AD FAA-2014-0342

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.