The National Transportation Safety Board recommended last night that the Federal Aviation Administration ground all Sikorsky S61 helicopters after one of them crashed and killed three people at Newark International Airport Wednesday night.
The recommendation, made late yesterday, would apply to about 1,000 Sikorsky helicopters, including the ones that President Carter flies from the White House of Andrews Air Force Baseand other close-in destinations, according to a safety board spokesman.
The White House helicopter is officially designated Marine One, and isthus subject to military standards, not those of the FAA. White House and Pentagon spokesmen said last night that the military uses a "different model" of the S61 than the one that went down in Newark.
However, a Sikorsky spokesman said that while there was a difference, "I really can't tell you whether it was in the tail rotor assembly," the key part in question.
The FAA, the Pentagon and Sikorsky all said they would move rapidly to take appropriate action when they receive the safety board report.
The helicopters should be grounded, the safety board said, "until a means of detecting potential tail rotor blade failures can be devised and implemented."
Investigators probing the crash at Newark Airport yesterday discovered that a 35-inch section of one of the five blades on the tail rotor of the S61L had separated in flight from the rest of the rotor.
"It appears that the resultant unbalance caused a massive failure in the tail rotor gear-box," the board said.
The piece of the blade was found about 1,000 feet from the site of the helicopter crash on the threshold of runway 22L at Newark. The rest of the tail rotor was discovered about 200 feet from the crash.
The helicopter flight was a regularly scheduled shuttle between New York City area airports by New York Airways, which suspended service yesterday.
The dead was identified as Mrs. Edward Stolars, 63 of Wallington N.J.; Cecilia Augusta, 75, of Newark, and Richard Dunbar, 56, of Rockford, Ill. In addition, 15 people were injured, four critically.
The helicopter had just taken off from Newark when the pilot radioed that "I'm having a control problem." He attempted to return to the airport, and got to its edge about 200 feet from the New Jrsey Turnpike when the helicopter went out of control and plummeted to the ground.
Investigators found a huge hole in the rear underside of the tail boom, apparently where parts of the gearbox had penetrated or where the piece of blade had struck.
The blade was flown to the safety board's Washington laboratory, where a metallurgical examination revealed a "fatigue crack through approximately 90 percent of the leading edge spar," the board said. That crack could not be detected through normal visual examinations.
Bob Carroll, a spokesman for Sikorsky, said the S-61 has been in service for more than 20 years. About 900 S-61s are in military use, and 130 more are used commercially for such purposes as ferrying crews to offshore oil wells.