Motor failed in flight during autotune

After making recent changes to my copter (X8) we were attempting to run autotune beginning with a single axis. after about 4-5 minutes the sound abruptly changed so we brought the copter back and as it approached we saw the rear right top motor had stopped.

After landing we powered the vehical on and the motor spooled up … the log is attached. I was hoping someone could have a look for an indication to the problem… esc, motor ect?

I was using new batteries same AH but heavier but different size and weight now displaced toward the rear of the coptor :frowning: Thanks! flight BIN

You can definitely see where Motor 4 lost thrust but it’s often difficult from the log to determine the cause. ESC telemetry can expose more data (RPM) that can help.

Desync possibly because after you disabled Auto Tune it was running again until another of the same event happened.

Hi Dave thanks for having a look…
How do I access ESC telemetry? I an using KDE UAS35 w/ KDE motors… I did contact KDE and they suggested trying to reproduce the issue
So if anyone has a good way to troubleshoot to pinpoint the problem Please let me know. So far I plan to:

  1. flip /rotate the props so they push down then use transmitter to tax the motors to cause failure on #4
  2. I can switch top and Bottom motor esc and rerun test… if bottom motor fails and #4 keeps spinning its most likely the esc
  3. if I cannot reproduce it or if top motor 4 fails after switching esc… then is either motor (is this possible) or wiring (a short?)

How can I check for short on the motor prior to checking esc?


You won’t get ESC telemetry form those ESC’s. The Troubleshooting plans seems sound.


I may have found the issue
We were getting weird messages during autotune… like " cannot level copter" and just now on inspection one of the kde folding props was extremely loose… so I lifted up on it to find only the screw was holding the prop…there was an incredible amount of vertical play… amazed it didnt come off in flight

Hoping this is the cause


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