In flight disarm

Hi All.
I recently asked for help on the DIY drones forum, (of which I have been a member since its inception). Chris sugested I would be more likely to find help here. Can I humbly ask for some help/support regarding my quadcopter disarming in flight?
I am running a Pixracer FC and have been doing so for some time with great reliability however I have recently ben experiencing the dis arm in flight issue. Below is a copy of my post on DIY drones.

I could really use some help, and mentoring, with understanding a flight log!

After many successful flights with my quadcopter I decided to upgrade the power pack (Li-Ion batteries). This entailed moving from 3S, 3P to 4S, 2P. As you would expect I went through the process of re-tuning due to this change!

That’s when my troubles started. During the auto tuning portion of the flight the copter disarmed in flight causing an obvious crash. This is not something I have witnessed with this copter in the past as it’s been super reliable for many flights, including one’s over 3Km, for the past year or so!

This happened a second time in the same circumstances. In these instances I was still running V3.6.9 (632be63f) firmware.

On the 25th June 2020 I had a similar but different issue again the copter disarmed in flight this was a few second after switching into “auto” mode. In this instance I was running V4.0.3 (ffd08628). After a small repair I flew again in only “stabilise”, “alt hold”, and “loiter” modes I flew for over 10 minutes with no issues!

On a subsequent flight this disarming in flight occurred in the “alt hold” mode!

As I said I would appreciate help in understanding the flight log. I have attached the .bin file as a link, to try and resolve this issue.



It is a failsafe event - (16:34:33.800 - 16:34:35.800: difference between DesPitch and Pitch more than 30)
However, no idea about reason because there are no information about motors, throttle and imu in your bin file, you can add it by setting LOG_BITMASK parameter.

Hi Yuri.
Thanks for the response.
I have had very little to do with the Logging up to this point as the quadcopter has been super reliable. I cannot understand this sudden issue as all I have changed is the power pack (battery’s)!
I will adjust the BITMASK as you suggest. However i cannot understand how the PITCH has exceeded the DESIRED PITCH by such a margin as I have been a very cautious flier due to this happening multiple times over the last few weeks!
i appreciate the reply. Thank you.