Airworthiness Directive 2021-26-10
one-timeAirworthiness Directives; The Boeing Company Airplanes
What this AD requires
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. This AD was prompted by reports of burned Boeing Material Specification (BMS) 8-39 urethane foam, and a report from the airplane manufacturer that airplanes were assembled with seals throughout various areas of the airplane (including flight deck and cargo compartments) made of BMS 8-39 urethane foam, a material with fire- retardant properties that deteriorate with age. This AD requires replacing the system tube/wire seals made of BMS 8-39 urethane foam in certain areas of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.
Which aircraft AD 2021-26-10 applies to
Applies to airplanes identified as Group 11 Configuration 2; Group 13 and 14 Configuration 4; and Group 16, 17, and 19 Configuration 5, in Boeing Special Attention Service Bulletin 747-25-3381, Revision 3, dated February 19, 2021.
Whether AD 2021-26-10 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.