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Accident description
Last updated: 22 October 2017
Status:Final
Date:Saturday 22 August 1987
Time:13:12
Type:Silhouette image of generic B762 model; specific model in this crash may look slightly different
Boeing 767-231ER
Operator:Trans World Airlines - TWA
Registration: N609TW
C/n / msn: 22572/65
First flight: 1983
Total airframe hrs:12336
Engines: 2 Pratt & Whitney JT9D-7R4D
Crew:Fatalities: 0 / Occupants: 9
Passengers:Fatalities: 0 / Occupants: 172
Total:Fatalities: 0 / Occupants: 181
Airplane damage: Substantial
Airplane fate: Repaired
Location:Belleville-Scott AFB, IL (BLV) (   United States of America)
Phase: Landing (LDG)
Nature:Domestic Scheduled Passenger
Departure airport:San Francisco International Airport, CA (SFO/KSFO), United States of America
Destination airport:Saint Louis-Lambert International Airport, MO (STL/KSTL), United States of America
Flightnumber:TW756
Narrative:
While Boeing 767 N609TW was parked overnight at the gate at San Francisco (SFO), mechanics found an unserviceable brake and tire, requested a work order, and some time between 03:00 and 05:00 they removed and replaced the No.3 brake and wheel assembly on the right main landing gear. Both mechanics were long time employees of TWA but neither had ever changed the wheel/brake assembly on a Boeing 767. During the installation of the wheel/brake assemblies, the mechanics installed the pin through the end of the brake rod, but only partially into the brake torque arm. The bolt used to secure the pin in the torque arm and prevent it from migrating outward probably was not inserted through the hole in the pin.
TWA Flight 756 departed at 10:47. When the landing gear was retracted after takeoff, the No. 3 brake rod connector pin would have been head end downward. During the en route phase of the flight, the pin dropped out of the brake torque housing allowing the brake rod to move horizontally until coming to rest on the landing gear door pad, preventing the landing gear from extending before landing .
On the approach to runway 30L at Saint Louis-Lambert Airport (STL) and just before reaching the outer marker, the landing ear handle was lowered. Afterward, EICAS displayed "Gear Disagree, Gear Doors," and an aural gear unsafe warning sounded . The captain broke off the approach, departed the traffic pattern, and recycled the landing gear in accordance with the "Gear Disagree " procedure. However, the right main landing gear continued to show an unsafe condition. Alternate gear extension procedures were also without success. The captain of flight 756 then decided to land at Scott Air Force Base because of a more favorable runway wind component and because of the availability of on-base medical facilities and heavy crash/fire/rescue (CFR) equipment.
The aircraft landed with the right main landing gear fully retracted . The airplane came to rest in a nose-high, right-wing-low attitude with the right engine supporting the weight of the right wing.

Probable Cause:

PROBABLE CAUSE: "The improper installation of the No.3 right main landing gear wheel/brake assembly and the inadequate inspection of the maintenance."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 year and 8 months
Accident number: CHI87NA194
Download report: Summary report


Follow-up / safety actions

NTSB issued 3 Safety Recommendations

Show all AD's and Safety Recommendations

Photos

photo of Boeing 767-231ER N609TW
photo of Boeing 767-231ER N609TW
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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 San Francisco International Airport, CA to Saint Louis-Lambert International Airport, MO as the crow flies is 2768 km (1730 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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