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Starter will not engage

in General Tech Discussion 11 years ago
Head scratcher this one, at least for me. Recently my 912ULS-equipped aircraft has developed a bizarre problem. First flight of any given day the starter engages and the engine fires normally. Subsequent flights however and the starter simply refuses to engage. Well, not immediately at least. After 5-10 minutes of swearing, panel bashing and button punching, the starter suddenly engages and the engine starts normally. I have a push button starter so immediately suspected it had gone bad, but continuity tests show both it and the lead to the starter relay solenoid are good. What is changing between first start and later unsuccessful attempts, except for the obvious heat buildup. And are solenoids susceptible to heat buildup? And if so why didn't this behavior occur in summer? Any and all ideas welcomed... :pinch:

  • Re: Starter will not engage

    by » 11 years ago

    It could be the solenoid. It does sound like the problem. They seem to work intermittently when you swear at them. LOL
    You can jump across the contacts and see if it works. If it does then it is the solenoid if the key doesn't work. If the starter fails to catch then it is the starter. This may also help rule out the starter switch.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Starter will not engage

    by » 11 years ago

    What's your experience with Rotax starter relays/solenoids Roger? Do they fail often? Are they heat or vibration sensitive? Mine has just over 300 hours on it. And why does it always work when cold, but fails after the first flight? This behavior would seem to rule out the starter unit as defective wouldn't you agree?
      
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  • Re: Starter will not engage

    by » 11 years ago

    I don't think it is the solenoid any more, but the modules. Are you sure it is the starter and not the ignition modules?
    Try this little trick. Run the engine like you would when you fly and try and start it again after you are done like you have described. If it doesn't start that second time don't try and start it again, but instead place an ice bag on top and around the ignition modules for 15-20 minutes. Then try and start it. If it starts right up then it's the ignition modules. Solenoid's are usually quite dependable. They can go bad, but isn't frequent.
    Try the trick above and let us know what happens.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Starter will not engage

    by » 11 years ago

    Hi Mike

    The Modules are nothing to do with the starter motor turning the engine over.

    Can you say which it is. When the engine is warm and you push the starter button, does the engine turn over but not start, or does nothing at all happen.

    If the engine does turn over but doesn't burst into life, then it is probably your modules as Roger has said. If the engine does not turn over, can you hear the clicking of the solenoid if you listen carefully or is there no noise at all.

    If you can't hear anything at all, it could be a poor starter button or solenoid, if you can hear a clicking noise, it could be the cable connecting the solenoid to the starter. They can break down due to vibration, and usually the solenoid is bolted to the bulk head and so there is constant movement which can cause the switched live cable to fail.

    Mark
      
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  • Re: Starter will not engage

    by » 11 years ago

    Thanks for the feedback guys. The problem was that the starter would not turn the engine over, that is, no juice getting to the starter motor. And this on an intermittent basis, as I describe above. Today I checked the integrity of all the cables and found the faston spade connector on the solenoid loose. I tightened the connector with pliers and made two flights. The problem has not reoccurred. Dare I hope this was the solution?
      
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