13th August 2012

Ignition testing

Hours: 1.3 | Posted in Flight Test

More work trying to track down the engine trouble tonight.

  • Verified the timing on both ignitions was a) correct and b) synced to the other ignition.
  • Connected the Emag EICAD monitor software and verified that the position indicators read correctly and matched, and that the settings for advance, etc were correct.
  • Checked that the overtemp sticker on both ignitions had not tripped.

Everything seemed to check out OK, so I rolled the plane out to run the engine.  I tried all the various combinations of ignitions on and off, ship power on and off, and so on.  I never detected a stumble, and the data logs don’t indicate anything out of the ordinary either.  There’s none of the EGT drops we saw in the logs from Saturday.

So where does that leave me…feeling unsatisfied.  I dislike intermittent problems that resolve themselves with no “smoking gun” to show why they happened.  Granted, I don’t know that this has actually resolved, since it was never seen in any of the earlier ground runs and only happened after flight.  Over the course of tonight’s 3 runups and some taxi time, the CHT’s reached the upper 200′s, but that’s far from the hard, hot running in flight.

We did touch a bunch of things in the troubleshooting process — essentially every connection and wire in the ignition system, some spark plugs, fuel injectors — so if there was something loose or intermittent there, it could have been fixed.  However, I guess I’m expecting the stumble to reoccur after the next flight, at which point we’ll be back to square one.

While I had the RS-232 adapter out, I also reprogrammed the APRS transmitter to shut off the telemetry channels, since there’s nothing connected to them.

Also verified that the AWOS is still scratchy and only occasionally breaks squelch while taxiing around the field.

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