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Lane Check results in severe shuddering when Lane A switched off. EGT for cylinders 1 & 2 then drops over 400 C. Coil 2 failed the resistance check and was replaced but problem remained. Sparks at plugs 1T & 2T were very weak. Oscilloscope traces for all four coils show 420 volts on 1, 3, & 4, but only 120 volts on the lead to coil 2. The ECU was sent to Floods and they only suggested clips be put on the airbox sensors, which we did, but the ignition problem remains. Rockwell Collins were asked for advice but they replied that the responsible division had been disbanded. We suspect the driver transistor for that coil has residual current when it should be cut off, but this is only a guess as the ECU is not a user-servicable part. A replacement ECU is NZ$15,000 (seriously). A local company would attempt a repair if we had an ECU internals circuit diagram(!). Any suggestions, please, as without redundancy we can only do circuits(!)?
  • Re: Lane B ignition fails two cylinders

    by » one year ago


    such service problems are going to cripple sales of this engine if they continue. I think i might have bought a lemon.

  • Re: Lane B ignition fails two cylinders

    by » one year ago


    Most of the issues that have anything to do with wiring has been mostly caused by aircraft MFG's or owners not following the Rotax wiring. It is specific, but many figure they can do it a different way. They are finding out that isn't true.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Lane B ignition fails two cylinders

    by » one year ago


    Yes, there are various ways to subvert the ROTAX intention. However, in this case the wiring between fuse box, coils, switches, lights and ECU is completely and only the original harness supplied with the engine, which has now run 600 trouble-free hours until it suddenly failed the Lane Test prior to a flight, and was immediately grounded pending repair.
    Peter

  • Re: Lane B ignition fails two cylinders

    by » one year ago


    You can look for wires rubbed through. I have seen two of those where the wires became abraded.
    It's just being through in your diagnosis.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Lane B ignition fails two cylinders

    by » one year ago


    Good point - however the particular conductor tests fine for both continuity and meg to 500v, and in use copes with 120v (though it should reach 420v). Also, it is encased in the ROTAX-supplied wiring harness, which is tightly wrapped in adhesive fabric and contains maybe 100 conductors. But we have flexed it within that wrapping, throughout the affected lengths and have not changed the behaviour. It's probably most unlikely - but difficult to prove, either way. It's odd, though, for something like a chafing fault to show up, suddenly, in so well protected a harness.
    But we won't rule it out.
    Thanks, Peter

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