A day well wasted

I took the Lance over to Batavia for service. It was only supposed to take a couple of hours, and I’d be back at work before 11:00. Of course, it didn’t work out that way.

The service was to look at one theory about this problem we’ve been having with the Lance this year, where three times so far when the plane has been being used for training (specifically, slow flight and stall recovery, followed by some touch and goes), on rollout after the flight the engine has stopped dead on the taxiway and been impossible to restart. The last time this happened, last week, it was at Batavia and the mechanics pulled the plugs and found them clean and dry, so it wasn’t fouled plugs or flooding. I had had it suggested to me on Usenet that the problem was the fuel pressure was too low, and since the fuel pressure guage in the plane vibrates terribly it seemed plausible to me, so I have taking it out to have this checked.

The first hurdle, however, was getting it started. What the person who had the problems last week told me was that as well as dying in Batavia, after they’d pulled the plugs and put them back, they’d started up, flown home and then it had died again on the taxiway in Rochester. What he hadn’t told me was that he’d killed the battery attempting to restart it in Rochester. As well as finding the battery dead, the avionics master was still on and the transponder was still set to Mode C, all signs that he hadn’t done a proper shut-down. So for about the sixth time in the last 8 months, I had to take off the side access panel and recharge the battery. That wasted nearly an hour, but afterwards it started as easily as it normally does when it’s cold.

After I got to Batavia, the mechanic (who knows me by name, damn I wish I remembered his name) hooked up his little magic box with some gauges. It took him a long time, because none of the fittings fitted the way they were meant to. But he got it fitted up, we started up and taxied over to a runup-pad, and while the gauge hardly read anything, at full throttle it would come a bit off the peg. That’s when he realized his mistake – he’d hooked it up to where the fuel flow gauge goes, not the fuel pressure gauge. That’s probably why none of the fittings fit.

Then he hooked it up to the proper location, and verified that the fuel pressure in all regimes of throttle and mixture was a nice healthy 22 psi (and 23 psi with the electric fuel pump on).

So at this point, it’s past 11am, and we’re all baffled. The mechanic suggests I bring the plane back some time when I can leave it for a few days, so I say I’ll arrange for transport and bring it back later this week. We button up the plane, I successfully employ his hot-starting technique, and off I go.

Or at least I go to the end of the runway, where I perform my normal run-up, and for the first time in my flying career, the engine fails the mag check. It’s perfectly happy on both mags, it’s perfectly happy on the right mags, but on the left mags the RPMs drop to nearly nothing and I have to switch back to both before the engine quits. I try running at high revs and leaned out so far the RPMS are dropping, I try running on the right mags and then switching to the left, and nothing can clear the problem. So I head back to the shop.

The mechanic says he wants to try, and so he starts the engine with his hot starting technique (which barely works) and he taxis over to a runup pad and does some messing around which produces some impressive clouds of black smoke and backfires, but as he taxis back to the shop it dies again and he can’t restart it.

At this point I decide to find another way home, and to leave the Lance there until they can figure out what the problem is. Well, short of the fact that it has 2600 hours on the engine and the last annual showed some slight drops in the compression for the first time in 20 years. Yeah, we probably shouldn’t fly the plane until we either put a new engine in it or sell it, but I don’t think either of those is going to happen soon. I hoping we can find a quicker and cheaper solution.

One thought on “A day well wasted”

  1. During the runup of my second flight with a passenger (my mom) one of the mags failed the test. Fortunately, it re-started just fine after I ran through the checklists and made sure that everything else was as it should be. The replacement plane passed the tests and I’m happy to report that the flight was otherwise uneventful.

    Why isn’t there a greater difference in the fuel pressure between when the fuel pump is turned off and when it’s turned on?

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