Copter Not Maintaining Level - Have to recalibrate every reboot

[anbello (Andrea Belloni)]

This seems to me similar to a problem I had described here:

AHRS2\EKF2\EKF3 attitude and altitude estimation

I have a similar problem of difference between the ATTITUDE and AHRS2 messages on a simpler system: a quadcopter without optical flow / lidar. In an indoor test flight in ALT_HOLD the copter, a little bit after take off, keep going back with stick at center (the AHRS_TRIM was adjusted). When I keep the stick at center the ATT msg give near zero pitch, as should be, but the AHR2 msg gives a pitch near 3 deg (growing in time) and the copter drift back. I attach an image and a dataflash log. I …

But I never solved that issue, I changed FC and all went OK, I thought that was a faulted IMU.