Airworthiness Directives; Airbus Airplanes

We propose to supersede Airworthiness Directive (AD) 2016-01- 11, which applies to certain Airbus Model A320-211, -212, and -231 airplanes. AD 2016-01-11 requires repetitive inspections for cracking of the radius of the front spar vertical stringers and the horizontal floor beam on frame 36, repetitive inspections for cracking of the fastener holes of the front spar vertical stringers on frame 36, and repair if necessary. Since we issued AD 2016-01-11, we received a report that, during a center fuselage certification full scale fatigue test, cracks were found on the front vertical stringer at a certain frame. This proposed AD would add new thresholds and intervals for the repetitive inspections; would require, for certain airplanes, a modification of the center wing box area; and would expand the applicability. We are proposing this AD to address the unsafe condition on these products.