NTSB Identification: FTW02IA061.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Scheduled 14 CFR (D.B.A. Air France)
Incident occurred Thursday, January 03, 2002 in Houston, TX
Probable Cause Approval Date: 01/24/2005
Aircraft: Boeing 747-228F, registration: F-GCBG
Injuries: 3 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

After a normal touchdown and rollout, the 747 cargo airplane exited the runway onto a high-speed taxiway. The captain, noticed that the airplane was "dragging," to the right. The need for additional power for taxi seemed too great, so the crew stopped taxi and applied the parking brake. On-site examination revealed the right outboard main landing gear trunnion was completely fractured and separated several inches inboard of the aft trunnion bearing. Further visual inspection of the fractured area showed evidence of corrosion and what appeared to be a pre-existing crack on the upper portion of the outer cylinder of the trunnion and a metallurgical examination showed evidence of stress corrosion cracking (SCC). The inspection criteria outlined in Airworthiness Directive (AD) repalc90-06-18 R1 required the operator to perform a visual inspection, or a visual plus eddy current inspection of the wing landing gear at the trunnion, for cracks and corrosion. The inspection criteria outlined in AD 2001-17-25 required the operator to perform a detailed visual inspection using a bore scope to find cracking and corrosion of the aft trunnion outer cylinders of the wing landing gear, within 180 days from October 3, 2001. According to the operator's records, the bore scope inspection had not been performed, as per the AD, it was not due until April 3, 2002. Historical review of Service Difficulty Reports (SDR's) revealed 19 occurrences of SCC associated with corrosion of the aft trunnion outer cylinder stressed areas. Due to these SDR data, the manufacturer issued ASB 747-32A2465 revision 1, which was mandated by a new FAA AD 2001-17-25. AD 2001-17-25 included a bore scope inspection of the affected area of the trunnion due to the fact that the propagation of SCC cracking was internal on the cylinder and not readily detected by visual or eddy current methods as per the original AD 90-06-18 R1.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

Stress corrosion cracking (SCC) of the aft trunnion outer cylinder. A factor was the inadequate inspection criteria of the Airworthiness Directive to detect pre-existing SCC.

Full narrative available

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