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I'm at 1,600 hours on my 912iS and have now had two failed ignition coils within the last few months.  They were easy to diagnose although it's worth noting that it will not necessarily throw a lane light/fault code.

They were both identified during the runup. Shutting down Lane A at 4,000 rpms produced a very rough running engine and a significant drop in EGT on Cylinder #3.  Having just installed a new fuel injector on 3T, we concluded it had to be the ignition coil.  

Coil #4 replaced.  Problem solved.

I'm going to start traveling with a spare coil and a set of metric allen wrenchs in my flight bag as I still have two of the old coils on the engine.


Aviation Real Estate Specialist & iRMT

  • Re: Lifespan of a Double Ignition Coil

    by » 3 weeks ago


    Hi Jim,

    Unfortunately, the ignition coils currently installed on your engine (P/N 665 613) will soon no longer be available for purchase. Rotax is transitioning to a standardized ignition coil design that uses a single sealed Tyco connector, replacing the older version that uses two Faston connectors. The new Tyco-style coils are designed to be more robust and reliable than the older Faston-type coils.

    Engines with serial numbers 10002783 and higher are already equipped with this updated ignition coil configuration.

     

    • Old Ignition Coil: P/N 665 613
    • New Ignition Coils: P/N 864660 (61, 62, and 63)

     

    This change means that if even one of your existing coils (P/N 665 613) fails, you will need to replace all ignition coils, the entire wiring harness, and the ignition leads at the same time. There is no adapter available to connect the new coils to the old-style wiring harness, and mixing the old and new coil types is not possible. 

    As of now, Rotax has not provided a timeline for how long the old-style coils will remain available. For more information, please check out the video we released on this topic and refer to the attached Service Instruction issued in February 2024.

     

    Introduction of new double ignition coils and new wiring harnesses for ROTAX® Engine Type 912 i (Series), 915 i (Series) and 916 i (Series)

    https://www.rotax-owner.com/en/videos-topmenu/912-is-videos/768

     

     

     

    42857_2_SI-912 i-029_915 i-012_916 i-007_Introduction of new double ignition coils and new wiring harnesses for ROTAX Engine Type 912 i Series 915 i Series and 916 i Series.pdf (You do not have access to download this file.)

  • Re: Lifespan of a Double Ignition Coil

    by » 3 weeks ago


    From the doc, it looks like the wiring harness for the coils, and the rest of the electrics, are two separate pieces. Can one replace the harness just for the coils, or does the entire bowl of spaghetti, all the way back to the ECU, have to be replaced to use the new coils?

     

    42858_2_Screenshot 2025-06-05 at 11.18.26AM.png (You do not have access to download this file.)

  • Re: Lifespan of a Double Ignition Coil

    by » 3 weeks ago


    Hi Jason

    Good question but the answer from Rotax is not what one will like.  The coil with the new connectors will require the harness be replaced.  The electrical people has said that splicing into the harness is not something they can recommend.  Apparently it will disrupt the signal to the ECU.  The issue with the blade type connector is the vibration causes the push on part,, on the harness, to become loose after a period of time.  This varies with aircraft OEM and porp combinations.  Before you replace the coil try to tighten the blade push on side and be sure to have some dielectric grease on the connection.  

    I am pretty sure that they have a lot of stock of the old version at the moment.  As they swing into the new style they will still be carried for a while in stock.  

    Cheers


  • Re: Lifespan of a Double Ignition Coil

    by » 3 weeks ago


    Jason,

    What you are seeing in the diagram is a single wiring harness.  What looks like a separate harness for the coils is actually the spark plug wires shown attached to the coils.  


  • Re: Lifespan of a Double Ignition Coil

    by » 3 weeks ago


    Rotax-Owner

    The SI introduces the new coils and wiring harness but makes no mention of discontinuing the old style coil.  Do you have knowledge this will happen or are you going by similar instances in the past? The wiring harness is $2700, and each coil is about $400.00, so with tax you are close to $5k in parts alone.  It would be a bad day to lose a single ignition coil and have to spend this much money in parts and a days labor to install. This is the kind of thing that really puts people off.  


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