Air Conditioning - Trim Air Diffuser Ducts - Inspection / Replacement
- Published
- Effective
- Deadline
- Replaces
- 2021-07-09
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 TADDs for damage and replace these ducts every 16,000 flight hours as specified in Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2. Installation of original or affected TADD parts is prohibited. Compliance with these actions is mandatory by April 14, 2023, the effective date of the directive.
Summary
Airworthiness Directive 2023-03-15 is a final rule issued by the Federal Aviation Administration addressing all Boeing Model 747 series airplanes including 747-100, 747-200, 747-300, 747-400, 747SR, and 747SP variants. This directive focuses on the inspection and replacement of trim air diffuser ducts (TADDs) to prevent damage that could lead to fuel leakage and potential fire or explosion hazards. It supersedes previous requirements and updates inspection and replacement protocols for these critical air conditioning components.
What changed
This directive supersedes AD 2021-07-09 by revising compliance times for repetitive inspections of TADDs and removing structural inspections of the center fuel tanks. It introduces mandatory repetitive replacement of TADDs and prohibits installation of affected parts. Additionally, certain Boeing 747 Large Cargo Freighter airplanes are removed from applicability, and the directive references updated Boeing service bulletins for compliance.
Why it matters
This directive is crucial for aviation professionals as it addresses a significant safety risk involving potential hot air leakage from deteriorated TADD materials that could damage fuel tank barriers and lead to fire or explosion. Operators and maintenance teams must ensure compliance to maintain airworthiness and prevent catastrophic failures. The updated inspection and replacement requirements help mitigate risks associated with aging or damaged TADDs on Boeing 747 aircraft.
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