Airworthiness Directive · Amendment 39-22340 · Air conditioning
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category, as identified in Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023.
The FAA is superseding Airworthiness Directive (AD) 2021-07- 09, which applies to all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. AD 2021-07-09 required repetitively inspecting all trim air diffuser ducts or sidewall riser duct assemblies (collectively referred to as TADDs) for damage, including repetitive structural inspections of the center fuel tanks for damage, and performing applicable on-condition actions. Since the FAA issued AD 2021-07-09, the agency has determined that the existing requirements do not adequately address the unsafe condition. This AD continues to require repetitive inspections of the TADDs for damage, with revised compliance times, and repair if applicable. This AD also requires repetitive replacement of the TADDs and removes the structural inspections of the center fuel tanks. This AD also prohibits the installation of affected parts. This AD removes certain airplanes from the applicability. The FAA is issuing this AD to address the unsafe condition on these products.
Except as specified by paragraph (h) of this AD: At the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023.
Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 747-21A2577, Revision 2, dated February 10, 2023, which is referred to in Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023.
(1) Where the Compliance Time column of the tables in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023, uses the phrase “the Revision 1 date of Requirements Bulletin 747-21A2577 RB,” this AD requires using “the effective date of this AD.”
(2) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 2, dated February 10, 2023, specifies contacting Boeing for repair instructions: This AD requires doing the repair before further flight using a method approved in accordance with the procedures specified in paragraph (k) of this AD.
