Alright guys, my P3A was flying an autonomous mapping mission earlier today. After it finished the mission and was returning to me, when it got closer I could noticeably hear that the motors were reving up and down. When I could see it clearly, they were surging enough to cause some very erratic flight. Once it arrived overhead I quickly switched it from "F" to "P", took over and landed quickly and safely. I uploaded the flight file to healthy drones and on the leg home you can see where the battery volts/amps were surging up into the 15/20 range then back down below 15. Anyone have any idea what was going on and what I need to do going forward??? Thanks!