Copter 3.2.1 on APM sudden drop in Altitude in Alt-Hold up to a crash

ArduCopter Copter 3.2
1

Hi,

Using APM from CX-20 (open source) version 2.52, encountered few drops in Alt-Hold mode - copter just drops out of the sky, I’ve tried analyzing the logs yet can’t make solid conclusion to what is wrong ?

Any help will be appreciated, logs attached.
2017-05-02 12-13-25.zip (3.0 MB)

2

Your vibration levels will be having a large impact on performance.
Have a look at http://ardupilot.org/copter/docs/common-vibration-damping.html#vibration-damping
I would get those vibrations down a lot and then do an autotune

Screen Shot 2017-05-09 at 5.04.56 am.png2264×1062 767 KB