EASA AD US-2021-17-06
Fuselage - Front Spar Shear Tie and Intercostal Lug Fitting - Inspection
Summary
FAA Airworthiness Directive 2021-17-06 is a final rule addressing all Boeing Model 747 series airplanes including 747-100 through 747SP variants. It mandates inspections of the front spar shear tie and intercostal lug fitting for cracks using detailed and high frequency eddy current methods. The directive aims to ensure structural integrity and prevent potential cargo restraint failures or fuel tank ruptures.
What Changed
This new airworthiness directive introduces repetitive detailed and surface HFEC inspections at specified locations on the front spar shear tie and intercostal lug fitting of Boeing 747 airplanes. It requires applicable on-condition repairs such as part replacement if cracks are found. The AD also clarifies compliance timelines and repair approval procedures.
Why It Matters
This AD is critical for aviation professionals as it addresses a structural safety concern that could compromise the airplane's load-bearing capability and cargo safety. Operators and maintenance teams must implement these inspections to prevent potential structural failures and ensure continued airworthiness. Compliance helps avoid costly unplanned repairs and enhances overall flight safety.
What To Do
Affected operators must perform repetitive detailed and HFEC inspections of the front spar shear tie and intercostal lug fitting at the specified buttock lines and stations as outlined in Boeing Alert Requirements Bulletin 747-53A2904 RB. Any detected cracks must be repaired or parts replaced following FAA-approved methods. Compliance with these actions is required by October 5, 2021.
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