Superseded by FAA AD 2023-03-15
- Published
- Effective
- Deadline
- Replaces
- 2007-07-03
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Affected operators must perform repetitive detailed inspections of all TADD materials for damage starting by May 12, 2021, and carry out any necessary repairs or replacements. Installing new high temperature composite TADDs can extend inspection intervals to 16,000 flight hours. Requests for compliance time extensions can be submitted with supporting data for FAA approval.
Summary
FAA Airworthiness Directive 2021-07-09 is a final rule superseding AD 2007-07-03 and applies to certain Boeing 747 series airplanes including models 747-100, 747-200, 747-300, 747-400, 747SR, and 747SP. It addresses issues with hot air leaking from trim air diffuser ducts (TADDs), including failures of high temperature composite material TADDs, which can damage the center wing fuel tank and create a fire or explosion risk. The directive mandates repetitive inspections and corrective actions to ensure continued airworthiness.
What changed
This AD supersedes AD 2007-07-03 by expanding inspection requirements to include all TADD materials, not just original fiberglass fabric, due to reported failures of high temperature composite TADDs. It requires repetitive inspections for damage and applicable on-condition corrective actions. The AD also clarifies that installing new high temperature TADDs can extend inspection intervals to 16,000 flight hours.
Why it matters
This directive is critical for aviation professionals because it addresses a potential safety hazard involving fuel tank integrity and fire risk caused by hot air leakage from TADDs. Operators and maintenance teams must comply to prevent fuel leakage into ignition zones, which could lead to catastrophic events. The AD impacts maintenance scheduling and parts availability, requiring careful planning to meet inspection intervals without disrupting operations.
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New ADs and bulletins for Boeing 747, 747SR and 747SP, summarized like this page, every Monday.