CHI02IA270

NTSB incident investigation · Fokker 100 · Minneapolis, MN · September 5, 2002

Incident · No injuriesIncident investigationFinal report
Date
September 5, 2002, 06:40 local (11:40 UTC)
Place
Minneapolis, MN
Injuries
33 uninjured
Damage
Minor damage
Phase of flight
Takeoff
Aircraft
N1473KFokker 100
Weather
Visual (VMC) · Dawn
Status
Completed · report September 30, 2003
Report
Approved by Office Director
Parties
American Airlines, FAA - Minneapolis FSDO
FAA report
20020905029409I
Case key
55802

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.

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Probable cause

The improper installation of the #2 main landing gear wheel, including the axle nut not being properly torqued and safetied, which resulted in the wheel separation during takeoff.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Airframe/component/system failure/malfunctionTakeoff
Landing gear,wheel - separationCause
Maintenance,service of aircraft/equipment - improperCompany maintenance personnelCause
Miscellaneous,bolt/nut/fastener/clamp/spring - undertorquedCause
Miscellaneous,bolt/nut/fastener/clamp/spring - not safetiedCause

Analysis

During takeoff the #2 wheel separated from the left main landing gear assembly. A company mechanic stated that during a walk-around inspection he noted the #1 and #2 main landing gear tires needed to be replaced. The #1 & #2 tires are on the left main landing gear assembly; with the #1 tire being outboard of the #2 tire. The mechanic reported, "We removed & replaced #2 main landing gear [tire], with nothing unusual during the tire change." The axle nut/spacer assembly was found with the wheel. The axle nut lock-bolts were found installed in the axle nut/spacer assembly with safety wire connecting the lock-bolts to the axle nut. The lock-bolts were not damaged. The interfacing threads between the axle nut/spacer assembly and the axle were not stripped and the treads were not worn. A demonstration of a wheel installation and a review of the installation procedures were performed at the request of the NTSB. In order for the lock-bolts to engage the axle keyslot, the axle nut/spacer assembly had to be properly torqued and wheel bearings seated.

Factual narrative

On September 5, 2002, at 0640 central daylight time, a Fokker 100, N1473K, operated by American Airlines, Fort Worth, Texas, sustained minor damage when the number two main landing gear wheel separated from the axle during takeoff from Minneapolis-St. Paul International Airport (MSP), Minneapolis, Minnesota. Visual meteorological conditions prevailed at the time of the incident. The scheduled passenger flight was operating under the provisions of 14 CFR Part 121 on an instrument flight rules (IFR) flight plan. The flightcrew and passengers reported no injuries. The flight made an uneventful landing at Chicago O'Hare International Airport (ORD) at 0735.

A company mechanic stated that during a walk-around inspection he noted the #1 and #2 main landing gear tires needed to be replaced. The #1 & #2 tires are on the left main landing gear assembly; with the #1 tire being outboard of the #2 tire. The mechanic reported, "We removed & replaced #2 main landing gear [tire], with nothing unusual during the tire change." The mechanic stated the #1 main landing gear tire was then replaced and "nothing unusual" was encountered during that tire change.

During takeoff the #2 wheel separated from the left main landing gear assembly and was found near the end of runway 12L.

The axle nut/spacer assembly was found with the wheel. The axle nut lock-bolts were found installed in the axle nut/spacer assembly with safety wire connecting the lock-bolts to the axle nut. The lock-bolts were not damaged. The interfacing threads between the axle nut/spacer assembly and the axle were not stripped and the treads were not worn.

A demonstration of a wheel installation and a review of the installation procedures were performed at the request of the NTSB. In order for the lock-bolts to engage the axle keyslot, the axle nut/spacer assembly had to be properly torqued and wheel bearings seated.

Aircraft

Registration
N1473K
Reported as
Fokker 100
Category
Airplane
Serial number
11515
Airframe hours
20,571.4
Engines
Rolls-Royce 850-15, 15,000 lbs thrust, turbo fanRolls-Royce 850-15, 15,000 lbs thrust, turbo fan
Damage
Minor damage
Flight
Part 121
Registered owner
American Airlines
Airworthiness certificate
Standard, Transport
Last inspection
Continuous airworthiness · September 5, 2002 · 28.83 hours before
Departed
MSP · Minneapolis, MN
Destination
ORD · Chicago, IL
Flight plan
IFR
Airport
MSP · Minneapolis-St. Paul Intl, runway 12L, 8,200 × 150 ft, asphalt

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew · 2

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
43
Injuries
None
Certificates
Commercial, Flight instructor, Airline transport
Airplane ratings
Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 1, Valid Medical--no waivers/lim.
Seat
Left
Flight hours
1,425 in this make and model
Role
Co-pilot
Age
39
Injuries
None
Certificates
Airline transport, Flight instructor
Airplane ratings
Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 1, Valid Medical--no waivers/lim.
Seat
Right
Flight hours
236 in this make and model

Weather

Conditions
Visual (VMC) · Dawn
Wind
150° at 7 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
63 °F, dew point 54 °F
Altimeter
30.10 inHg

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.