NTSB Safety Recommendation A-11-7 through -11

[NTSB Press Releases <ntsbpressreleases@xxxxxxxx>]

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                   NTSB SAFETY RECOMMENDATION
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National Transportation Safety Board
Washington, DC 20594

February 14, 2011

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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)




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http://www.ntsb.gov/recs/letters/2011/A-11-007-011.pdf

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The complete recommendation letter is available on the Web 
at the URL indicated above.

The letter is in the Portable Document Format (PDF) and can 
be read using the Acrobat Reader 5.0 or later from Adobe 
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An archive of recommendation letters is available at 
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Electronic versions of letters may or may not include 
enclosures; however, related publications, accident 
briefs, and aviation accident synopses may be found 
on the NTSB website.

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