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Thread: forced landing-smoke in the cockpit

  1. #1
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    Default forced landing-smoke in the cockpit

    I had a forced landing today due to smoke in the cockpit. Fortuanetly I was nearby the airport and landed safely after shutting down all the electrical. After removing the foam donuts that my butt cut out of the seat pads, I started troubleshooting. I found that one of the wires from the coils/alternator where it goes into the regulator was fried. Is there a way to test the Ducati regulator? Any ideas on what is going on? I heard a loud squealing in my headset when the smoke got real thick so I wonder if the problem is in the alternator part or in the regulator. Any help is appreciated. Now I am going to have a stiff drink.

    Jerry

    IMG_1658.jpg

    IMG_1660.jpg

    IMG_1661.jpg

  2. #2
    Senior Member Dorsal's Avatar
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    Default Re: forced landing-smoke in the cockpit

    Glad you made it down safely, looks like possibly a problem with the crimp? Do you have signs of extreme heat anywhere else?
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  3. #3
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    Default Re: forced landing-smoke in the cockpit

    That's the weird part, it is only burnt on the end where it plugs in. I know that loose connections will do strange things, but this connection seems tight and clean. It would seem that if the Regulator all of a sudden switched to ground, it would have burned the entire wire not just an inch. After I landed, I turned everything on and it worked. Even ran the engine at idle and the wire didn't burn further. I am tempted to cut off the damaged part, solder a new end on and try again but it took 10 hours in phase one for this problem to surface. I don't want make it a habit of emergency landings!

  4. #4
    Senior Member kmach's Avatar
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    Default Re: forced landing-smoke in the cockpit

    Hi,
    my experience with regulators is , if they burn out it is real noticeable. the back of them melt.

    They don't do anything once burnt and you will not have any charging , but this is just my experience on one regulator.

    From your pictures it looks like a loose connection, though, as you said it seemed tight. I think the same as you, repair the wire, ensure it is connected good , and retry.
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  5. #5
    Senior Member cap01's Avatar
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    Default Re: forced landing-smoke in the cockpit

    jerry , do you have a crowbar installed in the system ?
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  6. #6
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    Default Re: forced landing-smoke in the cockpit

    Not sure what a crow bar is? I am thinking about putting a switch between the "alternator" outputs and the regulator. That way I can turn off the output before the regulator in case I run into this again. I have a Hot box but it hooks in after the regulator. It's strange that there is no fuse or safeguard before the regulator. Maybe that's what the crow bar is? I am a pretty mechanical person and experience is pointing towards a bad connection but...damn, all that smoke was a little spooky especially for a new pilot like me. I would like to do everything possible to make sure I have whatever is wrong fixed before I continue on.

  7. #7
    Senior Member cap01's Avatar
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    Default Re: forced landing-smoke in the cockpit

    a crowbar is a overvoltage protection . a relay is installed in one of the coil leads of the alternator with a c/b controlling it . when the crowbar senses an overvoltage it will short the c/b to ground , causing the relay to open ,effectively turning off the alternator.
    there are a lot of people that arent big fans of the vinyl automotive type terminals and splices . the pidg terminals and splilces are the only way to go ,along with an amp or other high quality crimper .
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  8. #8
    Dave Holl's Avatar
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    Default Re: forced landing-smoke in the cockpit

    It could have also been a high resistance in the crimp rather than a poor spade connection at the regulator.
    Still a scary moment well handled!
    Only other thing worth checking is have you done a total load analysis to ensure you are not drawing to much current normally?
    Dave Holl
    Building Kitfox MK7
    Rotax 912ULS

  9. #9
    Senior Member Dave S's Avatar
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    Default Re: forced landing-smoke in the cockpit

    Jerry,

    I concur with the other members commenting on a possible high resistance connection. Its not burned at the end of the connector and it is not burned further back up the wire.

    I copied the 3rd image and magnified it as best I could - although the resolution isn't real good at that point - it appears that several strands are cut and turned out on the right edge of the burned spot - if that is not an illusion of the photo - the reduced current carrying capacity of the wire connection could account for a hot spot with everything else being normal.

    It can happen where some strands are accidentally cut off or damaged in the stripping process; or, strands cracking off due to vibration; or a crimp that has loosened up, or some of the strands did not get captured within the crimp etc. - any one of which can reduce the current carrying capacity of the wire and cause a local hot spot - as it heats up resistance increases with greater heat developing and the vicious cycle proceeds till enough heat is developed to raise some smoke.

    Sometimes a bum connection can be found before smoking the cabin by frequently checking all connections visually from time to time in the wring-out period.

    If a person carefully picks apart the insulation and connection - I bet you will be able to detect a fault of some kind which may have caused your smoke problem.

    Also goes to show you that keeping your head is what it takes to manage the emergency and avoid any unnecessary problems - just because a person has some smoke doesn't mean you can't handle the aircraft - you dealt with it well.

    FYI - a friend of mine had an electrolytic condenser on an old certified airplane explode under the panel with a loud bang and much smoke on the takeoff run - a quick abort, shutdown and fairly expedient departure from the aircraft followed - although it was an impressive attention getter - the likelyhood of a real fire was pretty remote and never occurred - but you don't know that at the time.

    I bet you will figure this one out soon.

    Sincerely,

    Dave S

  10. #10
    Senior Member Monocock's Avatar
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    Default Re: forced landing-smoke in the cockpit

    Glad it ended safely.
    Kitfox 4 (1050)
    912UL
    Based in UK

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