Airworthiness Directives; Boeing Model 747-100, -200, -300, and 747SP Series Airplanes

This amendment adopts a new airworthiness directive (AD); applicable to certain Boeing Model 747-100, -200, -300, and 747SP series airplanes; that requires certain inspections to find missing and alloy-steel taperlock fasteners (bolts) in the diagonal brace underwing fittings; and corrective actions, if necessary. For airplanes with missing or alloy-steel fasteners, this AD also mandates replacement of certain fasteners with new fasteners, which constitutes terminating action for the repetitive inspections. This action is necessary to prevent loss of the underwing fitting load path due to missing or damaged alloy-steel taperlock fasteners, which could result in separation of the engine and strut from the airplane. This action is intended to address the identified unsafe condition.