What happened
On June 6, 2012, a Sikorsky S-58ET helicopter, registration OB-1840, operated by Helicusco S.A., crashed into the mountainside of Cerro Mama Rosa (Nevado Ancahuarakana) in the Quispicanchis province of Cusco, Peru. The aircraft was performing a commercial aerial support mission for Nueva Esperanza Hydro (NEHYSA), involving flyovers and landings along the Inambari River.
After completing several exploratory flights in challenging weather conditions, the crew performed a final refueling in Mazuco and departed for Cusco at 21:46 UTC. During the return leg, the aircraft reached altitudes exceeding 15,000 feet on multiple occasions. At approximately 22:23 UTC, the helicopter impacted the terrain at an elevation of roughly 16,295 feet. The impact caused the aircraft to disintegrate and catch fire, resulting in 14 fatalities, including the two crew members and 12 passengers.
The investigation
The investigation by the CIAA examined the flight logs, maintenance records, and satellite tracking data from the Skyconnect system. Investigators reviewed the operational history of the day, noting that the flight schedule had been delayed due to poor weather. The investigation also looked into the aircraft's performance limitations, specifically regarding maximum altitude capabilities, and the crew's decision-making regarding refueling and flight continuation despite deteriorating conditions.
Findings
- The aircraft was operating in a manner that exceeded its standard daytime VFR (Visual Flight Rules) certification, as the return flight occurred during nighttime conditions.
- The crew performed a flight leg with a limited fuel load (approximately 470 lbs) following a request from passengers to proceed with the mission.
- The aircraft reached altitudes of over 15,000 feet, which approached the manufacturer's stated performance limitations for the aircraft's weight.
- The primary cause of the accident was controlled flight into terrain (CFIT) during a night flight under visual flight rules.