# NTSB ATL90IA060: Douglas DC-9-31, N8978E, Louisville, KY, January 31, 1990

- Type: NTSB incident investigation
- Classification: Incident · Minor injuries · Incident investigation · Final report
- Date: January 31, 1990, 14:31 local (19:31 UTC)
- Place: Louisville, KY
- Coordinates: 38.26025, -85.539436 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.2602&lon=-85.5394&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 2 minor, 71 uninjured
- Status: Completed, report December 30, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 8154
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL90IA060
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8154/pdf
- Page: https://openairdocs.org/ntsb/ATL90IA060

## 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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, landing - roll
  - landing gear,main gear strut scissors - disabled (cause)
  - inadequate quality control, production/design personnel (cause)
- Fire, landing - roll

## Analysis

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.

## Aircraft

- Registration: [N8978E](https://openairdocs.org/deregistered/N8978E-2010-07-20), registration cancelled 2010-07-20, S/N 47327, built 1968 (OpenAirDocs)
- Reported make and model: DOUGLAS DC-9-31
- Registry model: [Douglas DC-9-31](https://openairdocs.org/model/douglas-dc-9-31) (registry code 3022065) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-1](https://openairdocs.org/engine/pratt-whitney-jt8d-1) (registry code 52044, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 47327
- Airframe hours: 58041
- Engines: P&W JT8D-7B 14000 lbs thrust turbo jet
- Damage: Minor damage
- Fire: On-Ground
- Flight: Part 121
- Operator: Eastern Air Lines, Inc
- Registered owner: Unknown
- Last inspection: Continuous airworthiness, July 22, 1988
- Departed: MKE, MILWAUKEE, WI
- Destination: SDF
- Flight plan: IFR
- Airport: SDF, Standiford Field, runway 29, 7,249 × 150 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 9,000 total, 374 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 170° at 8 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 54 °F
- Altimeter: 30.00 inHg
- Observed at: SDF, 1 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19900131001729I](https://openairdocs.org/incident/19900131001729I), Jan 31, 1990: Doug DC931, Louisville, KY, Minor damage. Tower advised fire on left side on rollout. Evacuated. Torque link apex bolt sheared and gear assembly rotated.

## Other investigations on N8978E (2)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB ATL84LA235](https://openairdocs.org/ntsb/ATL84LA235), Jul 25, 1984: Douglas DC-9-31 (N8978E), Augusta, GA, no damage
- [NTSB IAD74AI035](https://openairdocs.org/ntsb/IAD74AI035), Dec 17, 1973: Douglas DC-9 (N8978E), Greensboro, NC, substantial damage

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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