I had a first serious crash with Pixhawk (3.1.3 firmware) yesterday. The copter has been flying very nice so far (around 200 minutes), very stable, Loiter was superb, there were just minor problems with AltHold.
It armed OK yesterday, but after 20 seconds it just fell from few meters. It was in stabilize mode at that time. No special maneuvers were going on, it just looked as brownout to me.
Pixhawk was powered by HK 5A BEC and motors by Attopilot 180 module. There were no problems with it so far.
What is for sure is that it was not the LiPo issue, I was able to take off and fly for another 10 minutes with the same battery. Copter behaved just normally at the 2nd attempt.
There was not that much of damage, landing gear was just slightly damaged, but everything is already fixed today.
I have spent some time analyzing the log files, but without any outcome. I would really appreciate if someone more experienced can have a look at the log files, I am just scared to go out flying again until I get the idea about what was going wrong.
I’m not expert, my opinion:
Your VCC is between 4.940 and 5.020. You said you’re powering Pixhawk with HK BEC.
Well. in your tlog, after takeoff and before the crash, the telemetry TX did not provide data to you PC, and your quad had flown and crash at few meters. Telemetry antenna problem ?
I think your problem could be powering BEC, that for some reason was not able to properly feed Pixhawk and its sensors and accessories.
I use 3DR power module, and all my VCC_logs, with GPS and Telemetry TX is ever between 5.100 volt and 5.180 volt
thank you for your answer and time… I am thinking about BEC/brownout as most probable reason for the crash as well. The BEC I am using is rated at 5A and there is just a standard stuff powered from pixhawk: 3DR GPS, X8R RX and the MinimOSD (both sides).
I checked few of my old logs and VCC was always a bit bellow 5V, it was just the first time that pixhawk stopped working.
I would consider PM for powering the pixhawk, but I am running the 6S setup.
I am going to change BEC and I would appreciate any suggestions for good ones…
You are right about antenna problem, I have some problems with reception when antenna is close to the ground.
about the antenna that is my guess that you have not had more signal because the pixhawk maybe might had powering problems, this could be reason the signal has gone away moments before the crash.