EASA AD US-2020-26-09
Wings - Center Wing Box Fastener Holes - Inspection
Summary
FAA Airworthiness Directive 2020-26-09 is a final rule addressing all Boeing 737-100, -200, -200C, -300, -400, and -500 series airplanes. It mandates inspections of the center wing box fastener holes for cracks using high frequency eddy current, ultrasonic, or detailed internal inspection methods. The directive aims to maintain structural integrity by detecting and repairing cracks in critical wing components.
What Changed
This new airworthiness directive introduces repetitive inspections of the center wing box fastener holes at station 663.75 rear spar on specified Boeing 737 models. It requires either external HFEC and ultrasonic inspections or internal detailed inspections, with repairs as necessary. The directive also clarifies that installation of Supplemental Type Certificate STC ST01219SE does not affect compliance requirements.
Why It Matters
This directive is critical for aviation professionals because cracks in the center wing box fastener holes can compromise the structural integrity of the airplane, potentially leading to failure of principal structural elements. Operators and maintenance teams must ensure timely inspections and repairs to prevent unsafe conditions and maintain airworthiness. Compliance helps avoid costly structural failures and ensures continued safe operation of affected Boeing 737 aircraft.
What To Do
Operators of affected Boeing 737-100 through -500 series airplanes must perform the required inspections within 120 days of January 27, 2021, or according to the compliance schedule in Boeing Alert Requirements Bulletin 737-57A1348 RB dated June 1, 2020. Inspections include repetitive external HFEC and ultrasonic or internal detailed inspections of the center wing box fastener holes. Any detected cracks must be repaired following approved procedures. No alternative method of compliance is needed for airplanes with STC ST01219SE installed.
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