Fly problem but no anything was modified

Hi friends,
i have a problem whit my exa tarot690 13’ prop.
In my last fly i’m see perturbations in Loiter mode but also in Althold.
My Arducopter version is always the same 4.0.3. My PID is the same. My payload the same.
Do you have an explanation for this problem?
I attach my log.
26-06-2020 Fly OK
05-11-2020 Fly PROBLEM
Thank’s to all for HELP.
@dkemxr @smartdave @xfacta

Hi @Sicildroni
the only problem i can see is poor tune of this copter

did you completed tuning process instruction ?

Hi @hosein_gh thanks for your reply.
Yes i completed tuning and in first log you see good curves match but in the second log the match is deteriorated.
The valors of PID is the same in the two logs but inexyplicable the behaviour is totally different.
Do you have an answer for this?

Your Rate Pitch and Roll filters (FLTD/FLTT) may be too low for a 13" craft. You may want to change them to 15-17 and run another Autotune. Ot jus see how it flies with only those changes.

Hi @dkemxr thanks for your reply.
I will apply your advices but my question remain. In previous flights everything is ok and then, without changing anything, the tuning while remaining identical is no longer adequate for the drone.
I can’t explain this to myself.

Perhaps it’s borderline OK depending on flight conditions.

Unfortunately some small and nervous oscillations are evident whereas before it was perfect.

I would expect further tuning would be required.

Certainly I was just wondering why this could happen. First everything ok and then, without changing anything, the tuning is no longer suitable for the vehicle which is always the same.
Thanks @dkemxr

Maybe you have a mechanical problem? Is the flight controller still damped as the flights before? Is there something who can get loose over the flights?

I had in the past a too soft damped flight controller. After rework the damping the problems very gone.

Hi @buckker,
the mecanic and software configuration of the two logs is the same, i do not changed anything…
Thank’s for your reply :slight_smile:

Can we see pictures of how everything is mounted? Is it possible that one of the motors became slightly twisted in transit?

One recommendation is to run auto tune in a progressive manner. Start with 05 wait for it to complete then do a .07 and then do a 0.1

Hi @smartdave,
i attach the photo of setup.
What exactly do you mean by twisted?
I do not understand…
Thank’s for your reply

When i did autotune i ran one axis at a time.
The thing I can’t explain is that it flew perfectly and then on November 5th these disturbance problems appeared.

Hi Friends,
Yesterday, before go to fly, i found a problem with right gimbal (pitch/roll) of my radio. I think it’s broken because it had abnormal impulses…Could this be the reason for the problem?
@smartdave @hosein_gh @xfacta @buckker @dkemxr

By looking at RCIN 1 & 2 i can say no

even if we compare ATT & DES values when FC didn’t get any input by radio