 503 if that means anything to you) uses the more modern electronic ignition which the non-aviation parts of the world standardized on 30 years ago. That complicated things a bit, but we eventually worked through it.
First thing was to test the mag switch (think of it as being like an ignition switch in a car -- same function, different design). He operated the switch while I poked and prodded with the multimeter I usually have in my bag (have I mentioned recently that I'm a total geek?). Something wasn't right, but I attributed it to my lack of detailed knowledge on this particular engine setup.
We moved back to the engine, where I saw a host of wire connections buried beneath a wad of black electrician's tape. Normally, a wad of black electrician's tape is home to a horrifying electron graveyard of terrible wire connections, but Elmer's work there had been effective if a touch basic. No problems there. I was starting to feel stumped.
We moved back up to the mag switch (side note: a lovely thing about ultralights and similar airplanes: there's very little digging to be done to get to all these connections -- Elmer just pulled a piece of fabric off its velcro and we had full access -- a normal airplane would have required extreme contortions to get to these contacts, and I would have required a 4 year degree to legally do what I was doing). We ran through the testing sequence again, but this time something was different. One terminal which had been unresponsive last time was now changing. Only, it wasn't changing the way it should have. Hmm.
"Elmer, try wiggling the key back and forth, just jiggle it," I said. Sure enough, the multimeter beeped in time with the key's gyrations. *sigh* "That's it," I said. "The switch is bad." Lame. Lame.
One of the weird and/or annoying things about this situation is that the switch was basically brand new. He estimated he'd cycled it from OFF to START and back maybe 10 times. This is a part which appeared to be a certified switch (I actually don't know now if mag switches can be certified or not), which costs on the order of $90 to replace. I just hope he can get a replacement without having to spend the $90 to get it.
The other annoying thing is that this plane (according to Elmer) was at that moment ready to fly for the first time, except for that dratted switch. The kit manufacturer (who provided the switch with the kit) is in Florida, and doubtless was unreachable by the time we found the problem (around 1 pm Pacific, or 4 pm Eastern). Looks like Elmer's grounded for a little while longer.
Eventually, after profuse thanks for helping him out, I left Elmer to his own devices and headed out to eat a very delayed breakfast. This time, the Taildragger Cafe was open, and it was every bit as pleasant as it had appeared through the locked door on Thursday evening.
Posted at 18:25 permanent link category: /aviation
Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater