Most of the bodies of the people who were sitting in the back of China Airlines (CAL) Flight CI-611 were found naked, a telling indicator of the tremendous stripping forces of rapid decompression when the B747-200 came apart over the Taiwan Strait on May 25, 2002
Hopefully, the last moments for the 225 passengers and crew were blessedly brief. The 23-year old plane came apart from metal fatigue, the possible result of a repair made 22 years before. As in the expression for iron that "rust never sleeps," corrosion worked its way into the aluminum, the way shipworms once chewed their way through and weakened the wooden hulls of sailing ships.
The crash is likely to spur an increase in maintenance oversight, especially for older airplanes, and particularly of repair doublers, or the external patches applied to structure damaged in service. Such patching is commonly employed throughout the industry. In fact, the presence of more than 30 such patches scattered throughout the accident airplane reflects the extent of the practice. The accident findings suggest that hidden damage under doublers can be deadly. Since the cracking and corrosion under a doubler cannot be seen by visual inspection, periodic nondestructive inspection may become necessary. Already, the National Transportation Safety Board (NTSB) has said as much, adding that the actions taken by the Federal Aviation Administration (FAA) to inspect tail strike repairs on B747s need to be expanded to cover all transport category aircraft (see ASW, April 21).
Read Full Article »
