Airworthiness Directive · Amendment 39-21486 · Air conditioning
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2023-03-15. Comply with the one in force.
This AD 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, certificated in any category.
The FAA is superseding Airworthiness Directive (AD) 2007-07- 03, which applied to certain 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 2007-07-03 required repetitive tests to detect hot air leaking from the trim air diffuser ducts or sidewall riser duct assemblies (collectively referred to as TADDs), related investigative actions, and corrective actions if necessary. AD 2007-07-03 also provided an optional terminating action for the repetitive tests. This AD requires repetitive inspections of all TADD material for damage and applicable on-condition actions. This AD was prompted by reports that high temperature composite material TADDs installed as specified in AD 2007-07-03 have also failed. 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, dated February 18, 2020, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 747-21A2577 RB, dated February 18, 2020.
Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 747-21A2577, dated February 18, 2020, which is referred to in Boeing Alert Requirements Bulletin 747-21A2577 RB, dated February 18, 2020.
(1) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, dated February 18, 2020, uses the phrase “the original issue 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, dated February 18, 2020, 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 (j) of this AD.
