Airworthiness Directives; Airbus Model A300 B2 and B4 Series Airplanes; Model A300 B4-600, B4-600R, and F4-600R Series Airplanes, and Model A300 C4-605R Variant F Airplanes (Collectively Called A300-600 Series Airplanes); and Model A310-200 and -300 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Airbus airplane models, as specified above. This AD requires modifying the thermal insulation system of certain fuselage frames, and modifying the fuselage drainage system. This AD also requires revising the FAA-approved maintenance inspection program to include inspections for corrosion or cracking in the subject areas. This AD is prompted by reports of corrosion in the lower part of the pressure bulkhead at certain fuselage frames. We are issuing this AD to prevent accumulation of condensation in the insulation blankets of certain fuselage frames, which could cause corrosion that could result in reduced structural integrity of the fuselage and consequent rapid decompression of the airplane.