AD FAA-2007-27736

The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 777 airplanes. This AD requires a one-time inspection to determine the part number of the left and right air supply and cabin pressure controllers (ASCPCs) and installation of new ASCPC software if necessary. This AD results from a report of an ASCPC failure during flight. We are issuing this AD to prevent an ASCPC failure that could stop airflow into the airplane, inhibit the cabin altitude warning message, and cause an incorrect display of cabin altitude. These failures could result in depressurization of the airplane without warning.