Airworthiness Directives; The Boeing Company Model 777-200, -200LR, -300, and -300ER Series Airplanes

We propose to adopt a new airworthiness directive (AD) for certain Model 777-200, -200LR, -300, and -300ER series airplanes. This proposed AD would require repetitive detailed inspections for disbonding and tearing and measurements for wear of the internal diameter (ID) of the Karon-lined bushings of the bulkhead support jackscrew fitting and of the jackscrew fitting of the horizontal stabilizer; repetitive installations of the horizontal stabilizer trim actuator (HSTA); and if necessary, replacement of the bushings with new bushings and all applicable related investigative and corrective actions. This proposed AD results from a report indicating that a Karon-lined bushing with the liner broken into five pieces was found during a scheduled inspection of the HSTA components; the broken liner had worn and disbonded from the bushing. We are proposing this AD to detect and correct discrepancies of the HSTA attachment locations, which could result in reduced structural integrity of the horizontal stabilizer and consequent loss of controllability of the airplane.