Airworthiness Directives; Airbus Airplanes

We are adopting a new airworthiness directive (AD) for all Airbus Model A340-600 series airplanes. This AD requires modifying the fire extinguishing system from a three-bottles solution with 4 flow metering compact unit into a two-bottles solution with 2 flow metering systems equipped with upgraded water absorbing filter elements. This AD was prompted by reports of partial blockage of a certain water absorbing filter element. We are issuing this AD to prevent partial blockage of a certain water absorbing filter element, which could lead to reduction of the halon outflow, which leads to incapacity to maintain fire extinguishing agent concentration. Combined with fire, this condition could result in an uncontrolled fire in the affected compartment.