LIHU'E, Kaua'i —Wreckage of last week's Heli USA tour helicopter crash, which killed four people, suggests the aircraft's inflatable floats did not play a role in causing the accident, an investigator with the National Transportation Safety Board said.

Instead, it appeared the helicopter took a sudden, catastrophic lurch nose-down as pilot Joe Sulak, 59, of Princeville, was conducting an emergency landing with reported hydraulic problems, said NTSB investigator Brian Rayner.

Three passengers and Sulak died and three passengers are being treated for severe injuries at The Queen's Medical Center.

"Our best estimate is that the floats deployed as a result of collision with terrain. It appears that the helicopter struck the ground, (then) the floats deployed," he said. The presence of the inflated floats under the wreckage had confused company officials and others, who suggested that if they had been inflated in flight, they could have contributed to the crash.

Rayner, who is the NTSB's lead investigator on the crash, said Sulak reported by radio to the Heli USA dispatcher at Princeville Airport that he was experiencing hydraulic problems and planned to perform a run-on landing — the accepted procedure when an A-Star helicopters' hydraulics are out. Since it is difficult to perform the fine control needed for hovering a helicopter without hydraulic assistance, the run-on landing involves a pilot bringing the helicopter to the ground with forward speed and sliding to a stop on its skids.

A single witness to the crash told investigators that the aircraft was coming in at a downward angle, but suddenly tipped forward at the last moment and crashed on its nose. During the process, there may also have been damage from the main rotor striking part of the helicopter body.

"There was some evidence of blade impact, but the most significant deformation was crush deformation," Rayner said.

He said there was no evidence of clay or grass stains on the floats, suggesting they had not been inflated when the helicopter hit the grassy shoulder of the Princeville Airport runway.

Rayner warned that the investigation is still very young and considerable data need to be gathered. Rayner said he expects to file a preliminary report in about a week. Final reports can take a year or more to complete.

LATEST COPTER CRASH

Rayner's crew and FAA officials also conducted the preliminary investigation of a second fatal helicopter crash Sunday, in which an Inter-Island Helicopters Hughes 500 lost its tail rotor while flying over Ha'ena — perhaps due to an impact with a bird or other object.

Pilot Donald Torres, 30, of Hanapepe, brought the spinning helicopter to the ground, but it clipped tree limbs and hit a fence at the last minute, and fell onto its side. One passenger was killed and three were injured. Torres suffered minor injuries and was treated and released from Wilcox Hospital.

Michael Gershon, 60, of Walnut Creek, Calif., died in the crash. The other passengers were Dania Hansen, 60, of Los Altos, Calif., who had been scheduled for surgery yesterday at Wilcox Hospital, and Douglas Barton, 60, and Judy Barton, 51, both of Newport, N.H., who were flown to The Queen's Medical Center for treatment.

Rayner said he will pass off information on the Inter-Island crash to a separate NTSB crew that arrived on Kaua'i yesterday. That crew is expected to be headed by Chicago-based investigator Jim Siliman.

In the latest crash, Rayner said witnesses interviewed by his team, FAA investigators and police said they heard two loud bangs, and saw at least two objects leave the helicopter and land in the ocean. Fire Department divers yesterday recovered helicopter parts from the waters off Ha'ena Point.

Rayner said the parts may provide some indication of why the helicopter's rear rotor and attached parts broke off the tail of the aircraft.

BIRD TO BLAME?

"The majority of the tail rotor gearbox, output shaft, control linkage and tail rotor were no longer installed on the helicopter" when he inspected it on the ground, he said. Inter-Island Helicopters vice president Ken D'Attilio suggested the helicopter might have run into a large bird that caused the damage.

It is not unusual to have bird strikes on aircraft, and Rayner said he has experienced them himself as a military helicopter pilot. But he said investigators will look for physical evidence to find the cause of the damage.

Many residents and visitors in the area looked up after hearing the bangs, and then reported hearing the helicopter engines begin roaring.

"Engine noise increased significantly — one said it was like a car with a very bad muffler, loud," Rayner said. They reported the helicopter began descending in a controlled way, but with the rotors "teetering back and forth." As it crossed over the beach and the tree line, the helicopter began spinning, and it continued rotating until it hit the trees and then the ground, he said.

The pilot's job of controlling an aircraft with a tail rotor gone is extremely tough, he said.

"It is a significant in-flight emergency. This pilot was dealing with a very, very significant emergency," he said.

Siliman's crew will begin a detailed analysis of the Inter-Island helicopter wreckage today at the crash site in Ha'ena.

FIRST WRECKAGE MOVED

The wreckage of Heli USA's A-Star was moved Sunday to a hangar at Lihu'e Airport. The wreckage of the Inter-Island helicopter is expected to be moved there as well later this week, once the crash site investigation is complete.

Rayner said neither helicopter carried equipment that would record instrument functions and neither carried cockpit voice recorders.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.