What happened
On November 7, 2015, a Beech Super King Air 350, registration NA-302, operated by the National Airborne Service Corps, was performing an aerial survey mission in the Nantou and Miaoli regions. The flight crew, consisting of a pilot, co-pilot, and two survey technicians, was returning to Taichung/Qingshangang Airport.
During the approach, the crew noticed an anomaly with the landing gear indication lights, as only the nose gear light was illuminated. After performing a go-around, the crew attempted to extend the gear again. While the nose and right main gear lights eventually illuminated, the left main gear indicator remained unlit. Despite the lack of a positive indication for the left gear, the crew requested the tower to visually confirm the gear status. The tower reported that the gear appeared to be down.
As the aircraft configured for landing, the pilot extended the flaps to the full position, which triggered the landing gear warning horn. The crew, perceiving the warning and the light discrepancy as a false signal or a simple bulb failure, proceeded with the landing. Upon touchdown, the left and right main landing gear and the nose gear collapsed simultaneously. The aircraft subsequently performed a belly landing, sliding along the runway.
The investigation
The investigation conducted by the Taiwan Transportation Safety Board (TTSB) focused on the mechanical state of the landing gear system and the crew's decision-making process. Investigators discovered that a 2-amp circuit breaker controlling the landing gear power pack had tripped, which prevented the hydraulic power pack from building sufficient pressure to fully extend and lock the gear.
Furthermore, the investigation examined the crew's response to the landing gear warning horn and the discrepancy in the gear lights. The investigation also reviewed the training programs of the National Airborne Service Corps, specifically regarding emergency procedures and Crew Resource Management (CRM).