RICARDO CHEES
 lvl.4
Peru
Offline
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My Agras MG-1S suddenly lost control and slowly drifted away until crashing on to a small rocky mountain.
As this was a new location and the first flight of the day, I proceed with the RC to measure a small field for testing drop coverage for the client. The GPS signal was ok (14-16 satellites). A small rectangular area was measured and Calibration Point was set in an open location 2-3 meters from my position.
Weather was ok, the temperature:15-16 degrees, little to almost no wind. The flight was around 1130 am and 1 pm.
As the cranberry fields were located in a small valley, the field squares were separated every 80 meters by a 2.5 meters high net for protecting the crop from sand and dust. So the flight was planned with the OAR disabled. Also, the maximum distance limit set for the drone test flight was 200 meters taking into consideration that the border of the field was at that distance. The flight level was set at 2.5 meters and the line separation in 3 meters. RTH as usual 15 meters and maximum flight altitude at 16 meters.
So all in place in the RC, I proceed with the drone to extend and secure the arms, connect the battery and calibrate the compass. Then pour some water on the liquid tank and spray test until "Spraying Normally". All systems ok in the RC, good signals and checklist completed and ready to take off.
Once this all set, I take off for a short manual pre-flight - (F and M modes as usual) prior to the test flight to check if all systems were ok. I took the drone away from me in line about 60 meters, then change line and return toward me and the Calibration Point with the intention to land and refill the tank for starting the drop coverage test flight.
Suddenly at a distance about 4-5 meters away from the Calibration Point the drone suddenly stops, a message in the RC "NO POSITION", and immediately it started drifting very slowly, passed on top of my head at 2-2.5 meters above of me and continue slowly drifting away as if the wind had taken control.
No response at all from the drone to the RC. My first action was take away my hands from the sticks, no response, Then tried all the possible maneuvers, but no response at all. RTH no response and the drone drifting away very slowly at an altitude of 4 - 5 meters. No acceleration, no change in altitude, only slowly drifting away. I started following the drone the closer I could, but it started to move away from the field path and going diagonally across the fields. At one point I lost sight of the drone and tried as a last resource, "Failsafe". So I turned off the RC to try a failsafe command for returning home or even stopping drifting away by restarting the RC. My last hope was a battery low warning and the drone coming down in a controlled manner in an even terrain. But the battery was almost fully charged.
I decided at that point to return to my truck for starting the search and recovery procedures, as I walked for about 300 meters away following the drone. As walking my way back, an Engine Failed message appeared in the RC, so I knew then that the motors stopped suddenly.
We tried to follow the path and then turn left towards the small mountain because I knew that was where the drone was heading the last time y saw it. We found the drone in a vertical position and the edge between the small mountain and the road bordering it. Two motors were sunken deep into the sand and gravel, one oval arm was broke, 15 blades were broken, two RTK antennas covers were separated from their bases. Apparently, no damage in the spraying system, tank, landing gears, pumps, hoses, 8 foldable arms, microwave radars, OAR and drone head, were ok.
It looked very bad.
Now I have to replace 15 blades, 3-4 motors, an oval arm. The RTK antennas are only the metal tubes covers that can be repaired, and I don't have the RTK at all. The estimated cost in parts is about $1,300 USD.
I downloaded the flight log from the drone to the DJI 2 Assistant v.13 in my PC and a 37 Mb DAT file was sent in ZIP to DJI Support in China. The reply they couldn't open the file so I tried again but no luck, they insist that it's not possible to open the file.
I don't want to put more money in a product that may be unreliable and can cause a serious accident o harm to third parties if flying near roads or small buildings or even losing it in a vast and dense crop. Hope you help me with establishing the cause of this accident. I'm an experienced pilot, flying Agras since Novembre 2017 and done nothing different than I usually do when operating the last year an a half. Only once the drone was unresponsive last year but I was in a very large open field, no obstacles at all and I was able to control and land the Agras safely almost right away.
Hope you can help me with some answers.
Attached some pictures and schematics about the site.
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First Officer