Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes; Model 767-200, -300, -300F, and -400ER series airplanes; and Model 777-200, -200LR, -300, and -300ER series airplanes. This AD was prompted by operator or in-service reports of burned Boeing Material Specification (BMS) 8-39 urethane foam, and a report from the airplane manufacturer indicating that airplanes were assembled, throughout various areas of the airplane (including flight deck and cargo compartments), with seals made of BMS 8-39 urethane foam, a material with fire-retardant properties that deteriorate with age. This AD requires replacing certain seals made of BMS 8-39 urethane foam. We are issuing this AD to prevent the failure of urethane seals to maintain sufficient Halon concentrations in the cargo compartments to extinguish or contain fire or smoke, and to prevent penetration of fire or smoke in areas of the airplane that are difficult to access for fire and smoke detection or suppression.