The National Transportation Safety Board has concluded that a helicopter that crashed during a sightseeing tour in March 2007 on Kaua'i killing one person and seriously injuring three others was probably caused by a manufacturing defect.

That defect likely resulted in separation of the tail rotor system and total loss of tail rotor control, according to the the NTSB report.

"A contributing factor to the accident were (sic) the trees that the helicopter struck during the autorotation," the reported stated.

According to an earlier NTSB report, a McDonnell Douglas 369FF helicopter operated by Inter-Island Helicopters Inc., sustained substantial damage when it impacted trees and terrain in Ha'ena, Kaua'i, during a commercial air tour flight on March 11, 2007.

The flight departed the Port Allen Airport on a 55-minute sightseeing tour of Kaua'i. During flight near Tunnel Beach in Ha'ena, the tail rotor output shaft and the tail rotor blades separated from the tail rotor gearbox and fell into the ocean. The pilot executed an autorotation to a YMCA campground that was located next to the beach.

The pilot received minor injuries; however, the right front-seat passenger was killed, and the three other passengers received serious injuries, according to the earlier NTSB report.

Michael Gershon, 60, Walnut Creek, Calif., died in the crash.

The three injured passengers were Dania Hansen, 60, of Los Altos, Calif.,and Douglas Barton, 60, and his wife Judy Barton, 51, of Newport, N.H.