Hello,
So I logged more than 300Km on my Mini 2. It still flies perfectly, and it never had a crash at all. But now I'm a bit concerned about the propellers. I visually check them, and their screws, before and after each flight, and I see no change; but how can I know if the screws are still fully locked? They still look OK, but what if one or more are starting to unscrew themselves? Normally I would just slightly tighten them with a screwdriwer, and so I would notice if they were getting loose. But these have thread locker: if I tighten a screw that's still good, I will break the thread locker.
So what should I do? Is the basic visual inspecion enough, or should I just replace the propellers (and screws) after so many flights, even though they're still good?
And what thread locker should I use? I've read that many types do not harden when used on aluminum...

Thank you
Cristian

A visual check is all thats needed,   the thread locker is the dry type that pre applied to the screws before they are fitted.     I had 4000km on my mini before I changed the props and the screws never worked loose.    When you do need to change the props use the screws they are supplied with and they are pre applied with the right thread lock.

I use to check each propeller blade by gently moving it up and down. This far each blade is equally "loose". If a thread locker was broken and the screw had began to unscrew I'd notice the difference for that blade.

Thank you very much. I'll keep doing what I've been doing, then... Thanks again and happy new year!

If a screw is not fully home then it needs to be tightened irrespective of whether or not the tightening would break the thread locker. ( Might the bonds reform or is it a one time only bonding? )
If a screw is fully home then I doubt that the amount of twist you might get in the thread would break thread lock.
When checking mine I try "nipping them up" and if they don't move under that torque I am satisfied they are fully home. Unfortunately judging how tight is tight enough is subjective, I wonder do DJI actually tighten them to a specified torque?
Given the size of the threads it can't be a lot lol and suspect that that is part of the reason the screwdriver handle is so 'blooming' small.