APM 2.6 servo lock up. The plane crashed badly. :

http://gsbchkteam.wordpress.com/2014/03/23/first-crash/

The plane was fine in our first flight. But then, in our second flight, our test pilot sudden lost control of the plane and it dropped from the sky.

It is in manual mode.

APM accelerometer data is jumpy now. Here goes $200 USD,

camera, video TX, GPS.... $300 USD...

We were planning to use the plane for our balloon challenge, if it is truly 'coz by APM, please put comment below. Thx. I don't want another crash. 

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  • Moderator

    What we're trying to say is not that there was a servo failure, we don't know that.

    It is possible though. Did you test the servo after the crash?

    The log you posted show the plane did not respond to the electronic output sent to the servos, this we can see.

    So that implies that the control surfaces were probably not moving.

    I don't know why the control surfaces were not moving, it's impossible for the logs to say, that's for you to figure out.

    • Thanks for your help. The plane is total lost. A aileron servo is half stripped but it may 'coz by the fall. 

      Here are the pictures of the plane after crashed

      http://gsbchkteam.wordpress.com/2014/03/23/first-crash/

      And here is the first flight video (Crashed in the second flight)

      http://gsbchkteam.wordpress.com/2014/03/25/first-flight-video/

      • Moderator

        Sorry for your loss, it's terrible when that happens, I too have experienced it more times than I can remember so I know the feeling very well.

        Hope you get up and flying again soon.

        Were you able to check the elevator servo? 

        • Thanks for your reply.

          For the elevator servo, out teammate trim it for gliding.

          I did move one of the aileron servos by hand before the first flight.

          The first flight was fine.

          http://gsbchkteam.wordpress.com/2014/03/25/first-flight-video/

          So, it is no way to check the servo condition until it is broken? Nylon Gear head is not good then.

          If that is the case, I will use metal gear servo for my next plane. 

          • I had the same kind of problem with my setup. I have tried every thing. The plane was flying normal and suddenly it just rolled and went into death spin. I believe there were many factors involved. But the main issue i found was the APM sensitivity towards RF noise. Make sure you don't use a cheap ESC specially if using with BEC. Try to use a ferrite ring on all the wires coming into APM. And make sure your current sensor has a good solid connection with battery and APM.

  • Moderator

    I assume your throttle is on channel 3?

    3701690150?profile=original


    My observations:

    All the channels seem to be working until the crash, ch1(roll) seems to stay level although the plane rolls to 135°, almost upside down.

    Ch2(pitch) goes to 1632 to 2042 and is held there until the crash, is this what your pilot did, hold full elevator until the crash?

    Was he attempting to stop the dive?

    ***The plane was already at 60° down pitch before any elevator was applied, so going pretty fast, GPS says groundspeed was 26m/s, 58mph or 93kmh at that point but that's lower than it's true airspeed because it's diving (airspeed however was stuck at 56 the entire flight).

    Is it possible that at 60° to 83° down pitch and airspeed probably exceeding 70mph/112kmh, the elevator bent or pushrod flexed or the servo wasn't strong enough to stop the dive?

    • Is this the point that one of the aileron servos failed. The plane did not roll back when the channel 1 is low.

      I use Skywalker

      servo_fail.JPG

      https://storage.ning.com/topology/rest/1.0/file/get/3702480188?profile=original
      • Or the plane did not have enough air speed?

        • Moderator

          I would say the servo's or control surfaces were not working properly or not at all after takeoff.

          Your graph plot shows the roll not responding to servo movement (not actual movement but the output to the servo)

          Plot CH2 and pitch and you will see the plane did not respond to elevator servo output either which was fatal.

          • Hmm... so there is no way to check the stripped servo gear until it happens?

            Any good metal gear servo do you recommend? How about EMAX servo?

            Aileron servo failure or Elevator servo failure? 6g servo I guess

            The crash is 'coz by servo failure, not the APM, can I make this conclusion? Thx

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