Event Details

Title:Loss of main wheel, Boeing 737-347, December 24, 1999
Micro summary:During takeoff, a wheel separated from the main landing gear of this Boeing 737-347.
Event Time:1999-12-24 at 1349 MST
File Name:1999-12-24-US.pdf
Publishing Agency:National Transportation Safety Board (NTSB)
Publishing Country:USA
Report number:DEN00IA032
Site of event:Salt Lake City, UT
Departure:Salt Lake City International Airport, Salt Lake City, Utah, USA
Destination:Detroit Metropolitan Wayne County Airport, Romulus, Michigan, USA
Airplane Type(s):Boeing 737-347
Flight Phase:Takeoff
Operator(s):Delta Air Lines
Type of flight:Revenue
Serious Injuries:0
Other Injuries:0
Executive Summary:

NTSB short summary:

Improper assembly of the wheel during build up in the operator's maintenance facilities.

NTSB synopsis:

During takeoff roll on a scheduled domestic passenger flight, the right main landing gear inboard wheel separated from the aircraft. The aircraft returned to the point of departure and landed without further incident. Examination of the landing gear revealed that the wrong wheel bearing had been installed when the wheel assembly was 'built up' at the operator's facility.

NTSB factual narrative text:

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.
Learning Keywords:Operations - Maintenance
Systems - Landing Gear
Systems - Landing Gear - Tires
Systems - Landing Gear - Wheel Separation
Close match:Loss of nosewheel on Ryanair Boeing 737-204 at Dublin Airport, Ireland, on December 3, 2000
Loss of nose wheel on takeoff, Airbus A320-214, G-BXKD
Hard landing and wheel separation, Douglas DC-8-63F, July 18, 1998
Wheel separation on takeoff, Boeing 737-222, April 7, 1995
Loss of main wheel, Douglas DC-9-51, October 14, 1999
Wheel separation, Boeing 727-2K5, N900PG, March 10, 1997


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