Airworthiness Directives; Airbus Model A310 Series Airplanes and Model A300-600 Series Airplanes

This airworthiness directive (AD) supersedes two existing ADs. One AD applies to certain Airbus Model A310-200 and -300 series airplanes. That AD currently requires repetitive inspections for cracking of the flap transmission shafts, and replacement of the transmission shafts if necessary. That AD also provides an optional terminating action for the repetitive inspections. The other existing AD applies to all Airbus Model A300 B4-600, B4-600R, and F4-600R series airplanes, and Model C4-605R Variant F airplanes (collectively called A300-600 series airplanes); and Model A310-200 and -300 series airplanes. That AD currently requires a one-time inspection of the trimmable horizontal stabilizer actuator (THSA), corrective actions if necessary, and follow-on repetitive tasks. This new AD also requires revising the Airworthiness Limitations Section of the Instructions for Continued Airworthiness to incorporate new limitations and maintenance tasks for aging systems maintenance. This AD results from the manufacturer's determination that life limitations and maintenance tasks are necessary to ensure continued operational safety of the affected airplanes. We are issuing this AD to prevent reduced structural integrity of these airplanes due to the failure of system components.