Airworthiness Directives; Construcciones Aeronauticas, S.A. (CASA) Model CN-235 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain CASA Model CN-235 series airplanes, that requires disabling the brake control valve of the propeller. This amendment also requires that, prior to restoring propeller brake operation, the propeller brake control unit be replaced with a certain new propeller brake control unit. This amendment is prompted by reports of uncommanded activation of the propeller brake system on in-service airplanes during flight, due to the existing design of the brake control valve. The actions specified by this AD are intended to prevent in-flight uncommanded activation of the propeller brake system, which could result in in-flight shutdown of the engine.