Sikorsky S-76A N343AA accident near Santa Maria, California

Probable cause

The copilot's misjudged clearance from an object during a hovering turn for landing. Contributing to the accident were the inadequately marked heliport surface and the close proximity of an obstruction near the landing area.

NTSB analysis

The helicopter's copilot was performing the landing on an oil production platform and making a right pedal turn over the heliport surface when the tail rotor of the helicopter struck a movable derrick. The copilot lost tail rotor authority and landed immediately. The left main gear collapsed and the helicopter rolled onto the left side. The helicopter received structural damage to the tail rotor and main rotor assemblies. The operator reported that there were no mechanical malfunctions or failures of the helicopter. Six days before the accident, the movable derrick on the platform had been positioned to its closest location to the heliport area, 7 feet from the southeast edge of the heliport deck. None of the derricks on the other platforms used by the operator can be positioned this close to the flight deck. The deck area of the accident platform's heliport is 50 feet by 50 feet, compared to an area of about 70 feet by 70 feet on the other platform heliport decks. In the past, the accident platform had different markings than those on the other decks, including a reference line, or "Butt Line," to determine the location of the pilot seat that would allow adequate tail rotor clearance during a pedal turn. The deck on the accident platform had been stripped and repainted about 2 months before the accident, and the new markings were similar to those on the other decks; however, the "H" symbol was offset from the previous position to be about 1 foot closer to the southeast side of the deck, and the reference line had not been repainted.

Text from the NTSB. Open the NTSB docket for LAX08LA200 for the full record.