Airworthiness Directives; Pratt & Whitney Canada Corp. Turboshaft Engines

We are adopting a new airworthiness directive (AD) for certain serial number Pratt & Whitney Canada Corp. PW206B, PW206B2, PW206C, PW207C, PW207D, PW207D1, PW207D2, and PW207E turboshaft engines. This AD was prompted by the discovery that certain power turbine (PT) disks were made to specific heat codes that may not achieve the maximum in- service life. This AD requires re-identification of the PT disk to a part number (P/N) with a lower life limit. We are issuing this AD to prevent possible uncontained PT disk failure and loss of helicopter control.