Issued December 21, 2021, the Federal Aviation Administration Airworthiness Directive 2021-24-22 applies to all Pilatus Porter PC-6 models and is effective January 25, 2022. This AD replaces AD 2021-06-16 issued September 17, 2021. The AD describes the potential unsafe condition as “detachment or partial detachment of the elevator or rudder in flight.” The FAA is issuing this AD to prevent failure of the elevator or rudder attachment. The unsafe condition, if not addressed, could result in loss of control of the airplane. The AD divides the affected aircraft into two groups: Group 1 airplanes have not been modified in accordance with Pilatus PC-6 Service Bulletin (SB) No. 55-005; Group 2 airplanes have been modified by SB 55-005. Group 1 airplanes must inspect elevator, rudder and RH aileron hinge bolt installations within 14 days after the effective date of this AD and modify the Group 1 airplanes within 11 months. More information is available at tinyurl.com/45dty42w.