What happened
On February 7, 2020, at approximately 10:13 AM, a Sky Arrow 55 unmanned aerial vehicle (UAV), operated by Jingwei Aerospace Technology Co., Ltd., experienced an engine failure during a flight test near the Lanyang River estuary in Yilan County. The aircraft was performing an aerial photography mission for the Forestry Bureau's Forestry Aviation and Surveying Station.
After taking off from the Yilan University South Campus experimental airfield, the aircraft climbed to 600 meters and transitioned to automatic flight mode. At 10:11 AM, the engine RPM dropped from 2,500 to zero, causing the aircraft to begin a descent. The internal operator attempted to manage the descent by reducing airspeed to extend the glide range, while the external operator eventually switched the aircraft to manual mode to attempt a recovery. However, the aircraft's flight path led it to strike the eaves of the Kaixuan Junior High School gymnasium. The impact caused the aircraft to catch fire and destroyed the gymnasium's roof structure. There were no fatalities or injuries.
The investigation
The Taiwan Transportation Safety Board (TTSB) examined the Ground Control Station (GCS) logs, flight control computer data, and the wreckage. Physical inspection of the engine revealed that while the left cylinder was partially intact, the right cylinder was seized, though the exact cause of the failure could not be determined due to fire damage.
The investigation also reviewed the operator's procedures and training. It was noted that the mission was being conducted a day earlier than the officially approved NOTAM window, and parts of the flight path were outside the authorized airspace. Furthermore, the investigation looked into the GCS interface design and the effectiveness of the emergency protocols provided in the operator's manual.