Douglas DC-9-31 N8978E

Summary

On 31 January 1990 at about 19:31 local time, a Douglas DC-9-31 registered N8978E, operated by Eastern Air Lines, Inc, was involved in an incident near Louisville, Kentucky, United States. 73 people were on board and 2 had minor injuries. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

31 January 1990 at 19:31

Classification

Incident

Location

Louisville, Kentucky, United States

Nearest airport

Standiford Field (SDF)

Coordinates

38.2603, -85.5394

Aircraft

Douglas DC-9-31

Registration

N8978E

Category

Airplane

Engines

2

Operator

Eastern Air Lines, Inc

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Milwaukee → Unknown

Aircraft damage

Minor

Weather

VMC

Light

Day

NTSB number

ATL90IA060

2 people had minor injuries.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.