Airworthiness Directives; Dassault Model Mystere-Falcon 50, Mystere-Falcon 900, and Falcon 900EX Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Dassault Model Mystere-Falcon 50, Mystere-Falcon 900, and Falcon 900EX series airplanes, that requires revising the Emergency Procedures and Abnormal Procedures sections of the airplane flight manual to advise the flightcrew to immediately don oxygen masks in the event of significant pressurization or oxygen level changes. The actions specified by this AD are intended to prevent incapacitation of the flightcrew due to lack of oxygen, which could result in their inability to continue to control the airplane. This action is intended to address the identified unsafe condition.