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Expensive crash on X8 due sudden uncontrolled YAW (Pictures + logs added)

Posted by MR on August 9, 2015 at 1:40pm

There are good days, there are bad days and there are days beyond bad days

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ArduCopter V3.2.1 (36b405fb)

Great day for flying, wind 1-2m/s, sunny. The aircraft was flying great until I started coming back to land. It suddenly started yawing (to the right if I remember correctly), then stopped, then yaw again, stopped and yaw again until it hit a tree. I had no control when it was yawing but I was able to control it when it was not yawing (between the yawing "cycles"). It felt like someone was pushing YAW right stick, it did not feel like it was correcting for a motor/ESC etc error. I would also like to point out that all motors were working when it was in the air. I also included a log if someone is able to point out what caused this not so cheap crash. I was not able to determine the error by looking the log file(s). 

PS. There was a truck crane operator near me with a crane remote if this is relevant in any way. The crane remote should work @ 433Mhz but I am not sure.

logs.rar

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Replies

  • Mark Slater August 15, 2015 at 10:17am

    It seems obvious from the log that there was a mechanical failure on one of the motors.

    • Mark Slater > Mark Slater August 15, 2015 at 10:28am

      RCOU data for output channel 6 shows zero output to channel 6 through the whole flight

      • Mark Slater > Mark Slater August 15, 2015 at 10:35am

        However - there are values in the RAW data for RCOU(6) - might be a MP graph fault.

        • Mark Slater > Mark Slater August 15, 2015 at 10:56am

          Looking further I can see the log file is corrupt - please post the original BIN file.

          • MR > Mark Slater August 15, 2015 at 11:35am

            Thanks for the replies, Mark Slater . Here is the .bin file. 

            195.BIN

  • Romeo Eftemie August 14, 2015 at 2:04am

    Hey MR, this looks suspiciously similar to what happened to my friend's quad.

    Looking at the logs, I see RCIN C4 centered but at the same time under ATT the DesYaw gets the quad spinning.

    The same thing happened in our case, with no control when it was spinning.

    Maybe someone can chime in where is this DesYaw coming from?

  • Moderator
    Gary Mortimer August 9, 2015 at 11:13pm

    Ning won't let me download the .rar maybe zip the logs

  • Andre K. August 9, 2015 at 3:34pm
    If an arm rotated, like in the picture. That would give a result as described, and require lots of skill to fly.
    • MR > Andre K. August 9, 2015 at 10:18pm

      Thanks for the reply, Andre K. Rotated arm will definitely result in uncontrollable YAW behaviour, but it would not "cycle" like it did in my case - it would be continuous. In addition, since I was not far away from the copter, I can safely say, that all arms were straight before the crash.

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