Airworthiness Directives; the Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200LR, -300, -300ER, and 777F series airplanes. This AD was prompted by reports of dual pitch rate sensor (PRS) failures causing the primary flight computers to transition from primary mode to secondary mode, resulting in autopilot disconnects. This AD requires an inspection to determine the PRS part number, and replacement if necessary. We are issuing this AD to prevent a dual PRS failure that could cause an automatic disengagement of the autopilot and autoland, which may prevent continued safe flight and landing if disengagement occurs at low altitude and the flight crew is unable to safely assume control and execute a go-around or manual landing.