Airworthiness Directives; Airbus Airplanes

We are superseding Airworthiness Directive (AD) 2013-13-04, for certain Airbus Model A318, A319, A320, and A321 series airplanes. AD 2013-13-04 required installing a power interruption protection circuit for the landing gear control interface unit (LGCIU). This new AD requires a new modification of any previously modified LGCIU. This new AD also requires revising the maintenance or inspection program to reduce a certain functional check interval. This new AD also adds airplanes to the applicability. This AD was prompted by a determination that additional work is necessary to adequately address the identified unsafe condition. We are issuing this AD to prevent untimely unlocking and/or retraction of the nose landing gear (NLG), which, while on the ground, could result in injury to ground personnel and damage to the airplane.