# NTSB SEA94IA103: Mcdonnell Douglas MD-83, N931AS, Seattle, WA, April 18, 1994

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: April 17, 1994, 18:55 local (Apr 18, 1994, 01:55 UTC)
- Place: Seattle, WA
- Coordinates: 47.439029, -122.280685 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.4390&lon=-122.2807&mi=10
- Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 139 uninjured
- Status: Completed, report February 14, 1995
- Report: Approved by Office Director
- NTSB case key (mKey): 41827
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA94IA103
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41827/pdf
- Page: https://openairdocs.org/ntsb/SEA94IA103

## Probable cause

THE FATIGUE FRACTURE OF A MAIN GEAR WHEEL HUB.

## Sequence of events

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

- Airframe/component/system failure/malfunction, taxi - from landing
  - landing gear,wheel - fractured (cause)
- Fire, standing - engine(s) operating
  - fluid,hydraulic - burned

## Analysis

DURING THE LANDING/TAXI SEQUENCE, THE LEFT MAIN GEAR WHEEL HUB EXPERIENCED A FATIGUE FRACTURE. THE CRACKS WHICH LED TO THE FRACTURE ORIGINATED IN THE HUB GREASE DAM GROOVE. THE FRACTURING OF THE HUB DAMAGED OTHER BRAKE COMPENENTS, WHICH ALLOWED HYDRAULIC FLUID TO LEAK ONTO A HOT BRAKE PAD, WHERE IT WAS IGNITED.

## Factual narrative

On April 17, 1994, approximately 1855 Pacific daylight time (PDT), an Alaska Airlines McDonnell Douglas MD-83, N931AS, experienced a fire in the area of the left main gear while taxiing to the passenger loading gate at Seattle-Tacoma International Airport, Seattle, Washington. After stopping at the gate and requesting fire equipment, the captain ordered an emergency evacuation of the aircraft. There were no reported injuries to the 132 passengers, six crew members, or the single jump seat occupant. The aircraft, which departed San Francisco International Airport on an IFR flight plan at 1655 PDT, was operating in visual meteorological conditions at the time of the incident. This mishap did not involve the activation of an ELT.

According to tower personnel, smoke was seen coming from the area of the left main gear as the aircraft taxied to the gate. The tower notified the aircrew of the situation and, as the aircraft stopped at the gate, flames began coming from the same area, prompting the captain to initiate an emergency evacuation. Approximately half of the occupants evacuated through the normal jetway exit, while the other half exited using the tail cone slide.

The investigation has revealed that the left main gear wheel hub experienced a fatigue fracture which originated in the hub grease dam groove. Subsequent to the hub failure, hydraulic fluid, which was leaking from a damaged brake component, was ignited by a hot brake pad.

## Aircraft

- Registration: [N931AS](https://openairdocs.org/deregistered/N931AS-2009-11-19), registration cancelled 2009-11-19, S/N 49232, built 1985 (OpenAirDocs)
- Reported make and model: MCDONNELL DOUGLAS MD-83
- Registry model: [Mcdonnell Douglas DC-9-83(MD-83)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-83-md-83) (registry code 3022083) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-219](https://openairdocs.org/engine/pratt-whitney-jt8d-219) (registry code 51694, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 49232
- Airframe hours: 25773
- Engines: P&W JT8D-217A 20850 lbs thrust turbo fan
- Damage: Minor damage
- Fire: On-Ground
- Flight: Part 121
- Registered owner: Alaska Airlines
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, April 13, 1994, 41 hours before
- Departed: SFO, SAN FRANCISCO, CA
- Flight plan: IFR
- Airport: SEA, Seattle-Tacoma Int., runway 34R, 11,900 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 8,899 total, 3,764 in this make and model, 3,692 as pilot in command, 141 in the last 90 days, 52 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 340° at 3 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 63 °F, dew point 50 °F
- Altimeter: 30.00 inHg

## 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 19940417029239I](https://openairdocs.org/incident/19940417029239I), Apr 17, 1994: Doug DC982, Seattle, WA, Minor damage. After taxi into gate area tower advised smoke from landing gear. Evacuated wheel hub fractured. Replaced.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.