PRINCEVILLE, Kauai » Federal investigators said the 2007 Heli USA crash that killed four people was caused by shoddy maintenance that caused part of the flight controls to come apart.

In the National Transportation Safety Board report released yesterday, investigators said a worn washer, coupled with the lack of torque on a nut, allowed the servo, part of the flight control mechanism, to completely disconnect itself from the transmission.

But the owner of the company continues to believe the crash was caused by faulty engineering from Eurocopter, the manufacturer of the A-Star helicopter that crashed.

Nigel Turner, chief executive of Las Vegas-based Heli USA, said he was on the phone with NTSB investigators as soon as he read the report, “;asking (them) what the hell is going on.”;

Turner, himself a pilot, said that while the nut in question was not torqued to the company's specifications at the time of the crash, Eurocopter put out a bulletin later telling maintenance workers that they should use the lower torque because the servos were cracking under the high pressure.

“;The poor mechanic is sweating, and the torque he put on the bolt was OK,”; Turner added.

The report also claimed that Heli USA was not following maintenance guidelines and was using old manuals to fix their A-Stars. Also, flight checks performed after maintenance were not being done properly, and training for the mechanics was not done according to federal guidelines, the NTSB said.

Turner, however, said the his mechanic had more than 20 years' experience working on A-Stars and that his operations were safe.

The report also indicated that the pilot, Joe Sulak, with 30 years of experience, had no control of the helicopter at the time of the crash.

Sulak was one of four who died in the March 2007 crash at Princeville Airport. Also killed were passengers John O'Donnell of East Rockaway, N.Y.; Teri McCarty of Cabot, Ark.; and Margaret Inglebrecht of Santa Maria, Calif.