AD FAA-2012-1104

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200LR and -300ER series airplanes. This AD requires reviewing the airplane's maintenance records for each rudder power control unit (PCU) to identify the condition of its related reaction link assembly, and replacing the rudder PCU and its related reaction link assembly if necessary. This AD was prompted by a report of an abnormal airframe vibration in the aft fuselage during flight. We are issuing this AD to prevent excessive freeplay in the rudder control surface, which could cause rudder vibration, and result in structural damage severe enough to prevent continued safe flight and landing.