WASHINGTON– The Federal Aviation Administration (FAA) has issued a new Airworthiness Directive (AD), effective from April 23, 2025. This applies to all Boeing 777-200, -200LR, -300, -300ER, and 777F aircraft models.
This regulatory action follows the discovery of a 5-inch crack on the right wing’s upper skin at a specific wing station. Under the directive, operators must conduct recurring inspections. These inspections are to check for cracks in the upper wing skin around certain fasteners. Then, perform required remedial actions when issues are found. The FAA has implemented this AD to mitigate safety risks associated with this condition across the affected fleet.
Boeing 777 Wing Crack
The FAA is implementing an AD, effective from April 23, 2025, for all Boeing 777-200, -200LR, -300, –300ER, and 777F aircraft. The regulatory process began with a November 2023 Notice of Proposed Rulemaking (NPRM).
The initial action was prompted by the discovery of a 5-inch crack on the right wing’s upper skin at wing station 460.
The directive evolved with a September 2024 supplemental notice of proposed rulemaking (SNPRM). This was based on Boeing’s reports of two additional cracking incidents at fastener locations 6 and 7, where cracks spread in the spanwise direction. These cracks were only discovered during repairs of adjacent fasteners.
Significantly, the FAA changed the required inspection method from the originally proposed ultrasonic (UT) inspections to open-hole high-frequency eddy current (HFEC) inspections. HFEC proved more effective at detecting these particular cracks. The directive mandates recurring inspections of the upper wing skin around certain fasteners and appropriate remedial actions to address this safety concern.
Discussion of Final AD
The FAA received comments from five commenters: Boeing, All Nippon Airways (NH), Air France (AF), FedEx (FX), American Airlines (AA), and United Airlines (UA).
Request for Time Extension
American Airlines (AA) requested a compliance time extension for previously inspected aeroplanes. This can allow them to fly up to 4,700 flight cycles or 10,300 flight hours from the time of the inspection.
United (UA) requested an additional grace period to conduct the fastener 6 and 7 open-hole HFEC inspection on aeroplanes. UT inspection was already conducted before the issuance of the final rule.
The FAA disagreed with the request. It stated that a grace period extension or allowing credit for accomplishing the UT inspection may not adequately maintain an acceptable level of safety due to factors such as aeroplane age, utilization, and inspection history. Operators may request a compliance time extension through alternative methods of compliance (AMOC) if necessary.
Air France (AF) has requested clarification from the FAA on the fastener inspection compliance time. This is for aeroplanes that have already completed inspection instructions by Boeing Alert Requirements Bulletin 777-57A0125 RB, dated July 25, 2023.
The FAA agreed to clarify the inspection compliance time. It also includes a grace period of 12 months or 4,300 flight hours after the effective date of the proposed AD. For aeroplanes inspected without the open-hole HFEC inspection, the FAA may consider compliance time extensions through AMOCs. However, sufficient supporting data should be submitted to show an acceptable level of safety. This comes after Air France had already inspected some Group 4 aeroplanes without finding any issues after the UT inspection.
Request to allow Open Hole HFEC Inspections
All Nippon Airways (NH) has requested the FAA to accept the procedure of performing open-hole HFEC inspections instead of UT inspections for affected fasteners. Boeing Information Notice instructs operators to perform this.
The FAA disagrees, as it has already identified the open-hole HFEC procedure and additional approval would not be required.
Request To Limit Inspection
FedEx (FX) has requested to revise paragraphs of the proposed AD to only cover Model 777F (Group 6) aeroplanes with over 40,000 total flight hours or 6,500 total flight cycles. The company argues that the inspection intervals in the Boeing Alert Requirements Bulletin 777-57A0125 RB and the added requirements are not in the public interest.
FedEx also notes that no cracks were found on aeroplanes with less than 48,000 total flight hours and for those with over 40,000 hours. There are low rates of crack findings.
The FAA acknowledges that removal of interference fit fasteners may require oversizing the fastener hole. However, no delays in inspections are allowed. The FAA will consider alternate inspection intervals for compliance time extensions. Substantial data must be submitted to show an acceptable level of safety is maintained with alternate inspection intervals.
Boeing Alert Requirements Bulletin 777-57A0125 RB, issued July 25, 2023, was examined by the FAA. This document outlines methods for routine checks for upper wing skin cracking, which is typical of several fasteners, as well as relevant on-condition measures. On-condition actions include repair.
Bottom Line
The FAA concluded that adopting this AD as suggested is necessary for air safety. FAA is issuing this AD to remedy the dangerous outcomes of these products.
This AD is accepted as suggested in the SNPRM, except for a few minor editorial adjustments. No operator’s financial burden will be increased by any of the modifications.
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