OK, here is the full story. I planned on a short flight to get a photo of my house. I flew straight up to 419 feet, turned off the video recording in order to make a still shot, then started a descent. I did not turn on the video again since I intended to land. While descending at about 200 to 250 feet, the Phantom suddenly flipped over perfectly upside down and accelerated towards the ground. I noticed the rapid fall and quickly applied full power to stop the fall, not realizing the drone was upside down. Of course, this only added more speed to the fall. The drone smacked the ground flat on its top and propellers and bounced. When I got to it, I expected to find a pile of rubble but there it lay, all lights on, strobes blinking and the battery still intact showing 3 green LED's and one blinking. All four props were broken and the top shell had damage on two of the motor arms. I photographed the site and videoed it for reference then took the drone inside, cleaned it up, replaced the propellers and inserted a different battery. It powered up immediately, giving me a gimble motor bind or something like that. The Phantom's camera worked fine and I made a photo inside the house with it. I then decided to try it out, took it back outside and turned on the iPhone video camera to record the startup. The drone fired up normally, sitting there idling. I applied a little power to raise it to about three feet and tested the left stick controls, worked fine. I flew it to about ten feet and tested the right stick controls and again all worked fine. I believe I then landed and inspected everything noticing the gimbal mount was binding. I flew it a couple more times for short flights only. I then went back inside and calibrated the gimbal mount and got it to working part of the time but it was still binding when going from level to vertical down. I contacted DJI and got authorization to send it for repair. It reached DJI Monday of this week and was repaired and returned yesterday!!!!! Total cost was $239.00. I was impressed at the speed of repair however I requested many times and through many different channels for someone to explain how this crash happened. My flight data logs on my iPad mysteriously stopped recording on November 27th and started back January 19th but the crash was January 21 and the flight was not recorded. I have gotten on DJI's forum and asked for information about this situation and what happened to the flight logs and no one has any answers. I am still waiting on DJI to "get back to me" with their side of what happened but I know for sure that it was not pilot error for I was doing nothing but descending. The drone did not hit anything unless it was a bird and the weather was fine. It was 69.9 degrees, winds out of the SSE at 3 MPH. I did not record the barometric pressure but I do have that data on my weather station if needed but there were no weather systems approaching so I assume the pressure was fairly stable.
I expect my Phantom to be here Thursday and I will indeed carefully check it out at low altitude before I am reasonable comfortable with it again. I do hope DJI will give me their version of the crash but I have already guessed it will be pilot error, since I paid the bill without question. My question to the group is: What caused a perfectly healthy Phantom 4 to suddenly do a perfect flip to the upside down position unless something internal malfunctioned? Can anyone make their drone flip over to that position??? Nope I think not, not that anyone would try but any drone flyer knows that they are inherently stable and should recover from most any flip over at altitude if nothing went wrong. On one occasion, I foolishly hoovered my drone about five feet to test its "lifting power" by tugging on one of the landing struts. It resisted the pull and fought to keep its condition upright. I did feel the strength of the motors and the power of the drone to right itself if tilted. So, what else could have caused this crash?
I appreciate anyone's questions as I struggle to find out the cause before I attempt to fly it again.
Thanks a bunch!
Jim
WA5TEF