Tumbling crash 4.0.3 after months of flawless flying. Need log analysis help

500mm quadcopter, just upgraded to from 3.6.x to 4.0.3, Kakute F7, been reliable for months. Loiter, climbing slowing through 80ft, hands off TX, tumbled fluttering to the ground. landed flat in soft ground, mostly minor damage to landing gear, electronics all seems OK. Looking at logs but need some advise. How do I look at the motor behavior? The crash was symptomatic of a motor shutting off or not responding to software. How do I look at everything motor oriented in the logs?

Grab the dataflash log .bin file, upload it somewhere like dropbox and post a link here for us to check out.


Here is a link to a shared folder in a Google drive where you can access the log of the crash. I have had such good success with Arducopter over the year I have been using it, (I switched from inav), that I have had no need to diving in until now. I was very familiar with inav’s BB tools but am staring at a blank wall here! The quad is a home built 500 using DJI motors and a Kakute F7 flight controller. The complete controller stack removes via connectors from a passive motor/esc/battery/gimbal/camera assembly. I am able to change back and forth between an F7 ianv stack and the arducopter stack in less than 5 minutes. I did this to be able to do a direct comparison of identical hardware. Needless to say I never went back to inav. However this does involve the drive signals to the escs running though a 5 pin JR connector which makes me concerned that the crash might be caused by an intermittent ESC signal. However knowing this was a potential point of failure I was careful to check this connector and wiring carefully when building it. I fully intended to hard wire the whole quad but got to enjoy flying it so much I never made the time to do that and it has flown flawlessly of many tens of hours since. I will be eliminating that connector now regardless of the final diagnosis. Thanks for any assistance you can provide.
Ian Turner
Here is the link to a shared folder in my Google drive where I have put the .bin file.

Unfortunately you were not logging RC Out so you can’t look at the command signal to the ESC’s.

How do I set that up for future flights?

Check the box in Mission Planner Standard Parameters for Log Bitmask. You always want this logged.

Thanks I will do that! I am surprised that it is not a default, or did I make a mistake?

The default bitmask value of 176126 will enable RCOUT. But perhaps that’s not the default value for all FC’s. I have a Kakute F7 but don’t recall what the default value is and I would have modified it on initial setup.