Crack in Engine Hub May Be Cause of Delta Jet Accident, Officials Say

The engine fan hub that broke apart as a jetliner was accelerating for takeoff had an inch-deep, preexisting crack that probably caused the accident that killed two passengers, federal officials said Monday.

Delta Air Lines replaced the fated jet’s left engine with a 1993 engine that itself was recycled using a hub that had been in use since 1987 on a third plane, National Transportation Safety Board officials said.

Although no final determination has been made, the crack--evidence of metal fatigue--appears to have been the cause of the hub’s failure, said Michael Marx, senior metallurgist for the NTSB.

“The crack is fairly substantial in size as it is now. It’s approximately one-inch deep,” Marx said at a news conference. “A crack of that size probably is sufficient to cause the separation of the disc.”

The crack started in a half-inch hole for one of the many bolts used to attach the 3-inch-wide hub to the rest of the engine. The titanium, 100-pound hub holds 34 blades to the center of the engine. When the hub broke in two during takeoff Saturday, those blades tore through the engine and the fuselage of the plane, killing a vacationing mother and her son.