I was returning from my personal best range test, 10,159 ft /1.92 miles, 20,470 ft/ 3.87 miles round trip and as I was landing I noticed a lot of noise from the bird. There was motor separation, the clip was still on the bottom of the motor shaft so I assume the top of the motor came loose from the shaft. I had completed two back to back range tests a few hours before and I didn't notice any excess heat from the motors when I removed the props at that time. After the motor went bad, I checked the props to make sure they were not out of balance, and they were fine. I would like to know what happened, has anyone had this issue before? Lucky from me until the replacement motor arrives, my trusty P3 Standard has loaned me a motor so I can keep flying and complete more range tests. BTW, the tape on the arm was temporarily holding one of my navigation lights on and there is nothing wrong with the arm.