The motors are brushless motors and should last a long long time. However as with every moving part there is wear and tear. With the motors it's the bearings. Just keep check on the by doing a toucheE feallie test. See that they turn freely and all have the same resistanc. Turn the shaft a listen for any scraping sounds or for grinding. If you get any abnormalities change out the motor. If the feal tight and act the same turn and no bad sound keep flying. You will get where you can tell when one is different and acting up. When I change a motor I change the speed controller with it (ESC). To me it's cheep insurance to keep my bird in good flying order.
To test the ESC I make sure they power up and start and stop the props at the same time. I use a laser tach to check the rpm at idle and at high speed every one in a while. If one of the motors is 100-150 rpm difference I change out the ESC and test again. Keep good props and keep the battery contacts clean and any residue cleaned with alcohol. Wipe bird down with mild soap an water and check screws for looseness. Keep the batteries cycled at 20 uses and clean contacts. Other than that I fly and have a lot of fun. I do a lot of autonomous flights do to my terrain. Have two birds and have had no major problems. Only crashes were pilot error. And all minor. I just remember what goes up must come down and I want it to come down when and how I want.... Enjoy flying!
