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Thread: Ignition Module Wires, Repair Advice

  1. #1
    RF47's Avatar
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    Default Ignition Module Wires, Repair Advice

    Hi, I have a 912 ULS with ~190 hrs (on a Kitfox IV on straight floats). Very close to the harness's plug for the ignition modules I found some bad wires, one that was broken under the coating, and a few others near breaking. The wires from the ignition modules are short to start with, not leaving much to work with. I have been going back and forth regarding the best way to fix this and am debating between the following choices;

    1) Shortening all the wires to remove the portion closest to the plug and crimping on new terminals. This will remove the portion of the wires that were work-hardened during vibration of the connector, but result in a very short harness (which should be fine).

    2) Cut all wires near the module, then use shrink wrap butt connectors to secure new longer wires (with terminals, and plugs). This should be secure, although 12 butt connectors so close together may make for a large bundle that will be vibration prone.

    3) Cut all wires near the module, then solder on and very well secure new wires (with terminals, and plugs). I am not a big fan of this, as the solder joint could be a common point of failure in the future unless very well secured. I generally try to avoid soldering for aviation work.

    4) Order new Rotax (Ducati) ignition modules. This is the least desirable option as the modules I have work just fine other than the poor wiring. The modules are not inexpensive to say the least.

    5) Order new aftermarket ignition modules. I found an individual (Allistair Wilson) that sells new modules with the soft-start built in for ~$250 each. I have no idea if these are good quality and safe, although I did speak with him and he was very knowledgeable and helpful. But again, $500 for new modules vs ~$25 for new wire and connectors to fix my existing modules is a big difference if the outcome and safety is the same.

    A last note on this, at the same time I will be moving the modules and coils to the solid portion of the engine mount to reduce vibration on them. This however has its own drawbacks, as now the wires from the trigger to the modules, along with the spark plug wires, must flex as the engine moves relative to the frame. Despite that, this is likely the way I will go to reduce vibration of the modules and coils themselves.

    I know this is a fairly common problem, but I can't locate specific direction on solutions. If you could please lend your advice for items 1-5 above, or offer an alternative solution it would be great! Thanks in advance for the guidance with this, much appreciated!! Rick

  2. #2

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    Default Re: Ignition Module Wires, Repair Advice

    #3 solder.

    Butt connectors have no place in an airplane.

  3. #3
    RF47's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Thanks for the quick reply 4Hummer. I think you are right, a solid lineman's splice with minimal solder, coupled with good fixation of the wires to avoid movement should be plenty strong. Thanks! Anyone else care to chime in, or have experience fixing this?

  4. #4
    Senior Member 109JB's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)

  5. #5
    Senior Member jrevens's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Quote Originally Posted by 4Hummer View Post
    #3 solder.

    Butt connectors have no place in an airplane.
    While I'm not a particular fan of butt connectors in general, there is absolutely nothing wrong with using properly sized, good quality ones (AMP, T&B, etc.) on an airplane, IMHO. It's best to use the ones that crimp & hold the wire insulation as well as the wire, for strain relief and support. They need to be installed with the proper tool. This type of electrical connection is used on a large percentage of factory-built as well as homebuilt aircraft, of all kinds, for wire terminal ends, Faston connectors, butt/splice connectors, etc.

    I do personally like soldered connections, well-made, and using adhesive-lined heat shrink tubing to seal and stiffen the joint for a small distance, to prevent flexing at the solder-stiffened wire joint.

    The key with the Rotax ignition modules is to keep the wires that exit the modules from flexing/moving in relation to the modules for a distance before allowing a small, reasonable amount of flexing as necessary.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE

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    RF47's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?

  7. #7
    Senior Member 109JB's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Quote Originally Posted by RF47 View Post
    Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?
    According to the specs, it takes 280 deg F to melt the solder. I would not be worried.
    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)

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    Default Re: Ignition Module Wires, Repair Advice

    I bought one of those modules from Allistare Wilson. I tried it on the 912 UL, and it worked fine. Ended up not needing it and so it's in a drawer waiting till I install the ULS and I will use it on that engine cause it has a soft start module built into it. I would not hesitated to get another one if needed. I also moved my modules to the firewall side of the motor mount to avoid broken wires in the future. If I was you, I would maybe fix both modules you have, install one of the aftermarket ones, and have a spare Rotax one if you ever need it. JImChuk

  9. #9
    Senior Member jrevens's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Quote Originally Posted by RF47 View Post
    Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?
    Not at all silly… as John B. said, it shouldn’t be a problem. However, “solder sleeves” have gotten mixed reviews from people. Bob Nuckolls was (is?) a fan, but then noted some problems with them…. incomplete or poor flow of the solder into the wire for one thing, I believe. I think variable quality may be an issue, like with so many things made in China especially. That’s just my personal opinion and experience.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE

  10. #10
    Senior Member Rodney's Avatar
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    Default Re: Ignition Module Wires, Repair Advice

    Just put on a new set of modules from Alistair Wilson. They are really well made and he was a pleasure to deal with.

    My engine just would not run on the "A" side of the ignition. I traced everything I could; You have to understand I'm very limited
    when it comes to electronics.

    What I eventually found really surprised me. I had four bad spark plugs - all on the A side. I've never had that happen before.
    I replaced all the NGK spark plugs with Champions and my engine is running fine. The reason I went with Champions is that I live in
    a small community and that was all I could get. Even had to go to two parts stores to get a collection of 8 plugs.

    Still - I like the modules I got from Alistair - very easy to install and I moved them away from being on top of the engine.

    Regards
    Rodney

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