Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 757 airplanes. This AD was prompted by a report of extensive corrosion of the ballscrew of the drive mechanism of the horizontal stabilizer trim actuator. This AD requires repetitive detailed inspections for discrepancies of the horizontal stabilizer ballscrew assembly; repetitive lubrication of the horizontal stabilizer trim control system; repetitive measurements for discrepancies of the ballscrew to ballnut freeplay; and corrective actions, if necessary. We are issuing this AD to prevent undetected failure of the primary and secondary load paths for the ballscrew in the horizontal stabilizer, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane.