A crack that caused an engine to shatter on a Delta Air Lines flight last year, killing two people, was first detected in 1989 but appeared insignificant, a representative of the engine's maker told investigators Wednesday.
The National Transportation Safety Board opened a hearing to examine the inspections of engine parts.
On July 6, 1996, the left engine fan hub ruptured as the plane rolled down the runway for takeoff on a flight from Pensacola to Atlanta. The engine shredded, sending metal fragments into the passenger cabin that killed Anita Saxton, 39, of Scottville, Mich., and her 12-year-old son, Nolan.
NTSB and Delta metallurgists who examined the wreckage agreed the hub had a 1-inch-long crack inside of one of 24 bolt holes used to fasten the hub to the engine. Inspection records show that in 1989, a small crack was found on one of the bolt holes. A drill used to make the bolt hole had caused the crack, which eventually grew bigger.
The abnormality is rare but was not seen as significant at the time, said Douglas J. Scussell of engine manufacturer Pratt & Whitney.
Scussell told the panel that Hartford, Conn.-based Pratt & Whitney has been revising its inspection process to focus more on the bolt holes.