Narrative:
The aircraft was on final approach to Chicago O'Hare Airport when a structural failure of the number three flap track occurred. The aircraft sustained substantial damage to the left wing, left inboard flap assembly, left inboard spoilers and spoiler support beam. The pilot experienced significant uncommanded roll and yaw, but regained control of the aircraft and executed an uneventful landing.
The investigation has revealed a history of flap track cracking problems associated with stress corrosion and design inadequacy. A design change of the member was accomplished in 1971 by the manufacturer, but flap tracks of the earlier design were allowed to remain in service on 239 aircraft. The airworthiness directives and service bulletins applicable to this particular structural member are not adequate in methodology and periodicity to ensure crack detection, and do not require inspection for the cause of the crack-corrosion pits.
PROBABLE CAUSE: "Failure of the number three flap track due to stress corrosion cracking. factors contributing to this failure are insufficient design of the member and inadequate inspection and maintenance procedures to detect cracks before they propagate to a critical length."
Normal landing
| Status: | Accident investigation report completed and information captured |
| Date: | Monday 9 May 1988 |
| Time: | 16:35 |
| Type: |  Boeing 747-136 |
| Operator: | British Airways |
| Registration: | G-AWND |
| MSN: | 19764/107 |
| First flight: | 1971-01-20 (17 years 4 months) |
| Total airframe hrs: | 1868 |
| Engines: | 4 Pratt & Whitney JT9D-7A |
| Crew: | Fatalities: 0 / Occupants: 18 |
| Passengers: | Fatalities: 0 / Occupants: 286 |
| Total: | Fatalities: 0 / Occupants: 304 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | near Chicago-O'Hare International Airport, IL (ORD) ( United States of America)
|
| Phase: | Approach (APR) |
| Nature: | International Scheduled Passenger |
| Departure airport: | London-Heathrow Airport (LHR/EGLL), United Kingdom |
| Chicago-O'Hare International Airport, IL (ORD/KORD), United States of America |
The aircraft was on final approach to Chicago O'Hare Airport when a structural failure of the number three flap track occurred. The aircraft sustained substantial damage to the left wing, left inboard flap assembly, left inboard spoilers and spoiler support beam. The pilot experienced significant uncommanded roll and yaw, but regained control of the aircraft and executed an uneventful landing.
The investigation has revealed a history of flap track cracking problems associated with stress corrosion and design inadequacy. A design change of the member was accomplished in 1971 by the manufacturer, but flap tracks of the earlier design were allowed to remain in service on 239 aircraft. The airworthiness directives and service bulletins applicable to this particular structural member are not adequate in methodology and periodicity to ensure crack detection, and do not require inspection for the cause of the crack-corrosion pits.
Probable Cause:
PROBABLE CAUSE: "Failure of the number three flap track due to stress corrosion cracking. factors contributing to this failure are insufficient design of the member and inadequate inspection and maintenance procedures to detect cracks before they propagate to a critical length."
Classification:
Issue with flap(s)Normal landing
Sources:
» NTSBFollow-up / safety actions
NTSB issued 3 Safety Recommendations
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Photos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from London-Heathrow Airport to Chicago-O'Hare International Airport, IL as the crow flies is 6297 km (3936 miles).
Distance from London-Heathrow Airport to Chicago-O'Hare International Airport, IL as the crow flies is 6297 km (3936 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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