Airworthiness Directives; Lockheed Model 188A and 188C Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Lockheed Model 188A and 188C series airplanes, that requires a revision of the Airplane Flight Manual (AFM) to add procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated. The actions specified by this AD are intended to prevent incapacitation of the flightcrew as a result of 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.