National Transportation Safety Board

摘要

On November 27, 2005, the rudder, part number (P/N) A55471500 (premodification 8827), on an Airbus A300-600 airplane operated by Federal Express, N717FE, was damaged during routine maintenance. To assess the extent of the damage, the lower rudder rib was removed and the rudder was examined. In addition to the damage that occurred during maintenance, the examination found a substantial area of disbonding between the inner skin of the composite rudder surface and the honeycomb core. A tap test inspection determined that a disbond of approximately 838 mm (33 inches) by 355 mm (14 inches), or 0.3 square meter (3 square feet), existed. Further examination of the disbonded area revealed traces of hydraulic fluid. Hydraulic fluid contamination between the honeycomb core and the fiberglass composite skin can lead to progressive disbonding, which compromises the strength of the rudder. Further tests on the damaged rudder revealed that a rapid propagation of the disbonding damage could occur during flight.