I have funny vibration on loiter, althold and Rtl. Probably pid issues. Does anyone know how to tune it? TREX 450

Hi everyone, i have managed to install a pixhawk to my Trex 400 electric helicopter. It flies perfectly stable on stabilize mode however when i switch to rtl, althold or loiter it starts to vibrate in a funny way however it still flies. It can return to land by itself and hold some kind of position while vibrating in a weird way. Here is the video of the flights and behaviours that i described here. https://youtu.be/3Dt4FO4C8L0 if anyone experienced a similar situation it would be great if you can help. The p value is at 0.080 it cant go lower (unless i modify it from param list) should i lower it till it flies better? Thank you! I also attached my param files heli450param.param (10.9 KB)

Have a look at this thread

Swash plate setup changing by itself Trad heli using F/W 3.4.6

Your ACCEL_Z_P,0.5 param setting is for multicopters. Change it to 0.3

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This is definitely tuning issue. We will be able to tell more if you post a log. Please change your param LOG_BITMASK from 176126 to 180221. This will enable the PID to be logged as well. This helps in analysis. Also please change the value of ACCEL_Z_P as suggested by Steve_Mitchell. Also do not fly your heli for too long when this happens, quickly change to Stabilize. This can destroy your heli.

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ACCEL_Z_P fixed nearly all my problems, Loiter althold and rtl was quite smooth after it. From time to time I have oscillations but If I land and stabilize the copter on the ground it disappears. I will post my logs after I replace my motor, sadly burnt it today… Thanks for the advice.