Airworthiness Directives; The Boeing Company Model 747 Airplanes and Model 767 Airplanes Equipped With General Electric Model CF6-80C2 or CF6-80A Series Engines

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires revising the airplane flight manual (AFM) to advise the flightcrew to use certain procedures during descent in certain icing conditions. This AD was prompted by reports of several in-flight engine flameouts, including multiple dual engine flameout events and one total power loss event, in ice-crystal icing conditions. We are issuing this AD to ensure that the flightcrew has the proper procedures to follow in certain icing conditions. These certain icing conditions could cause a multiple engine flameout during flight with the potential inability to restart the engines, and consequent forced landing of the airplane.