Small UAS; Multi Rotor
Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem
Aircraft; Software and Automation
Acceptance flight for new UAS was being conducted in the field with LAANC authorization.  Since this was a first flight; the vehicle was placed in a hover approximately 15 feet for observation.  After approximately 1 minute and with no control input from the RPIC (Remote Pilot in Command); the vehicle went into abrupt left graveyard spiral.  This is the expected flight behavior for motor failure in a quad configuration.  The failed motor was identified on postflight inspection and replaced with a spare motor.  Subsequent flight exhibited the same motor failure after approximately 3 minutes; however there was no damage due to keeping the vehicle in a low hover.  Operation Center was notified of the event. Tech support from the manufacturer revealed that the vehicle software was not properly matched to the controller software.  A field software update was applied and subsequent fixed; low hover testing was successful for approximately 10 minutes.  Build up testing was accomplished to demonstrate the vehicle to be fully mission capable.1) Future acceptance testing (first flights of a vehicle or new config) should follow the procedure used today.  Fly in a fixed; low hover for several minutes to validate vehicle stability before conducting further checks.  2) This incident highlights the importance of ensuring proper software configuration on components of the system:  flight controller; gimbal; ESCs (electronic speed controller); and controller.  Although the manufacturer had been involved with a software update the previous day; even they missed verifying this configuration with us until it was revealed on the acceptance flight.
UAS Crew was conducting a test flight when a motor failed after two separate flights. Software was found to be out of date and after update UAS flew without issues.