NEW YORK (CBSNewYork/AP) -- Investigators examining the wreckage of a helicopter that crashed in the East River and killed a passenger have found no evidence that the engine failed, as they spent several hours Thursday questioning the pilot of the aircraft.
The investigators found no metal particles on a magnetic monitoring device inside the Linden, New Jersey-based helicopter's engine that could have indicated damage, said National Transportation Safety Board member Mark Rosekind.
PHOTO GALLERY: East River Helicopter Crash
That and the lack of a rupture in the engine case were "a good indication there was no engine failure at the time of the accident" he said.
Sonia Marra, a 40-year-old British woman who lived in Australia and was visiting the city with her family to celebrate her 40th birthday, died in Tuesday's crash.
Marra's body was pulled from the water by police divers 90 minutes after the Bell 206 helicopter crashed Tuesday afternoon after taking off from a Manhattan riverside heliport near the United Nations headquarters.
Three other passengers were injured, including Helen Tamaki, who was reported to be in critical condition with possible damage to her lungs and brain. All were friends of the pilot, investigators have said.
Thursday's examination of the wreckage by NTSB investigators focused largely on a mechanical chip detector, Rosekind said at a news conference in a riverside parking lot not far from the crash site. The monitoring device, commonly found in helicopters, plugs into the engine to attract particles of metal that are chipped off and can indicate internal damage.
Rosekind said, however, that in spite of so far finding no mechanical cause for the crash, the NTSB was not yet ruling anything out. He said they had also found no obstruction in the oil system or contaminants in the oil itself. The fuel was being analyzed.
He said the NTSB was also continuing to search for a missing portion of the helicopter's rotor blade.
Meanwhile, Rosekind said investigators were talking to the pilot, Paul Dudley, who managed the Linden airport, where many New York City helicopters are based.
Rosekind said investigators had initially spoken to Dudley after the crash, but were talking to him a second time Thursday for at least three hours "to understand what happened in the accident" by going over his flight review, preflight planning and safety briefing to passengers before taking off.
They would also be asking the pilot about the takeoff sequences and any actions or responses to what happened.
The NTSB expected to release a preliminary report about the crash by Oct. 12.
"We're still, if you think about it, really at the beginning of collecting the factual information to be able to analyze it," Rosekind said.
The NTSB planned to remove the engine from the helicopter's frame Friday and ship it to a facility to be torn down so that the pieces can be examined.
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