The General Electric engine on the Airbus jetliner that crashed in New York City yesterday has a pattern of recent failures that prompted federal safety officials to warn of the possibility of a "catastrophic accident," government records show.
The failures of GE's widely used CF6 engines have not been blamed for any crashes. But they have forced emergency landings and caused fires after metal parts broke off and smashed through engine housings, according to two warning letters issued last year by the National Transportation Safety Board.
While NTSB investigators had reached no conclusions yesterday about the cause of the crash, they are likely to be reviewing the record of the GE engine along with other past safety issues involving the Airbus A300. Officials and outside experts agreed yesterday the crash was probably not the result of terrorism.
Rudy Kapustin, a former chief investigator for the NTSB, said the GE engine's documented problems are "troublesome and reason for concern." He noted that one of the engines visible in the wreckage on television yesterday appeared to have a gaping hole in its housing, though it was impossible to say whether the hole had been caused by engine parts or by an impact on the ground.
But he also called the CF6 engine "fairly reliable overall" and noted that as many as 6,000 are in service - including the engines on Air Force One, the presidential plane.
Any engine so common is likely to experience occasional failures and become the target of Federal Aviation Agency repair orders, called emergency airworthiness directives, said Kapustin, of Columbia, now a private consultant.
General Electric dispatched two engine experts to the crash scene last night to assist with the investigation, said Rick Kennedy, a spokesman for GE's aircraft engine division in Cincinnati.
In addition to the engines, investigators will be reviewing the safety record of the Airbus A300-600.
The Airbus A300 series, introduced in 1972, is one of the workhorses of contemporary aviation, a mid-sized jet used by some 94 airlines around the world. The A300 has not been particularly accident-prone, and five previous crashes were all blamed on bad weather or human error.
But the plane has drawn at least one safety warning. In 1998, the FAA ordered inspections of fuel pumps on the Airbus A300-600 after French inspectors found dangerous cracks on three planes. The emergency order said repairs were required to "prevent a possible ignition source in the center fuel tank."
The problem with the GE CF6 engines is a pattern of what aviation experts call "uncontained failures" - a structural breakup of the engine in which metal parts are expelled like shrapnel.
Kennedy, the GE spokesman, acknowledged the problems but said there have been "fewer than a dozen" such failures since the CF6 series was introduced in 1971. "You add it all up and you have the most reliable engine in the industry," he said.
Last year alone, however, the NTSB documented at least five instances in which the CF6 engine failed because of cracks, causing several near-crashes. The most troublesome part has been the 3 1/2 -foot-long titanium spools, which hold the engine's spinning blades in place.
Just moments before lifting off from Newark International Airport in April 2000, the 220 passengers of a Continental DC-10 were startled by a loud boom. The left engine had partially disintegrated. The pilots were forced to dump their fuel and maneuver the crippled plane back to the ground.
Investigators later counted 27 holes in the fuselage and wing, some as large as basketballs and all made by engine fragments, according to a January Wall Street Journal article about the engine's recent troubles.
In June 2000, a similar incident occurred to a Varig Airlines Boeing 767 in Sao Paulo, Brazil. Moments before the plane was to lift off, pilots aborted the takeoff. Four passengers were injured during the emergency evacuation.
Investigators later traced the problem to the failure of a titanium spool. "Such ruptures, if uncontained, could result in a catastrophic accident," NTSB investigators warned in their report.
In August 2000, the FAA ordered CF6 engines checked for cracks in the spools. GE says a new kind of spool installed since 1995 does not have the same problems, and it is encouraging airlines to replace the older models.
The month after FAA-ordered inspections, a US Airways Boeing 767 was undergoing a maintenance check at Philadelphia International Airport when one of the CF6 engines exploded. A 45-pound chunk ripped through a fuel tank and a wing, igniting a fire.
The metal projectile was never recovered, but investigators concluded it probably landed in the nearby Delaware River. In December, the NTSB issued a second warning, saying the Philadelphia incident raised "serious safety concerns."
"If it had occurred during flight rather than on the ground during maintenance, the airplane might not have been able to maintain safe flight," investigators wrote.
General Electric, in response to the NTSB letter, suggested airlines inspect the CF6 turbine disk, which was blamed for the Philadelphia explosion. The company says the inspections turned up no other faults.
But in May, an Airbus A300-600 bound from London to the Gambia experienced another CF6 engine failure that forced an emergency landing.
Investigators found two holes in the engine housing, one 12 inches wide and the other 3 inches wide, and concluded that a worn-out rotor blade inside the engine had broken off.