China Airlines Flight 611
On February 7, 1980 the tail of the plane struck the runway while landing at Hong Kong airport. The plane was then ferried back to Taipei. A temporary repair was done on February 8, 1980, while a permanent repair was done from May 23 to 26, 1980. Later it was discovered the repair was not done to Boeing repair standards. It was also discovered that from 1997 a total of 29 corrosion inspections were not completed. When the repair patch was recovered from the crash site, there was evidence that deep scratches had been polished out, thinning the metal. Several fatigue cracks were found in the scratches. Crash investigators estimate a crack of about 71 inches may have caused the plane to break up.