FAA Adopts Fatigue Limits For Transport Aircraft

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A new rule adopted by the FAA this week stops short of requiring "life limits" for transport-category aircraft, but in practice that may be the result. The rule requires manufacturers to set a "limit of validity," the number of flight cycles or hours that an airplane can operate before it must be subjected to additional inspections for fatigue damage. Once those limits are determined, the FAA must approve any extension of the limit. Operators may choose to retire older airplanes rather than submit to more time-consuming and costly approvals and maintenance schedules, according to the Dallas Morning News. Deadlines to set the limits vary from 18 months to five years away. "We've addressed the problem of aging aircraft with numerous targeted regulations and 100 airworthiness directives over the years," said FAA Administrator Randy Babbitt. "This rule is a comprehensive solution to ensure the structural safety of today's airliners and the airplanes of tomorrow."

An airplane's metallic structures are stressed and can develop cracks when they experience repeated loads such as the pressurization and depressurization that happens on every flight, the FAA said. While airlines regularly inspect aircraft for cracks exceeding a certain size, widespread fatigue damage is characterized by the development of numerous tiny cracks, none of which would have raised concerns individually but which together run the risk of joining up and impairing the structural integrity of the aircraft. The new regulation applies to airliners with a takeoff weight of 75,000 pounds and heavier, as well as to all transport designs certificated in the future. The affected models total 4,198 U.S.-registered airplanes.