3DR Solo – Accident – 2017-06-22

Drone Manufacturer: 3DR
Drone Model: Solo
Country: United States of America
Type: Accident
Date: 2017-06-22
Applies: Daytime
Pilot Qualifications: Unknown Status
Pilot Flight Experience: Unknown Hours
Link to External Information About This submission: https://www.safecom.gov/safecom/17-0431
File Uploaded: None


Over a 3 day period I experienced multiple instances of GPS signal loss during flight. The GPS signal losses were experienced by 2 different aircraft. After the first day of issues, I checked the FAASafety.gov website and discovered that there was GPS interference testing in the area. On the second day of flights, flying was not scheduled to begin until after the GPS interference testing was completed for the day. However, both aircraft still experienced GPS signal loss during flight. One of the aircraft had the upgraded mRobotics GPS and had 22-26 satellites locked when the signal loss would occur. While not noticed during the first flights that had GPS issues, during the latter flights the GPS issues always occurred when the Solo app showed no RSSI prior to take off, but the controller had normal RSSI. It is unclear if the GPS interference testing affected the flights, or if there was another factor that can be observed whenever the tablet displays no RSSI during pre-flight checklist.There was also significant rain during this week. In between showers, the decision was made to attempt to launch the aircraft. While running the pre-flight checklist, it began to lightly drizzle. When attempting to arm the motors, only 3 motors armed and began spinning. The fourth motor would not spin, and the flight was aborted. The next day, the aircraft was tested and all 4 motors were able to arm and the aircraft was able to fly. Later that day, another aircraft had just begun to fly a Tower mission when it began to rain. The mission was cancelled, and the aircraft was returned to the launch site and landed safely, although something was seen flying off the aircraft as it landed. Upon closer inspection, it was observed that both the #3 and the #4 propellers were missing, and presumably spun off at a high rate of speed when the motors disarmed. After waiting for the rain to stop, another mission was planned for the aircraft, however the aircraft would not power on. Pressing the power button would illuminate the battery lights momentarily, a “click” could be heard and the #1 motor moved slightly, but then the battery lights turned off. After further diagnosis, it was determined that the #1 motor had failed and needed to be replaced. This was confirmed by removing the motor, which allowed the aircraft to power on.

For the GPS signal loss issue: 1. During flight planning, check the FAASafety.gov website {https://www.faasafety.gov/spans/notices_public.aspx} for public notices concerning flight advisories {GPS interference testing, VIP movement, etc.}. 2. If there is no RSSI signal on the Solo app, but a normal RSSI on the controller, be aware that there may be GPS signal loss during flight. 3. If there is GPS signal loss during flight, and the aircraft exhibits erratic flight behavior while in Fly mode, switch to Fly Manual and land the aircraft. Do not land in Fly mode if the aircraft behaving erratically.Concerning operations in wet conditions: 1. Do not operate in rainy conditions, even if it is only light precipitation. In the 2 instances noted above, 1 or more motors stopped when exposed to wet conditions.

Reported Cause

Erratic control and loss ofGPS.