Cabin Pressure Issue on Boeing 757

National Transportation Safety Board
Washington, DC 20594

The National Transportation Safety Board recommends that the Federal Aviation Administration:

Require Boeing to develop a method to protect the elevator power control unit input arm assembly on 737-300 through -500 series airplanes from foreign object debris. (A-11-7)

Once Boeing has developed a method to protect the elevator power control unit input arm assembly on 737-300 through -500 series airplanes from foreign object debris as requested in
Safety Recommendation A-11-7, require operators to modify their airplanes with this method of protection. (A-11-8)

Require Boeing to redesign the 737-300 through -500 series airplane elevator control system such that a single-point jam will not restrict the movement of the elevator control system and prevent continued safe flight and landing. (A-11-9)

Once the 737-300 through -500 series airplane elevator control system is redesigned as requested in Safety Recommendation A-11-9, require operators to implement the new design. (A-11-10)

Require Boeing to develop recovery strategies (for example, checklists, procedures, or memory items) for pilots of 737 airplanes that do not have a mechanical override feature for a jammed elevator in the event of a full control deflection of the elevator system and incorporate those strategies into pilot guidance. Within those recovery strategies, the consequences of removing all hydraulic power to the airplane as a response to any uncommanded control surface should be clarified. (A-11-11)