Airworthiness Directives; Airbus Airplanes

We are superseding Airworthiness Directive (AD) 98-18-02 for certain Airbus Model A300 B4-600, B4-600R, and F4-600R series airplanes, and Model C4-605R variant F airplanes (collectively called A300-600 series airplanes). AD 98-18-02 required inspections to detect cracks in the center spar sealing angles adjacent to the pylon rear attachment and in the adjacent butt strap and skin panel, and correction of discrepancies. This new AD continues to require inspections for cracks. This new AD also requires a modification by cold expansion of the center spar sealing angles, replacement of both sealing angles and cold expansion of the attachment holes if necessary, and post-repair repetitive inspections and corrective actions if necessary. This AD was prompted by reports of cracking in the vertical web of the center spar sealing angles of the wing, and subsequent analyses that showed that the inspection threshold and interval specified in AD 98-18-02 must be reduced to allow timely detection of cracks on the sealing angles of the center spar, adjacent to rib 8. We are issuing this AD to prevent crack formation in the sealing angles, which could rupture the sealing angle and lead to subsequent crack formation in the bottom skin of the wing, and result in reduced structural integrity of the center spar section of the wing.