(CNN) -- A 2009 helicopter crash in which eight people died was due to a bird striking the chopper's windshield, the National Transportation Safety Board said Wednesday.
"Contributing to the accident, the board said, were the lack of [Federal Aviation Administration] regulations and guidance requiring helicopter windshields to be resistant to bird strikes," among other factors, the NTSB said in a news release.
On January 4, 2009, a dual-engine Sikorsky S-76C helicopter crashed into marshy terrain near Morgan City, Louisiana, about seven minutes after takeoff from Amelie, Louisiana. The copter was on a charter flight to a Gulf of Mexico oil rig. Both pilots were killed, along with six of the seven passengers, according to the NTSB.
Heard on the helicopter's cockpit voice recorder was a "loud bang, followed by sounds consistent with rushing wind and a power reduction on both engines," according to the statement. "The aircraft crashed several seconds later."
Feathers and other debris, identified as belonging to a red-tailed hawk, were collected from the helicopter's canopy and windshield, the NTSB said.
Investigators believe the bird's impact jarred the fire extinguisher T-handles loose and moved them aft, which pushed both engine control levers into the flight idle position, reducing fuel to both engines, the statement said. "The pilots were probably disoriented from the broken windshield and rushing air and were unable to react in time to maintain control of the helicopter."
The helicopter was registered to and operated by PHI Inc., the board said. The helicopter initially was equipped with laminated glass windshields that complied with European bird-strike resistance standards, but PHI had replaced them with lighter-weight acrylic windshields without bird-strike resistance.
The crash occurred just days before pilot Chesley Sullenberger and co-pilot Jeffrey Skiles landed a US Airways flight in the Hudson River at New York City after a bird strike to the engines. Only a few minor injuries were reported. The January 15 landing made heroes of Sullenberger and his crew.