Airworthiness Directives; Boeing Model 737-800 Series Airplanes

The FAA is superseding an existing airworthiness directive (AD) that applies to certain Boeing Model 737-800 series airplanes. The existing AD currently requires inspecting flight spoilers to determine spoiler position after every landing and after any rejected takeoff maneuver. For airplanes on which any flight spoiler is found in the up position with the speedbrake handle in the down position, the existing AD requires replacing the flight spoiler actuator with a flight spoiler actuator having a certain part number. The existing AD also requires an operational test of the speedbrake control system after any maintenance actions that operate the spoiler system, and replacement of the flight spoiler actuator if necessary. The existing AD also provides for optional terminating action for those requirements. This new AD requires the previously optional terminating action. This AD results from a report of seven flight spoiler actuator jams on Model 737-800 airplanes equipped for short field performance (SFP). The cause of the failure has been identified as interference within the actuator main control valve. We are issuing this AD to prevent operation with defective flight spoiler actuators, which could result in a flight spoiler actuator hardover, and could cause the flight spoiler surface to jam in the fully extended position. Two or more hardover failures of the flight spoiler surfaces in the up direction on the same wing, if undetected prior to takeoff, can cause significant roll and consequent loss of control of the airplane.