Taiwan's Aviation Safety Council (ASC) has issued several safety recommendations following the fatal crash of an Airbus Helicopters AS365 N3 Dauphin on 11 March 2016, faulting both Airbus Helicopters and the National Airborne Service Corps (NASC) for the accident.
The accident occurred in overcast conditions when the helicopter, which bore registration NA-107, was winching a member of the coastguard onto a ship grounded off the northern tip of Taiwan at Shimen, says the report. There were five personnel aboard the helicopter at the time of the accident: two pilots, the crew chief, and two coastguard personnel.
As the crew attempted to lower the first coastguard operative onto the ship, the Dauphin began to yaw sharply, before starting to spin rapidly. This threw the coastguard member on the winch into the main rotor, causing fatal injuries. The helicopter then crashed into the sea and was destroyed, killing the pilot and causing serious injuries to three other personnel.
Investigators attribute the crash to a pitch control malfunction in the tail rotor, stemming from wear and tear in the tail gearbox control-rod bearing. The aircraft involved in the crash was delivered on 21 October 1999, Flight Fleets Analyzer shows.
"The bearing wear continued, which spalled off the inner ring shoulder, completely detached the outer ring, and eventually led to the malfunction of pitch control in the tail rotor bearing," says the ASC.
"Due to the failure of the tail rotor pitch function, the pilot could not control the flight direction. Flying at a low altitude and driven by large horsepower, the main rotor was damaged from impact. The flightcrew could no longer perform relevant emergency procedures according to the flight manual and eventually lost control and crashed into the sea."
The report blames oversights by both Airbus Helicopters and the NASC during routine maintenance for not detecting the issue. It recommends tightening maintenance procedures, improved training, and other safety initiatives.
In April 2015, Airbus Helicopters announced that it had secured a fleet support contract from the NASC. The five-year agreement covered 10 AS365 rotorcraft used in search and rescue, disaster relief, emergency medical services, transportation, monitoring, and patrol missions.