AD FAA-2011-0725

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 767-200, -300, and -300F series airplanes. This AD was prompted by reports of loss of avionics cooling due to an unserviceable relay installed on a panel as part of the cabin air conditioning and temperature control system (CACTCS). This AD requires doing certain wiring changes, installing a new relay and necessary wiring in the CACTCS, and performing an operational test of the cooling pack system. We are issuing this AD to prevent loss of electrical equipment bay cooling and the overheating of flight deck instruments, which would result in the eventual loss of primary flight displays, an unusually high pilot workload, and depressurization of the cabin.