[emcq]

I used to work for a drone company. I made sure to go watch the mechanical testing for prop safety. One of the test objects was a chicken leg, and the prop cut through more than 2mm of bone. The props can do some serious damage!

I don't know what, if any, approaches are implemented but one solution is that you can design a safety feature in the motor control to turn off the motor if it detects blockage.