The National Transportation Safety Board faulted Heli-USA Airways maintenance personnel for a March 8, 2007, tour helicopter crash at Kauai's Princeville Airport that killed four people and injured three others.

An NTSB report released today said maintenance personnel failed to properly tighten a clevis pin fastener on the flight control servo and reinstall a functioning lock washer, which resulted in a complete loss of helicopter control by the pilot.

Contributing to the deadly crash was the company's failure to ensure its maintenance program was being executed in accordance with federal regulations, the report said.

Heli-USA officials could not be immediately contacted to comment on the NTSB findings.

The Aerospatiale AS350BA helicopter crashed as it was returning from a 45-minute tour flight. Pilot Joseph Sulak, 59, was killed, along with passengers John O'Donnell, 45, of East Rockaway, N.Y., Margriet Inglebrecht, 19, of Santa Maria, Calif., and Teri McCarty, 47, of Cabot, Ark.