Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all Airbus Model A330-200 and -300 series airplanes, and Model A340-200 and -300 series airplanes. The existing AD currently requires a repetitive inspection program on certain check valves in the hydraulic systems that includes, among other things, inspections for lock wire presence and integrity, traces of seepage or black deposits, proper torque, alignment of the check valve and manifold, installing new lock wire, and corrective actions if needed. Since we issued that AD, additional in-service reports of check valves loosening at lower flight cycle thresholds than previously reported have been received. This proposed AD would expand the applicability, reduce the compliance time, change torque values of the check valve tightening, and require a repetitive inspection program for certain check valves in the hydraulic systems on airplanes that have had a certain modification embodied during production or in-service. We are proposing this AD to detect and correct such check valve loosening, which could result in hydraulic leaks, possibly leading to the loss of all three hydraulic systems and consequent loss of control of the airplane.