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Aviation safety reports, made easier to study

NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.

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January 31, 1990 · Douglas DC-9-31 · N8978E

Louisville, KY

Overview

Report Status
Probable Cause
Event Type
Incident
Date
January 31, 1990
Injury Outcomes
2 injuries (2 minor injuries), 71 uninjured
Location
Louisville, KY
Aircraft
Douglas DC-9-31
Tail Number
N8978E
Operator
Eastern Air Lines
Injuries
Minor
Aircraft Damage
Minor
NTSB Number
ATL90IA060

AFTER LANDING THE FLIGHT CREW NOTED A VIBRATION. LEFT MAIN GEAR TORQUE LINK APEX BOLT WAS FOUND TO HAVE VIBRATED OUT OF THE TORQUE LINK WHICH ALLOWED MAIN GEAR TRUCK TO ROTATE 360 DEGREES DURING LANDING ROLL. THE NUT HAD STRIPPED OFF OF THE BOLT. LABORATORY EXAMINATION REVEALED THAT THE TORQUE LINK ATTACHING PINS HAD EXCESSIVE PLAY. NEW & OLD APEX BOLTS WERE MEASURED. THEY FAILED TO PASS THE MOST STRINGENT QUALITY CONTROL CHECK FOR CORRECT THREAD SIZE. THE SAFETY BOARD BELIEVES THAT THE NUT STRIPPED OFF WHEN THE LOOSE TORQUE LINKS ALLOWED EXCESSIVE VIBRATION. THE UNDERSIZE APEX BOLT THREADS ALLOWED THE NUT TO SHEAR AWAY THE BOLT PIN DESIGNED TO RETAIN THE NUT.

NTSB Probable Cause

THE DISABLING OF THE MAIN LANDING GEAR TORQUE LINK WHICH ALLOWED THE TRUCK TO ROTATE FREELY. THE TORQUE LINK WAS DISABLED WHEN EXCESSIVE VIBRATION WAS GENERATED BY EXCESSIVE PLAY OF THE TORQUE LINK PINS IN THEIR BUSHINGS.

Full Narrative

AFTER LANDING THE FLIGHT CREW NOTED A VIBRATION. LEFT MAIN GEAR TORQUE LINK APEX BOLT WAS FOUND TO HAVE VIBRATED OUT OF THE TORQUE LINK WHICH ALLOWED MAIN GEAR TRUCK TO ROTATE 360 DEGREES DURING LANDING ROLL. THE NUT HAD STRIPPED OFF OF THE BOLT. LABORATORY EXAMINATION REVEALED THAT THE TORQUE LINK ATTACHING PINS HAD EXCESSIVE PLAY. NEW & OLD APEX BOLTS WERE MEASURED. THEY FAILED TO PASS THE MOST STRINGENT QUALITY CONTROL CHECK FOR CORRECT THREAD SIZE. THE SAFETY BOARD BELIEVES THAT THE NUT STRIPPED OFF WHEN THE LOOSE TORQUE LINKS ALLOWED EXCESSIVE VIBRATION. THE UNDERSIZE APEX BOLT THREADS ALLOWED THE NUT TO SHEAR AWAY THE BOLT PIN DESIGNED TO RETAIN THE NUT.

Flight

Event TypeIncident
Event Time13:31 CST
Nearest AirportStandiford Field (0nm N)
Runway29
Runway Length7249 ft
Runway Width150 ft
Flight Plan FiledIFR
Aircraft FireGrd
Aircraft ExplosionNo

Aircraft

AircraftDouglas DC-9-31
Tail NumberN8978E
Aircraft CategoryAir
DamageMinor
OperatorEastern Air Lines
Operating RulePart 121
Engines2
Engine TypeTurbojet
Engine DetailsP&W · JT8D-7B · Turbojet · 14000
Seats100

People & Injuries

Injury Summary2 injuries (2 minor injuries), 71 uninjured
Fatal0
Serious0
Minor2
Uninjured71
Total73
Crew 1Age 47 · First Class

Conditions

ConditionsVMC
LightDaylight
Wind170° @ 8 kt
Visibility15 sm
CeilingNone
Temperature / Dew Point54 / 0 C
Altimeter30.00 inHg
Observation Time19:50
Weather SourceWFAC

Appendix: Source Data