ASN Aircraft accident Boeing 747-422 N174UA Los Angeles International Airport, CA (LAX)
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Status:Accident investigation report completed and information captured
Date:Monday 27 August 1990
Type:Silhouette image of generic B744 model; specific model in this crash may look slightly different
Boeing 747-422
Operator:United Airlines
Registration: N174UA
MSN: 24381/762
First flight: 1990-01-05 (8 months)
Total airframe hrs:2952
Engines: 4 Pratt & Whitney PW4056
Crew:Fatalities: 0 / Occupants: 20
Passengers:Fatalities: 0 / Occupants: 323
Total:Fatalities: 0 / Occupants: 343
Aircraft damage: Minor
Aircraft fate: Repaired
Location:Los Angeles International Airport, CA (LAX) (   United States of America)
Phase: Landing (LDG)
Nature:International Scheduled Passenger
Departure airport:Sydney-Kingsford Smith International Airport, NSW (SYD/YSSY), Australia
Destination airport:Los Angeles International Airport, CA (LAX/KLAX), United States of America
The crew noted that the nose and main body gear indicated up and locked after normal gear extension. The crew used the alternate gear extension procedure, which was unsuccessful. The aircraft landed on runway 25R with the nose and main body gear retracted when the flight reached the minimum fuel state. Examination of the aircraft revealed that the selector valve for the affected gear was in the up and locked position, and the bolt which connects the valve arm to the cockpit control cable system was missing. The bolt for the wing gear selector valve arm was found partially backed out; the nut and cotter pin were missing. The aircraft was delivered to United in January of 1990 and had 2,952 flight hours and 402 cycles. Detailed review of the maintenance records proved that United had not performed any maintenance on the landing gear system. A second alternate gear extension procedure involving de-energizing the hydraulic system for the affected gear is not published in the crew manuals, taught during initial training, nor available on any checklist.

Probable Cause:

PROBABLE CAUSE: "The failure of the manufacturer to ensure that the landing gear selector valves and their associated drum link assemblies were properly installed prior to delivery of the aircraft. A factor in the accident was the lack of information available to the crew concerning the secondary alternate gear extension procedure."

Accident investigation:

Investigating agency: NTSB
Status: Investigation completed
Duration: 2 years and 4 months
Accident number: LAX90IA305
Download report: Summary report

Forced landing on runway

» Aviation Week & Space Technology 3.9.90 (p.205)


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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 Sydney-Kingsford Smith International Airport, NSW to Los Angeles International Airport, CA as the crow flies is 12026 km (7516 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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