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  • Trex 500 scare

    Hi all,
    Today at the field I was happily flying about with my Trex 500 when it suddenly began to piro every 1 to 2 secs. It seemed to piro round relatively quickly then hold then piro round again.
    Needless to say I had quite a job fighting with it to get it relatively close and around 10 ft off the ground before hitting the hold switch and dropping it into (thankfully) long grass.
    When I got to the heli I found that the tail servo (an S9254) was jittering around and the 401 gyro light flashing indicating rudder input.
    Thankfully there was no damage to the heli as it landed the right way up.
    After pulling the battery and getting back to the bench I plugged the battery back in and all seemed to be well again?
    Obviously I didn't take the bird back up again.
    When I got home I reprogrammed the ESC to output 5V as it was set to 5.5V as I had heard that the 9254 doesn't like high voltage.
    I also noticed that there was a little bit of rudder trim and I began to wonder if this might have been the cause of the problem.

    I say this because when I power on the heli I always have the transmitter set to 'hold' as a safegaurd against the motor spinning up. When set to hold I power up the heli and the 401 shows a steady light indicating that it is in HH mode and that there is no external rudder input.
    When I set the hold switch to 'off' however the 401 begins to blink indicating that there is some rudder input (which is true since there is a small amount of trim). I have since dialled out the rudder trim and the 401 behaves as expected.

    I have also since added the anti-static grounding mod to the tail boom in case this was the cause of the problem.

    My problem is that I have now lost confidence in the setup and am worried that the problem may re-occur since I can't be sure what caused it in the first place.
    All of the kit is practically new having only flown around 6 times so far.

    Anyone got any ideas?
    Sorry for the long post.
    Adrian.
    sigpic
    http://www.passrightmotoringschool.co.uk

  • #2
    Try and push and pull the 9254 servo arm against its power and see if it gives up and moves easily sometimes.
    On a 50 size a failing 9254 gives an occasional 90 degree tail step out. Maybe a full piro sometimes? or its worse on a 500?
    over 5v might have shortened its life.

    There was a recent thread tha talked about failing 9254s.
    www.heli-extreme.co.uk a good club in south Sheffield
    600n pro BeastX Align DFC head bls251, 3xbls451, align gov, 600d, 2in1
    trex500, BeastX DS510 swash, Beast X cutr and carve head DS520 HK3026-1900, Align 425D blades, 5S4200 rev'trix, K&BDD dampers, AR6200
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    Dont spend more flying models than it costs to fly for real

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    • #3
      Originally posted by moyesboy View Post
      Try and push and pull the 9254 servo arm against its power and see if it gives up and moves easily sometimes.
      On a 50 size a failing 9254 gives an occasional 90 degree tail step out. Maybe a full piro sometimes? or its worse on a 500?
      over 5v might have shortened its life.

      There was a recent thread tha talked about failing 9254s.
      Cheers,
      Already tried that and the servo functions perfectly i.e I can't force it out of lock. It holds the tail very well.
      got a link to the failing 9254 thread?
      Adrian.
      sigpic
      http://www.passrightmotoringschool.co.uk

      Comment


      • #4
        the light flashing on a 401 means it was not in HH mode when switched on or you were moving the heli while booting....OR...you just got your first static hit and your gyro has reset which sounds likely to me.

        i'm afraid you won't find "A" thread on failing 9254's...you will find thousands on different forums. i have lost a few myself so i don't use them anymore. that said it sounds like you possibly had a reboot in flight with this one or your servo is on way as it was jittering. hard to say without seeing it. looks like you have some pointers on where to look anyway.

        cheers

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        • #5
          Hi Adrian sounds like a static hit

          earth the motor mount and frames and boom all to the neg side of the ESC and try it again m8y, check you got a good earth with a multi meter

          Jason
          DMHC = Nice place to fly!
          MyPhotoBucket


          mmm what shall I buy next

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          • #6
            Hi,
            I have since done the earth mod and so far so good.
            I also reduced the output voltage on the BEC from 5.5V to 5V.
            Had 4 succesful flights yesterday with a couple of inverted holds.
            Things just seem to be getting better and better with my confidence growing with each succesful flight.
            Hopefully, I won't get too cocky and ditch it just yet.
            Ade.
            sigpic
            http://www.passrightmotoringschool.co.uk

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            • #7
              Your doing well Ade,

              Keep up the good flying. When you down next?

              Cheers
              Cheers Matt

              sigpic

              www.flpflightteam.co.uk/ http://www.simstick.co.uk/

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              • #8
                Originally posted by mattie-lodge View Post
                Your doing well Ade,

                Keep up the good flying. When you down next?

                Cheers
                Thanks for the vote of confidence Mat.
                Don't know if I will be able to make it down this week though.
                Dad is with me until the 31st after that the sky is the limit. (Pun intended!)
                Ade.
                sigpic
                http://www.passrightmotoringschool.co.uk

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