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Updated report out on Southwest WN-1380

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  • Updated report out on Southwest WN-1380

    CNN has reported that "Investigators of a fatal accident on a Southwest Airlines plane last year recommend that Boeing retrofit the [engine cowlings] of nearly 7,000 jets to prevent a repeat of the accident."

    The NTSB report concludes this:

    Originally posted by WN1380 NTSB Report
    5. Portions of the fan cowl departed the airplane because (1) the impact of the separated fan blade with the fan case imparted significant loads into the fan cowl through the radial restraint fitting and (2) the associated stresses in the fan cowl structure exceeded the residual strength of the fan cowl, causing its failure.

    7. This accident demonstrated the susceptibility of the fan cowl installed on Boeing 737 next-generation-series airplanes to a fan-blade-out impact location near the radial restraint fitting and the effects of such an impact on the structural integrity of the fan cowl.
    I'm not sure that a practical redesign capable of withstanding such forces is possible, but if it is, there is no associated AD requiring Boeing to redesign it.

  • #2
    It seems the redesign objective can be met:

    Originally posted by BBC
    NTSB chair Robert Sumwalt said the refit of the fan cowl structure could be expensive but was necessary to improve safety in the event of a fan blade issue.

    "These recommendations show the way toward greater safety even when a fan blade out event occurs," said NTSB chair Robert Sumwalt.
    Originally posted by Aerotime
    “This accident demonstrates that a fan blade can fail and release differently than that observed during engine certification testing and accounted for in airframe structural analyses,” said NTSB Chairman Robert Sumwalt in the accident report.

    [Boeing] also said it is working on a design enhancement “that would fully address the safety recommendation from the NTSB. Once approved by the FAA, that design change will be implemented in the existing NG fleet over the longer term.”
    Boeing also stated that fan blade inspections are adequate protection until the change can be made.