Recently purchased a Mavic Pro along with case etc. One of the items purchased was a set of spring loaded landing gear leg extensions. The Mavic would sometimes keep rising (or descending) after I released the control stick. (instant panic) If it was rising I could stop it by pulling the control stick down. And vice versa if it continued to descend. Didn't happen every time, maybe one time out of six or seven rise (or descend) commands. It would also periodically report sensor error or sensor recalibration required and land immediately. Generally after four or five minutes into the flight time. Recalibrated everything ...multiple times. I have owned a Phantom 3 standard and Phantom 3 Pro for many years and am quite familiar with the requirements.
Finally removed the springs in the landing gear extensions and no longer have any sensor error reports but would have sudden uncommanded change in altitude. On take off it would hover at three feet up for a few seconds and the jump up another three feet or so. Then do it again. Flew out over a field and hovered at thirty feet up. It would again, periodically, start rising on its own. By pulling the stick back I could stop the rise and fly it horizontally back to the home position. To descend I had to hold the stick back for about five seconds before it would respond. Once, while it was out about 150 feet from Home, I touched the Return to Home command and it started to rise to the 100 foot level pre-programmed for RTH altitude, but passed the 100 foot mark and just kept going up. Fortunately I was watching closely and again by pulling the stick back and holding I was able to stop the rise, cancel RTH and fly it back manually. Removed the remaining pieces of the leg extensions and no more problems. Have about two hours of testing and everything is normal. Put the leg extensions back on and all the problems returned. My thoughts on what is happening are as follows: with the metal springs installed the ultrasonic sensors malfunction. With the remaining plastic extension pieces, the optical sensors see them and get erroneous altitude readings.
Finally removed the springs in the landing gear extensions and no longer have any sensor error reports but would have sudden uncommanded change in altitude. On take off it would hover at three feet up for a few seconds and the jump up another three feet or so. Then do it again. Flew out over a field and hovered at thirty feet up. It would again, periodically, start rising on its own. By pulling the stick back I could stop the rise and fly it horizontally back to the home position. To descend I had to hold the stick back for about five seconds before it would respond. Once, while it was out about 150 feet from Home, I touched the Return to Home command and it started to rise to the 100 foot level pre-programmed for RTH altitude, but passed the 100 foot mark and just kept going up. Fortunately I was watching closely and again by pulling the stick back and holding I was able to stop the rise, cancel RTH and fly it back manually. Removed the remaining pieces of the leg extensions and no more problems. Have about two hours of testing and everything is normal. Put the leg extensions back on and all the problems returned. My thoughts on what is happening are as follows: with the metal springs installed the ultrasonic sensors malfunction. With the remaining plastic extension pieces, the optical sensors see them and get erroneous altitude readings.
