Airworthiness Directives; Learjet Model 35, 35A, 36, and 36A Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Learjet Model 35, 35A, 36, and 36A series airplanes, that requires revision of the Airplane Flight Manual (AFM) to add procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated. This amendment is intended to prevent incapacitation of the flightcrew due to lack of oxygen and consequent loss of control of the airplane due to absence of AFM procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated.