AD FAA-2012-0149

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes. This AD was prompted by reports of fatigue cracks in the lap joints, which initiated at scribe lines that were made during production when maskant was removed from the affected skin panels during the chemical milling process. This AD requires repetitive external phased-array ultrasonic inspections to detect cracks of the affected fuselage skin lap splices in Sections 41, 43, and 44, as applicable, and repair if necessary. We are issuing this AD to detect and correct such fatigue cracking, which could grow large and cause sudden decompression and the inability to sustain limit flight and pressure loads.