Airworthiness Directives; Airbus Airplanes

We propose to adopt a new airworthiness directive (AD) for certain A330-200 Freighter, -200 and -300 series airplanes; and Airbus Model A340-200, -300, -500, and -600 series airplanes. This proposed AD was prompted by reports of certain hydraulic reservoirs (HRs) becoming depressurized due to air leakage from the HR pressure relief valve (PRV). This proposed AD would require repetitive inspections of the hydraulic fluid levels and nitrogen gas pressure in the HR for each hydraulic circuit, and if necessary, adjustment of the fluid level(s) and nitrogen pressure in affected HRs. We are proposing this AD to detect and correct air leakage from the HR PRV, which could lead to the loss of one or more hydraulic systems, with the possible result of loss of control of the airplane.