I crashed my P34k from approximately 30 or about 10 meters. I hit a post trying to land on a porch and well then it tried to compensate for the prop breakage and while trying to stay in the air hit a brick wall and fell to the pool deck from there. Visually stunning and sounding crash. Unfortunately no video it was just a test flight. I was testing the visual part of the auto flight to see how well it would do inside. I failed and the visual part failed. However after the crash I put two new props on. the two new props were carbon fiber after market upgrade props. with two original DJI props. The two new were on the port side of the quad and the original props were on the starboard side. I had trouble with the threading concept and could not get one prop threaded on for a few attempts. As soon as I told the quad to auto rotate for hover it attempted to take off from ground level. It immediately flipped onto the rotors and was driving itself into the ground as hard as it could and I could not get it to turn off. I had to grab it by the upturned legs and then manually remove the battery to stop the motors. My question is this ---- Should I have put the same four rotors on. Do the rotors have different weights based on type and the quad could not compensate for the difference thus flipping it on to it's back due to the rotor imbalance. Also is there and emergency shutoff in the DJI app somewhere I could not find it however holding a twisting fully revving quad in one hand and trying to find something on a small phone in the other may have been the other operator issue. I have new rotor guards installed just waiting on the new rotors to be delivered before next test flight. I am just hoping that I don't wreck more props. Do I need to worry about an ECU or Battery issue? any experience would be helpful. Couldn't find props locally to Dawsonville Georgia we bought the last pair from Fry's in Milton why I only had two new and two old when it flipped. Also I did note the silver hub versus the black hub colors on the old and the carbon fiber do those colors mean anything should I have done a kitty corner thing with the silver and black hubs? Sorry for the long post trying to be as thorough as possible for best answer reults.

I would not recommend combining different props, but I would assume that the controller would compensate for small differences between them.
Since you had problems with the threads, didn't you but two identical (CW, CCW) props on it? This would explain flipping.
Next time use the CSC command (http://wiki.dji.com/en/index.php ... Stopping_the_Motors) to turn off the motors. But I have seen occasions where CSC didn't work and I had to remove the battery.  

What I would do is put the left stick in the down locked position.  Then calmly walk over to the upside-down quad, pick it up firmly by the vertical legs - preferablly with both hands - pick it up and hold it right side up and slightly above eye level, and hold it very still.  It should shut off in about 3 secs.  

It would not occur to me to mix props.

You'd do yourself a big favor my reading the manual a couple times - from top to bottom - slowly and carefully.  

It seems to me that if you are not aware of the differences in the props (hub colors), you need to get more familiar with the aircraft and manual before flying. The props on alternate corners have different threads and blade pitch (they rotate in opposite directions in use).
The CSC command (look it up in the manual) is the way to shut down the motors in an emergency except I have heard that it may not work when the AC is inverted such as yours was. In your situation I would probably run over, grab the AC and pick it up off the ground/flip it over to free the motors and then shut the battery down as a first choice or pull the battery as you did. Not sure if pulling the battery when powered up could cause any problems with the electronics.

KM5RG-Robert Posted at 2017-3-31 05:46
It seems to me that if you are not aware of the differences in the props (hub colors), you need to get more familiar with the aircraft and manual before flying. The props on opposite corners have different threads and blade pitch (they rotate in opposite directions in use).
The CSC command (look it up in the manual) is the way to shut down the motors in an emergency except I have heard that it may not work when the AC is inverted such as yours was. In your situation I would probably run over, grab the AC and pick it up off the ground/flip it over to free the motors and then shut the battery down as a first choice or pull the battery as you did. Not sure if pulling the battery when powered up could cause any problems with the electronics.

Thank you for that answer.