Jet-Engine Crack Is Suspected As Accident Cause -- Probers Study 1- Inch Flaw In Recycled Part

PENSACOLA, Fla. - An inch-deep crack in a recycled part probably caused an engine on a Delta jet to blow apart as it accelerated for takeoff, spraying shards of metal that killed two passengers, federal investigators said.

Although no final determination has been made, the crack in an engine-fan hub - evidence of metal fatigue - appears to be the reason the rapidly spinning part broke in two, said Michael Marx, senior metallurgist for the National Transportation Safety Board.

A Delta metallurgist came to the same conclusion, said George Black, an NTSB member.

The hub had been used on another engine and then installed seven months ago during the repair of an oil leak on the engine involved in the accident, officials said.

"I don't know that I'd call it used, but it was a part of an engine that was sold to Delta Air Lines, I believe, in 1987," Black said. "But it is not uncommon, I am told, to switch major components on engines when there's maintenance work done."

Delta said today that the Pratt & Whitney JT8D-219 engine is built so parts can be swapped out continually from other engines.

"They take it apart and do inspections to see how it's wearing and then it's reassembled as a modular unit," said spokesman Todd Clay. "It's not like you pull a part out and you throw it away."

Delta officials said they would wait for the NTSB to complete its investigation before making any changes in the company's operation.

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 100-pound titanium hub holds 34 blades to the center of the engine.

When the hub broke in two during takeoff Saturday from Pensacola Regional Airport, those blades tore apart the engine and part of the plane's fuselage, hitting the heads of a vacationing woman and her son, two of 142 passengers aboard.

An autopsy found Anita Saxton, 39, and her son Nolan, 12, of Scottville, Mich., were killed instantly. Two of Saxton's children and five other passengers were injured.

Part of the broken hub landed 2,400 feet away after flying over a road.

The parts were sent to the NTSB's laboratory in Washington, D.C. The agency also will examine Delta's maintenance records.

"Looking at their inspection program and looking at the nature of this defect will allow us to see whether they should have caught it," Black said.

The NTSB, Delta and engine maker Pratt & Whitney said the hub break was extremely unusual.

NTSB officials said no other engine of the type used on the MD-88 has ever experienced a broken fan hub but that the same thing happened to an outer ring on the fan of a General Electric engine in 1989, contributing to a United DC-10 crash in Sioux City, Iowa, that killed 112.

A preliminary review of the Delta cockpit voice recorder also indicated that before takeoff, the crew had sighted an oil leak on a part known as the bullet, just in front of the engine fan.

"It was dismissed, and there was no further discussion of it," Black said.

He said he was uncertain whether the leak was related to the engine failure.

Clay, the Delta spokesman, said the airline was not convinced the replacement hub or the oil leak observed by the crew before takeoff necessarily contributed to the accident.

"No one knows when it cracked," Clay said. "The crack could have come a second before it came apart, (or) the crack could have been there."