Wings - Upper Wing Skin, Strut Lower Spar Fitting, Clevis Lugs at End of the Diagonal Brace and Lower Link Fitting - Repetitive Inspections
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AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators of affected Boeing 747 models must conduct the specified ultrasonic and detailed inspections at the intervals outlined in Boeing Alert Requirements Bulletin 747-57A2363 RB, starting no later than January 14, 2021. Any detected cracking must be repaired before further flight using FAA-approved methods. Requests for alternative methods of compliance should be submitted to the FAA Seattle ACO Branch as specified.
Summary
The Federal Aviation Administration (FAA) Airworthiness Directive 2020-21-16 addresses all Boeing Model 747 series airplanes, including 747-100 through 747SP variants. This directive mandates repetitive inspections of the upper wing skin at engine nacelle attachment points, as well as inspections of the strut lower spar fitting, diagonal brace clevis lugs, and lower link fitting to detect cracking. The goal is to ensure continued structural integrity of the engine strut and wing box assembly.
What changed
This new airworthiness directive introduces mandatory repetitive ultrasonic and detailed inspections targeting potential undetected cracking in critical wing and engine strut components on Boeing 747 series airplanes. It requires operators to follow Boeing Alert Requirements Bulletin 747-57A2363 RB dated December 23, 2019, and to perform on-condition repairs as necessary. The directive also clarifies compliance timelines and repair approval procedures.
Why it matters
For aviation professionals, this directive is crucial to prevent structural failures that could lead to engine strut separation from the wing, posing significant safety risks. Maintenance and compliance teams must integrate these inspections into their routine programs to detect and address cracks early. Operators must ensure adherence to the inspection intervals to maintain airworthiness and regulatory compliance.
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