Document ID: chunk:federal_register_of_legislation:F2006B06368:body:0:p2
Version: federal_register_of_legislation:F2006B06368
Segment Type: other
Provision Reference: 
Character Range: 2723–5441

(Continued)

b.        If cracks are found exceeding the limits below, replace the duct with a serviceable part;

                    1. If 3 or less cracks are found, and the total cumulative length of the cracks exceeds 2 inches; or

                    ii.        If any one crack exceeds 1 inch in length; or

                    iii.      If any 2 cracks are separated by less than 6 times the longest crack (6L) or 3 inches or less, whichever is the closest separation; or

                    iv.      If more than 3 cracks are found.

                 c.         If cracks are found that are within the limits set by requirement 4b(i) through
                 (iv) of this Directive, mark all allowable cracks on the duct with a suitable metal marking material; and record the length of the crack, location, number of duct operating hours, and time since overhaul; and

                    1. Repeat the inspection and replace ducts exceeding the limits of Requirement 4b(i) through (iv) of this Directive;

                    ii.        Monitor the growth of existing cracks. For cracks exceeding a growth rate of 0.015 inches per hour time in service since the last inspection, replace the duct with a serviceable part.

            Note 1: Canadian AD CF 2002-47 refers.

            Note 2: Suitable marking materials can be found in the PWC Engine Manual.

            Note 3: A replacement duct is one that meets the acceptability limits of this Directive.

              Compliance: 1. At the next shop visit or within 150 flight hours from the effective date of this Directive, whichever occurs first.

              2.        a. At the completion of Requirement 1 of this Directive.

              b. At the next overhaul.

              3.        Prior to further flight.

              4.        a. At intervals not to exceed 150 flight hours.

b.        Prior to further flight.

                 c.         At intervals not to exceed 25 flight hours.

            This Airworthiness Directive becomes effective on 20 March 2003.

Pratt and Whitney Canada Turbine Engines - PT6A Series

 AD/PT6A/32 (Continued)

            Background: This Directive requires the inspection of certain turbine exhaust ducts for cracks. The cracks have developed following repairs using a different welding process. Excessive cracking of the turbine exhaust duct could lead to reduction gearbox separation and/or decoupling of the power turbine shaft, which could in turn lead to the release of turbine blades.

 James Coyne
 Delegate of the Civil Aviation Safety Authority 3 February 2003

 The above AD is notified in the Commonwealth of Australia Gazette on 26 February 2003.