endotherm
First Officer
Flight distance : 503241 ft
Australia
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I don't think it has anything to do with the battery. These are 15.2V batteries which won't start issuing warnings until about 3.3V per cell. They will need to get down to 3.0V per cell before they shut the battery down to protect it. I agree that there was probably an internal hardware fault that was drawing a lot of power, for example a failing IMU or a dry solder joint. We have previously seen a case of a heavy wire from the main board to the motor cracking, probably due to a crash or hard landing or maybe just fatigue, which caused a similar fall and crash. Even if inspected for maintenance this fault was not likely to be detected as the crack was inside the plastic sheath and not visible. It is possible in this case there was a similar crack and it arced causing high current consumption, eventually leading to a complete separation and failure. If you are not sending it in, I'd be checking these wires first. A disconnected wire would explain why it is the only component not wanting to start up again.
The battery clearly did not shut down, as it was still recording the fall and sending telemetry all the time. We see the capacity rebound once the load is removed. The front two props at least were spinning the whole time during the fall, as seen on the video. One or both of the rear props must have stopped. I suspect the right-rear due to the way it tumbled initially. This can only be checked if the DAT file contained on the aircraft's internal "black box" recorder is extracted and examined, or if a physical examination of the electronics is performed.
For safety most countries forbid flying over people. This is in anticipation of the unexpected happening and it falling on them. It is impossible to develop a maintenance regime that will forsee any disaster, so you need to anticipate S**T HAPPENING and fly accordingly to minimise collateral damage.
All the crazy readings at the end of the log are as a result of the failure, not the cause of it.
Battery voltage per cell:
Battery voltage and remaining capacity:
Temperature vs capacity:
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