AD FAA-2012-0497

We are superseding an existing airworthiness directive (AD) for certain The Boeing Company Model 777-200, -200LR, -300, and -300ER series airplanes. That AD currently requires inspecting for scribe lines in the skin along lap joints, butt joints, certain external doublers, and the large cargo door hinges, and doing related investigative and corrective actions if necessary. This new AD adds an inspection for scribe lines where external decals have been applied or removed across lap joints, large cargo door hinges, and external doublers, and related investigative and corrective actions if necessary. This AD was prompted by a determination that scribe lines could occur where external decals are installed or removed across lap joints, large cargo door hinges, or external doublers. We are issuing this AD to detect and correct scribe lines, which can develop into fatigue cracks in the skin. Undetected fatigue cracks can grow and cause sudden decompression of the airplane.