Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Model A310-200 and -300 series airplanes. This proposed AD would require repetitive inspections for cracking of the flap transmission shafts, and replacing the transmission shafts if necessary. This proposed AD also would provide an optional terminating action for the repetitive inspections. This proposed AD results from reports of longitudinal cracks due to stress corrosion in the transmission shafts between the power control unit (PCU) and the torque limiters of the flap transmission system. We are proposing this AD to detect and correct cracking of the flap transmission shaft, which could compromise shaft structural integrity and lead to a disabled flap transmission shaft and reduced controllability of the airplane.