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Bird Strike Was Likely Cause of Chopper Crash

THE WALL STREET JOURNAL

FEBRUARY 15, 2009, 5:49 P.M. ET

Federal investigators increasingly suspect that a collision with a bird led to the crash of a widely-used Sikorsky helicopter model last month that killed eight people in the Gulf of Mexico, according to industry officials and safety experts.

The Jan. 4 crash of the Sikorsky S-76C chopper, manufactured by a unit of United Technologies Corp., had initially stumped crash investigators, who had previously ruled out engine, transmission, electrical or hydraulic failures. The National Transportation Safety board, which is heading the probe, also said the chopper didn’t run out of fuel, hit some other aircraft or suffer a problem with its rotors. Now, investigators believe a bird strike destroyed the windshield and somehow resulted in nearly turning off the engines.

The initial difficulty in determining a cause raised widespread safety concerns. The Sikorsky chopper is a workhorse for many offshore-oil operations, emergency-medical transport firms and other commercial services world-wide, and there are currently 600 in operation. The chopper was being used by Royal Dutch Shell PLC’s U.S. unit, to transport workers to offshore facilities in the Gulf of Mexico. After the crash, Shell temporarily grounded its entire fleet of S-76C choppers, and instead used boats to transport most of those workers.

If a bird strike is ultimately determined to be the cause, the chopper crash would be the second instance over a period of less than two weeks in January that bird strikes caused high-profile aviation accidents in the U.S. A crippled US Airways jetliner ditched in New York City’s Hudson River in mid-January, after birds seriously damaged both of its engines, but there were no fatalities.

The NTSB had initially said it didn’t find any evidence of a bird strike in the helicopter crash. But investigators have since changed their focus, according to people familiar with the details. The NTSB has sent material taken from inside the cockpit to wildlife experts at the Smithsonian Institution to determine if they came from a bird, a board spokesman confirmed over the weekend. The spokesman also said the board is examining the center post of the windshield. That’s near the suspected point of impact with a bird.

Analysis of the sounds captured by the cockpit voice recorder reveal a sudden loud bang followed by an intense rush of wind, according to people familiar with the details. The board has said that one second later, power from both of the helicopter’s engines simultaneously dropped to almost nothing. Airspeed decreased slightly for the next 10 seconds, according to the board, while the helicopter descended and ultimately crashed.

One theory is that a remnant of the windshield, or some other force created by the impact, retarded the throttles and nearly shut off the engines.

Other signs point in the same direction. Sikorsky, the manufacturer of the helicopter, appears poised to issue a letter warning operators about the potential dangers of installing certain kinds of acrylic windshields. Such windshields are sometimes retrofitted in helicopters in order to save weight, but the crash has raised questions about the strength of some of them.

A spokesman for Sikorsky didn’t have any immediate comment. A spokesman for PHI Inc., Metairie, La., which operated the helicopter, has declined to take questions on the crash or the investigation.

The crash happened in clear weather while cruising at roughly 140 miles per hour at an altitude of 700 feet toward an offshore oil platform. At such a low altitude, the pilots would have little time to respond to such a near-shutdown of engines.

Write to Andy Pasztor at [email protected]

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