Plane turns upside down 180 degrees

I have X-UAV Talon and Sky Surfer. These two planes flies so well in manual mode. I’ve tried two different modes.While I was flying Talon, I switched to “Autotune” mode, suddenly Talon turned upside down and crashed.
I decided to fly with Sky Surfer without tuning with “Autotune” mode. So first, I flew the Sky Surfer in manual mode and nothing bad happened. On second flight, when I switched to “Auto” mode, it happened again. Plane turned upside down and crashed at the end.
I can upload my data logs and parameter list. Why is this happening?

Its so important to confirm that the feedback direction in the control loops is correct before you take off. Just put it in fly by wire in your hand and check when moving the airframe that the servos respond in the right direction. If its not right and you switch it while flying the plane will try to correct a little left roll with left roll command then as it rolls more left it will add more left roll to correct etc.

Thanks for the reply,
I checked the control surfaces and feedback directions. In stabilize mode, everything works proper. When planes turned upside down twice, they stayed that level. I mean, planes didn’t try to stand straight as if this behaviour is right. What else could it be related to?

Post the .bin logs of the flights. Otherwise we can only guess.

Sage advice from the Wiki (Note FBWA not another flight mode):

Check servo movements

BEFORE EVERY FLIGHT: before take off, hold the aircraft in your hands and switch to FBWA mode, then pitch and tilt the plane it to confirm that the control surfaces move the correct way to return it to level flight. (The ailerons and elevators will move; the rudder only coordinates turns with the ailerons in flight, so it won’t move much on the ground). This will ensure that you haven’t accidentally reversed a channel.

You should do this before every flight, just as you move your control surfaces with your RC transmitter to ensure that nothing’s reversed. Failing to do this is the #1 cause of crashes.

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Hey there, problem was solved. I thought that aileron and roll directions are right but they were not. I confused Pixhawk with another Pixhawk whose servos are right. Thanks for the replies. Have a nice flight!

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