Abstract of Final Report
Recommendations
To the Federal Aviation Administration
1. Require Boeing to determine the critical fan blade impact location(s) on the CFM56-7B
engine fan case and redesign the fan cowl structure on all Boeing 737 next-generation
series airplanes to ensure the structural integrity of the fan cowl after a fan-blade-out event.
2. Once the actions requested in Safety Recommendation [1] are completed, require Boeing
to install the redesigned fan cowl structure on new-production 737 next-generation-series
airplanes.
3. Once the actions requested in Safety Recommendation [1] are completed, require operators
of Boeing 737 next-generation-series airplanes to retrofit their airplanes with the
redesigned fan cowl structure.
4. Expand the Title 14 Code of Federal Regulations Part 25 and 33 certification requirements
to mandate that airplane and engine manufacturers work collaboratively to (1) analyze all
critical fan blade impact locations for all engine operating conditions, the resulting fan
blade fragmentation, and the effects of the fan-blade-out-generated loads on the nacelle
structure and (2) develop a method to ensure that the analysis findings are fully accounted
for in the design of the nacelle structure and its components.
5. Develop and issue guidance on ways that air carriers can mitigate hazards to passengers
affected by an in-flight loss of seating capacity.