A Maui tour helicopter that crash-landed onto a canopy of trees on Jan. 10, 2006, was brought down by loss of engine power due to a fatigue failure of a turbine blade, according to a National Transportation Safety Board report.

The pilot of the Sunshine Helicopters Eurocopter AS350BA broke his ankle, but four passengers escaped serious injury.

As a result of an investigation into the engine failure, the Federal Aviation Administration and engine manufacturer Turbomeca issued airworthiness advisories regarding the service life and maintenance of the part, according to the safety board.

Sunshine Helicopters' Ross Scott said the NTSB report gives the air tour operator "a clean bill of health."

The report said the helicopter departed from Kahului Airport and was exiting Manawainui Gulch near Kaupo about 45 minutes into a one-hour tour flight when the aircraft shuddered and the low-rotor-rpm warning horn sounded.

The pilot entered an autorotation to slow the helicopter before settling into the treetops. The aircraft came to rest on its right side, suspended in the trees a few feet from the ground. The passengers and pilot lowered themselves to the ground and called for assistance using a cell phone.

Inspection of the engine determined that a turbine blade from the second-stage gas-producer turbine had separated from the turbine wheel as a result of a fatigue fracture, the NTSB said. The part, which had a service life of 6,000 hours, had been in service 2,986 hours at the time it was used as a replacement part during a 2004 overhaul, the report said. Turbomeca has since reduced the service life of the turbine blades from 6,000 hours to 3,000 hours.

NTSB accident reports are available at www.ntsb.gov/ntsb/query.asp.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.