National Transportation Safety Board
Washington, DC 20594
February 23, 2012
The National Transportation Safety Board makes the following recommendations to the Federal Aviation Administration:
Modify the design and test requirements for the attachment points of passenger service units to account for the higher localized loading that results from the relative motion of the attachment structure. (A-12-1)
Require that the installation design for overhead bins and passenger service units (PSU) manufactured by Boeing and installed in Boeing 737NG series airplanes be modified so that the PSUs remain attached to the bins or are captured in a safe manner during survivable accidents. (A-12-2)
Review the designs of manufacturers other than Boeing for overhead bins and passenger service units (PSU) to identify designs with deficiencies similar to those identified in Boeing’s design, and require those manufacturers, as necessary, to eliminate the potential for PSUs to separate from their attachments during survivable accidents. (A-12-3)
Develop test criteria and performance measures for negative-g strap assemblies to better evaluate their real-world loading capability during accident sequences. (A-12-4)
Once test criteria and performance measures are established as recommended in Safety Recommendation A-12-4, amend 14 Code of Federal Regulations Part 25, as appropriate, to include the newly developed test criteria and performance measures for negative-g strap assemblies. (A-12-5)
Require that negative-g strap attachment brackets manufactured by Ipeco be retrofitted with stronger brackets. (A-12-6)
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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)
