LOG of a very mysterious crash

Hello everyone:

Today I flew again my quadcopter after 6 months of getting new parts from another crash (also due to an undetermined cause) in January.

The drone I flew today had new battery, new and better motors, better propellers, higher end ESCs, and also frame (although the frame was the same model than I had installed in January).

The PIXHAWK, GPS and all the electronic devices that came with it were the same, NOT new.

Today I was flying at around 60-70% of the performance capabilities of the drone in terms of speed and mechanical stress when, suddenly and for no apparent reason, It started spining (rolling) and fell to the ground. I couldn't hear any noise or see any part flying in that moment. This crash has triggered all the warnings because I can't really know what the hell happened and neither in the LOG nor the video recording shows the cause (or at least I can't see it).

I'd like some expert to check the LOG/video and try to figure out why it's happening so I can avoid it in the next flight. Thank you so much in advance.

The hard shaking vibrations and strange noise come from the servo that holds the camera which was I little bit broken.

It's a long story, but I could only see the last 4 seconds the crash of January in my FPV Screen and I could see the copter spinning fastly while falling to the ground. Isn't that suspicious? I'm starting to think that my PIXHAWK (common part of equipment used) has some kind of bug or is defective and malfunctioning!

What do you think? Thanks again.

PD: I attached both crashes: RECENT (with new equipment except PIXHAWK) and the OLD one.

Recent_Crash.BIN (479.5 KB)

Old_Crash.BIN (484.4 KB)

It looks like the first time motor 4 went dead. This time motor 2 stop working. current also went down indicating possibly a loose connection. The vibrations on second crash are very high and it may have rattled something loose.

In both cases it looks like mechanical.


Thank you so much! You nailed it! One phase of the motor 2 broke but it wasn’t apparent from the outside. Once I opened the wire I saw the filament had broke from the solder joint so that phase was cut…

I don’t know which values of vibration are considered “ok” and if that higher values I’m getting are significant enough to break a solder joint. Around what values should I be looking for to get when flying? Thanks again!

Typically the flight controller has more of an issue with vibrations then does the copter itself. Mounting the unit on foam is needed to isolate the motor vibrations from the flight controller.

The flight controller records the vibration level so a test flight should show what your normal flight looks like and will tell us if there are serious vibration issues or not.