Today will go down in my flight history. One of the six motors burnt out while flying over a residential area. I only avoided the crash because I am flying an X6 drone. If it were a quad, it would definitely crash into the ground, or worse, it would do property damage.
I am asking for help in finding the cause of the engine burning out during the flight. I have never faced a similar situation.
I would use MissionPlanner motor test to run some tests and see if the motor or the ESC get hot.Without temperature data it’s hard to tell whether it was the motor or ESC. It could even be an ESC fault that has now ruined the motor - or the other way around
Could be as simple as bearings in the motor - if so replace all bearings in all motors.
I did a test of the motor temperature with a pyrometer in a home condition 27° C. I used the motor test in Mission Planner for this. During 2 minutes at 50% throttle consumes 11A and heats up to 78 ° C. I made measurements in the area of bearings.
I have never used my drones or Helis commercially. I do not know the hours of each aircraft. I gave the motors usually a drop of Scorpion Motor Bearing Lubricant after about 6 flights. On the 30 ml Scorpion Bottle it says: Mil-C-81309E, Type II. Lubricant Made in USA.
I am flying as a hobby since 2010 and never replaced a bearing for heavy use. I have mainly replaced motors after a crash or started fresh with a newer or better aircraft.
I believe your practice will work but only with best quality gear.