N305WA

On December 24, 1999, at 1349 mountain standard time, a Boeing 737-347, N305WA, operated by Delta Airlines as flight 1079 from Salt Lake City, Utah, to Detroit, Michigan, sustained minor damage when the landing gear right main inboard wheel assembly separated from the airplane during takeoff from Salt Lake City. There were no injuries to the 6 crew members and 127 passengers and the aircraft returned and landed at Salt Lake City, without incident, at 1630. The flight was operating under Title 14 CFR Part 121 as a scheduled domestic passenger flight and visual meteorological conditions prevailed. An IFR flight plan was filed.

When the wheel separated from the aircraft it struck and damaged runway lighting. (See attached photographs.)

Examination of the aircraft, following the event, revealed that a Boeing 757 main wheel bearing had been installed when the wheel was built up by Delta maintenance in Atlanta, Georgia.

The difference between the two wheel bearings is the inner diameter of the bore. The correct bearing (part number 596) has a diameter of 3.375 inches and the incorrect bearing (part number 594) has a diameter of 3.750 inches.

Boeing Commercial Airplane Group records search provided information that five cases of incorrect bearing installation have been reported to Boeing: Two cases in 1990, one in 1997, and two in 1999.