Sudden fall from stabilize - log analysis help

Hi guys,

I would like to ask you for help with analyzing log files to find possible cause of my recent crash.


  • Arducopter V3.2 with GPS and PowerModule
  • Minim OSD
  • Flamewheel 450 frame
  • 3S 5000mAh
  • 4x Sunnysky 2212-13
  • 4x 30A HobbyKing F ESC flashed to Simon-K
  • LTomi78 Gymbal with Mobius
  • FrSky Taranis with X8R receiver

Flown for about 50+ flights without any problem. During last flight it suddenly falled from about 15m to the ground. It was in stabilize mode flying about 30km/h in forward direction.

Immediatelly before this flight I had problem with arming Arducopter, it did not react to the arming procedure. After few restarts (by disconnecting main battery and pluging it back) it went back to normal and successfuly arm.

During that flight I saw two restarts of Minim OSD in my googles. For the first time in my life. Approximately 30 seconds after that I lost all thrust and it dropped from the sky like stone, tipping over to its back.

After this accident main battery was still connected and everything was under power (Arducopter, GPS, possition lights). I have radio failsafe configured to RTL function - tested several times by switching off transmitter.

Any help is deeply appreciated. I need to find cause of this to be confident to fly it again.

Best Regards,
Miloslav Stibor
Czech Republic

Here is an Auto Analysis of you data flash log:

Size (kb) 1228.2001953125
No of lines 17169
Duration -1 day, 23:29:06
Vehicletype ArduCopter
Firmware Version V3.2
Firmware Hash c8e0f3e1
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 18.52m
Test: Compass = GOOD - No MAG data, unable to test mag_field interference

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERRs found: FS_BATT GPS_GLITCH GPS
Test: GPS = FAIL - GPS glitch errors found (1)
Min satellites: 0, Max HDop: 1.66
Test: IMU Mismatch = NA -
Test: Parameters = GOOD -
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = WARN - VCC min/max diff 0.332v, should be <0.3v


Thanks for Auto Analysis, I did not know there is such function in Mission Planner. I can see it now. So only “Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 18.52m” seems to be problem. But what does it mean? Did artupilot restart uppon some error? Or there was something wrong with power line of copter? Or something else?

Best Regards,
Miloslav Stibor

It looks like you may have had a brownout that could have caused a restart.

Very low voltage early in the flight. Went right through your FS. The initial voltage drop on takeoff is huge. Time for a new battery.

Yes, there is a huge voltage drop at the beginning of flight. But it is a drop to 10.8 - 11.0 volts under load. Pretty normal voltage fot 3s under load IMHO. Battery FS is stated in graph of voltage but it is switched off and do nothing as consequent action. Drops under FS levels are just momentary under max throtle.

Maybe more interesting is Vcc graph. Should there be so large peaks? Shold it be smoother? Can this be cause of brownout?

I get about half that drop in mine.

The Vcc variation isn’t abnormal, but the value is, it’s oscillating more around 4.7 or so rather than 5, so could be the proximate cause of the brownout.

But why is it so low? Battery is easy to check, or perhaps the BEC that powers your board.

On link bellow Vcc mean value is about 4.5V so I suppose 4.8V is not so low. … sing-logs/

But there is probably problem in my power distribution circuit since Vcc is occasionaly dropping by 0.2V. AMP should be powered by Power Module. I just realised that i have one microservo and one RC switch plugged directly to receiver. So it is on the same positive rail as inputs of AMP and i think it is not recomended. I will separate power for APM totaly from other devices and move them to outputs of AMP wich JS1 jumper removed. I will see if Vcc graph will be more consistent after that.

Anyway, thank you so much for help. It is probably power related issue and I will try to solve that.

Best Regards,
Miloslav Stibor