Airworthiness Directive · Amendment 39-18168 · Air conditioning
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-400, 747-400D, 747-400F, 747-8F, and 747-8 series airplanes, certificated in any category, as identified in paragraphs (c)(1) and (c)(2) of this AD.
(1) Airplanes identified in Boeing Service Bulletin 747-21-2550, dated December 6, 2013.
(2) Airplanes identified in paragraph (h)(2) of this AD.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, 747-400D, 747-400F, 747-8F, and 747-8 series airplanes. This AD was prompted by reports of very high temperatures, near the floor in the aft lower lobe cargo compartment. This AD requires installing an additional zone temperature sensor (ZTS) assembly in the aft cargo compartment, and, for certain airplanes, installing tape and replacing the markers in the bulk cargo compartment. We are issuing this AD to prevent overheating of the aft lower lobe cargo compartment, where, if temperature sensitive cargo is present, the release of flammable vapors could result in a fire or explosion if exposed to an ignition source.
Within 12 months after the effective date of this AD, remove the existing markers and install tape and new markers in the bulk cargo compartment, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-21-2544, Revision 2, dated December 11, 2014; or using a method approved in accordance with the procedures specified in paragraph (j) of this AD, as applicable. Accomplishing the actions specified in paragraph (h) of this AD within 12 months after the effective date of this AD terminates the requirements of this paragraph.
Within 60 months after the effective date of this AD, install an additional zone temperature sensor assembly in the aft cargo compartment, as specified in paragraph (h)(1) or (h)(2) of this AD, as applicable. Doing this action within 12 months after the effective date of this AD terminates the requirements of paragraph (g) of this AD.
(1) For airplanes identified in Boeing Service Bulletin 747-21-2550, dated December 6, 2013: Do the actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-21-2550, dated December 6, 2013.
(2) For airplanes having variable numbers RC021 and RC573: Do the actions using a method approved in accordance with the procedures specified in paragraph (j) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
