Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 787-8 airplanes. This proposed AD was prompted by a report that a captain's seat moved uncommanded during a landing rollout due to a failure in the seat horizontal actuator. This proposed AD would require repetitive tests of the captain and first officer seat assemblies for proper operation, and corrective action if necessary. This proposed AD would also require installing new captain and first officer seat assemblies, which would terminate the repetitive tests. We are proposing this AD to prevent a seat actuator clutch failure, which could result in a loss of seat locking and uncommanded motion of the captain's or first officer's seat; uncommanded seat movement could result in reduced controllability of the airplane.