Airworthiness Directive · Amendment 39-21637 · Equipment/furnishings
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-400, 747-400D, and 747-400F series airplanes, certificated in any category, as identified in Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020.
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, 747-400D, and 747-400F series airplanes. This AD was prompted by reports of burned Boeing Material Specification (BMS) 8-39 urethane foam found in certain locations on the airplane; investigation revealed that the fire-retardant properties degrade with age. This AD requires inspecting the insulation blankets in certain areas of the forward cargo compartment for exposed BMS 8-39 urethane foam, not encapsulated by a protective fire resistant barrier, and for seal integrity, and replacing the BMS 8-39 urethane foam and seal if necessary. 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 Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020.
Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Special Attention Service Bulletin 747-25-3725, dated October 27, 2020, which is referred to in Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020.
Where Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020, uses the phrase “after the Original Issue date of Requirements Bulletin 747-25-3725 RB,” this AD requires using “the effective date of this AD.”
