I have recently crashed my Tarot 650 more than 5+ times with different flight modes at different flight times - always with the same behavior. The quad suddenly rolls left/right (random) and does not stabilize back to level when I let go of the sticks. It sometimes flies with a small 10 degree angle and at other times it does over 30. Only a complete power off-on fixes it, disarm-arm does not.
So the quad decides to fly at various roll angles and sometimes it is so large, no RC input helps to level and land safely. I'm guessing that my accels somehow go nuts, because I have seen my artificial horizon spinning even when the copter is level on the ground.
Today after 3 successful 20+ min flights, I was taking off for a 4th in AttHold and my telemetry was connected to my PC running MP. I gently raised the throttle and it flipped back to the ground. So luckily I have both dataflash and telemetry logs for this less than 30 sec flight. Looking at the ATT - Roll, the quad seems it started rolling even before I even started raising the throttle on the ground. So when I raised the throttle above mid, it immediately tried to counter-correct and landed upside down after ascending tp around 50cm.
Unfortunately my pixhawk is dangereously close to my QBrain 4in1 ESC and 433 mHZ telemetry dongle (all in the center frame) - so this might be an interference problem after all. There's also a FrSky X8 receiver about 15cm away from these three. Other than the sudden roll problem, the quad is perfectly tuned and flies beautifully in all flight modes after tens of hours of PID tuning.
Could anyone analyze the logs and point to the problem? Issue is replicated several times on Copter 3.2.1 and 3.3rc4 firmware. Why would the artificial horizon start making complete circles even on the ground with several minutes of warm-up and perfect GPS HDop?
Many thanks, regards