Federal Register #2026-13129

FAA Proposed Airworthiness Directive for Boeing 747-400 Series – Water Leak Inspections

The Federal Aviation Administration (FAA), under the Department of Transportation, is proposing a new airworthiness directive (AD) for Boeing 747-400 series airplanes to address safety concerns related to water leaks. - Government Buyer: - Federal Aviation Administration (FAA) - Airworthiness Products Section, Operational Safety Branch - OEM Highlighted: - The Boeing Company - Products/Services Requested: - Repetitive inspections of potable and waste water lines, galley compartments, and lavatory sinks for leaks and clogs - On-condition corrective actions to resolve any detected issues, including rendering water/waste systems or components inoperable if necessary - Procedures referenced in Boeing Message TBCTBC25669401B - Quantities: - 4 U.S.-registered Boeing 747-400 series airplanes affected - Unique/Notable Requirements: - Inspections must occur within 1,000 flight hours of directive effective date and recur at intervals not exceeding 1,000 flight hours - Immediate corrective actions required before further flight if issues are found - Compliance with Boeing's Water Leak Check Work Instructions - Interim action pending a future modification - No specific part numbers or procurement of new products; this is a regulatory compliance requirement for ongoing maintenance and safety.

Description

The FAA proposes a new airworthiness directive (AD) for certain Boeing 747-400 series airplanes due to reports of potable water leaking into the electrical equipment bay cooling air inlet. The AD requires repetitive inspections of potential water sources, including potable and waste water lines, for leaks and clogs, and applicable on-condition actions to address the unsafe condition. The directive aims to prevent water leaks that could impact the function of essential electronics and line replaceable units, potentially resulting in loss of continued safe flight and landing. Comments on the proposed rule are invited until August 14, 2026.

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