The National Transportation Safety Board called yesterday for federal specialists to review the design of the fasteners in the covering of a jet engine that failed and crippled a Northwest Airlines DC10 last January, forcing an emergency landing at Dulles International Airport.
None of the 10 crew members or 43 passengers was injured in the incident, which began when a 29-inch fan blade snapped in a Pratt & Whitney JT9D turbofan engine mounted under the right wing. The blade had been weakened by a burn from an unknown source.
The broken blade damaged or destroyed some bolts. The engine's nose cowl, or cover, and fan case then flew off. Debris damaged the wing's leading edge and was sucked into the aircraft's rear engine, mounted in the tail. The rear engine sustained substantial damage but continued functioning, according to the board.
The board concluded that if the plane had been flying at a different altitude and speed or with its flaps and landing gear in different positions, a "catastrophic accident" might have occurred, board spokesman Ira J. Furman said yesterday. The board is an independent body with no enforcement powers.
Jim Lynch, a spokesman for the Connecticut-based Pratt & Whitney, said he believed that not all of the parts mentioned by the board were manufactured by Pratt & Whitney but that the company would withhold comment pending study of the board's statement.
In the United States and abroad, about 390 Boeing 747s and 38 DC10s are powered by versions of the JT9D, Lynch said.