AD FAA-2013-0863

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-8F and 747-8 series airplanes. This AD requires a detailed inspection of the power control actuator (PCA) installation to determine if a bushing is installed, a general visual inspection between the horizontal stabilizer rear spar and the elevator front spar and between certain stabilizer stations for defects and damage, and corrective actions if necessary. This AD was prompted by a report of unusual noise coming from the left inboard elevator during a functional check of the ram air turbine system, and a determination that a bushing was not installed. We are issuing this AD to detect and correct non-installation of bushings. If the bushings are not present, the stiffness of the load path will be decreased, which will cause wear of adjacent parts and increased freeplay of the elevator surfaces. Freeplay that exceeds acceptable limits could result in divergent flutter for certain maneuvers, which could lead to loss of controllability of the airplane.