Says Foreign Objects Can Damage Power Control Units

The NTSB has made a series of recommendations to the FAA concerning Boeing 737-300 through -500 series airplanes. The safety board says the FAA should 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. Once the method has been developed operators should be required to modify their airplanes with this method of protection.

Additionally, Boeing should be required to redesign the 737-300 through -500 series airplane elevator control system so that a single-point jam will not restrict the movement of the elevator control system and prevent continued safe flight and landing, and implementation of that design should be mandatory.

B737-500

Finally, the NSTB recommends that Boeing be required 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.

FMI: www.ntsb.gov