NEW ORLEANS (AP) -- Investigators have found evidence that a bird may have struck a helicopter before it crashed into a Louisiana swamp last month, killing eight people, the National Transportation Safety Board said Monday.
The NTSB hasn't identified the cause of the deadly crash near Morgan City on Jan. 4, but said tests on the wreckage of the Sikorsky S-76C found microscopic bird remains of a "hawk variety" on the pilot's side of the chopper's windscreen.
Investigators also found parts of feathers under a windscreen seal and in an engine, the NTSB said in a press release.
The helicopter, owned by PHI Inc., was carrying workers to a Shell Oil Co. platform in the Gulf of Mexico when it crashed about 100 miles southwest of New Orleans. The crash left a lone survivor critically injured.
A Department of Agriculture bird specialist examined the wreckage last month and didn't see any visible evidence of a bird strike, but tests at the Smithsonian Institution Feather Identification Lab revealed the microscopic bird remains. A DNA test showed it was a variety of hawk, according to the NTSB statement.
PHI had replaced the helicopter's original glass windscreens two years before the crash, "as part of their normal procedures," and replaced them a second time due to "cracking" in the windscreens about a year before the crash, the NTSB said.
A PHI official said he couldn't comment because the company is aiding in the crash investigation. A Sikorsky spokesman didn't immediately return a call for comment Monday.
Earlier this month, the NTSB said the helicopter's voice recorder captured a "loud noise" in the cockpit shortly before it plunged into the swamp, but didn't elaborate on the nature of the noise.
The NTSB said Monday it will continue to analyze information from the chopper's cockpit voice and flight data recorders. The investigation also will include "research into the potential scenarios that could cause the loss of engine torque and electrical anomalies noted on the flight recorders," Monday's release said.
Two of PHI's pilots were killed in the crash: Thomas Ballenger of Eufaula, Ala., and Vyarl W. Martin of Hurst, Texas.
PHI identified the other victims as Andrew Moricio and Ezequiel Cantu of Morgan City, La.; Randy Tarpley of Jonesville, La.; Charles W. Nelson of Pensacola, Fla.; Allen Boudreaux Jr. of Ama, La.; and Jorey A. Rivero of Bridge City, La. The survivor was identified as Steven Yeltin of Floresville, Texas.
A bird strike also preceded a Jan. 15 emergency that forced a North Carolina-bound US Airways jetliner to ditch into New York's Hudson River moments after taking off from LaGuardia Airport. The remains of Canada geese were found in both engines of the jet. All 155 crew members and passengers survived.
The New York accident focused attention on the problem of airplanes colliding with birds. The high speeds at which commercial airliners fly greatly magnifies the force of an impact, and the larger the bird, the greater the impact.