8 inch quadcopter tilt suddenly only while landing but forward flying and hovering all OK tunned several time without success can it be a motor issues while forward fast flying is very good.
Motor Emax Eco III 1500KV 2807 tested also with 7 inch propellers also same behaviour.
ESC iflight blitz 80A
FC blitz H7.
Frame Apex HD 8 inch.
Vertical acceleration controller gains look high for the hover thrust. Then try setting PSC_JERK_Z back to default and see if it helps.
I think it’s default PSC_JERK_Z =10
That’s not what I see:
I’m not suggesting that you can’t raise this jerk parameter, just rule it out during troubleshooting.
I think PSC_ACCZ_P and PSC_ACCZ_I values are incorrect looking at MOT_THST_HOVER. Also seems MOT_SPIN_MIN seems almost same as MOT_THST_HOVER.
Second thing - vibration levels are on a high side (I would say on the edge of OK values), and that connected with propwash on descending might be source of some instability.
BTW - what is You thrust to weight ratio? Hoover thrust learning is not going below 0.125 and You might need to set this manually.
OK I will set it to default 
What about this parameter MOT_SLEW_DN_TIME should I adjust it up..?
I have never used other than default (no limit) for those parameters.
But motors is not suspected as for fast forward flying is smooth and also takeoff without any issue only when come to land correct.
Have you addressed what we have suggested?
Waiting for less wind then test. Wind speed 28kmh
You may lower your amount of filtering, it will reduce the delay and will allow to set higher PIDs which helpful in case of propwash, also review your vertical acceleration controller as mentioned before.
For filtering try something like this, it will push LPF higher and reduce amount for dynamic notch filtering, 3rd harmonic not really necessary.
Can you tell me how you loaded log file in MP that parameters are shown?
I get all parameters from log file with ardupilot Web tool or UAV log viewer.
The AMC software ships the extract_param_defaults.py script that extracts both parameters and parameter default values from a .bin dataflash log file
These are the changed parameters while we are in 7 inch propellers
MOT_THST_EXPO 0.62
MOT_THST_HOVER 0.132
PSC_JERK_Z 5
The fall down behaviour while landing disappears successfully but we when we swapped back to 8 inch we can’t test due to high oscillation on hover as shown here in the video https://youtube.com/shorts/q0qQp8w2msc?si=gJZoQTnqVkPpDFby
not sure why tuning with different props, but… after MOT_THST_HOVER learned You need to setup PSC_ACCZ_P and PSC_ACCZ_I accordingly, as described here: Initial Tuning Flight — Copter documentation
What concerns oscillations - decrease PID values if that is the source of it. That also looks a bit similar to how my small 3d printed drone behaved due to excessive vibrations level.
As we have told you set the vertical acceleration controller gains properly based on hover thrust.
