Airworthiness Directives; Airbus Model A330 and A340 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Airbus Model A330 and A340 series airplanes, that requires a one-time inspection to determine the manufacturer's name, part number, and date code of certain circuit breakers; and replacement of any suspect circuit breaker with a new improved circuit breaker. The actions specified by this AD are intended to ensure that proper circuit breakers are installed for the fire extinguishing system or part of the supplemental oxygen supply. A defective circuit breaker, if not corrected, could trip without the cockpit indication light illuminating. If the flightcrew is unaware of this situation while operating the airplane, this latent failure in combination with other failures could present an immediate hazard to the airplane. This action is intended to address the identified unsafe condition.