While not assigning blame for the sudden plunge of the Agusta A119 on June 30, 2005, the preliminary report, released in late November, focuses on the fuel control unit, manufactured by Honeywell.

A five-member NTSB panel in Washington, D.C., will make a "probable cause" determination of the reason for the crash in the coming months.

Problems with the fuel control unit, which feeds fuel to the engine, included a gap found on the mating flanges, with a retention bolt "disengaged." The bolt was too short for that location, according to an examination by the manufacturer of the engine, Pratt & Whitney Canada.

Marc Hemmings, who examined the unit for Pratt & Whitney Canada, also discovered shearing in the bolt-hole area consistent with pulling and rubbing. Evidence of partial shearing before the crash also was found.

Hemmings, reached Friday, referred questions to legal counsel. A Pratt & Whitney Canada spokeswoman did not return a call requesting comment.

Honeywell, an aerospace manufacturer based in South Bend, Ind., also examined the fuel control unit and blamed the damage on "heavy impact" - the crash itself. A Honeywell spokesman confirmed the company manufactured the fuel control unit. The spokesman, Bill Reavis, said he was not prepared to comment on the NTSB report.

Fuel control units were twice replaced on the helicopter, once in 2002 and again in 2003. No reason was given on either occasion.

The accident, which occurred 7.5 miles northeast of Mancos in a meadow of skunk cabbage, killed pilot Jim Saler, 40, and flight nurses William Podmayer, 49, and Scott Hyslop, 33. Their deaths were followed by emotional funerals and an outpouring of support from community members.

The victims' widows, who have retained legal counsel, await the NTSB's final determination of the cause.

"The report confirms what the three families already knew, that it was a mechanical failure, and hopefully the probable-cause (finding) will confirm that," said Elizabeth Ceilley-Hyslop, the widow of Scott Hyslop.

"Our main concern is that there does seem to be some kind of manufacturing defect with the fuel control unit," Ceilley-Hyslop said. "I think somebody needs to be accountable for what happened."

Ceilley-Hyslop said Pratt & Whitney and Honeywell need to look at other helicopters to determine if problems with fuel control units are widespread.

The other widows, Judy Hill and Janet Saler, did not return telephone messages requesting comment.

No problems were found with other parts of the helicopter, the NTSB said. Jim Saler's autopsy revealed no alcohol or drugs in his system, and he had logged 1,600 flight hours as the pilot in command, 130 of which were in the Agusta A119.

The crash occurred in clear weather of about 80 degrees Fahrenheit with light wind. The accident site was at 9,731 feet elevation, the NTSB said.

NTSB investigator Arnold Scott, based in Denver, did not return messages requesting comment Friday.

Three other Agusta A119s have crashed, all within the last six years. The A119, known as the Koala, has been sold since 1989.

In a nonfatal 2004 accident, a pilot in Big Bear City, Calif., crashed at 8,800 feet elevation when he slowed the helicopter to 20 knots. A 2002 Florida crash occurred when a fatigued tail-rotor blade fractured, sending parts of the rotor flying and slamming the helicopter into a cow pasture.

A 2001 crash in Ogden, Utah, resulted from the manufacturer improperly rigging the rotary differential variable transformer, resulting in incorrect fuel scheduling to the fuel control unit.

Tri-State CareFlight, based in Bullhead City, Ariz., continues to fly the Agusta A119, including one that currently serves Mercy Regional Medical Center. Corrin Koehler, chief operating officer of Tri-State, said the A119 was "absolutely" safe.

Koehler said Tri-State was awaiting the accident's still-undetermined cause. "No one has been able to get a lot of closure on it," she said.

Dustin Duncan, a regional director of the Association of Air Medical Services representing the Rocky Mountain area, said he was not aware of any air ambulance company other than Tri-State using A119s in Colorado, Utah, Wyoming or Montana.

Approximately 650 helicopter ambulances that respond to emergencies operate in the United States, according to the Association of Air Medical Services, a group that represents the industry. Eighty-three have crashed since 2000, killing 66 people.

On the flight that ended in the Mancos crash, Saler, Podmayer and Hyslop had been dispatched to search for a 14-year-old drowning victim in Farmington. While returning to Durango, the flight was redirected to the Red Arrow Mines area on the west side of the La Plata Mountains to help a logger who had been injured in a trucking accident.

Upon arriving at the landing zone in the Helmet Peak area, Saler made a low pass before circling around to make his approach, according to a volunteer firefighter quoted in the NTSB report who was directing the landing from the ground.

The helicopter was about 220 feet above tree level when "it dropped straight down," said the firefighter, who reported hearing no unusual engine sounds.

photo JERRY McBRIDE/Herald file
Montezuma County Sheriff Gerald Wallace walks to the crash site of the Tri-State CareFlight Agusta A119 helicopter that crashed northeast of Mancos on June 30, 2005, killing three Durango men. An investigation into the crash focuses on the fuel control unit.