Document ID: chunk:federal_register_of_legislation:F2006L02501:body:0:p2
Version: federal_register_of_legislation:F2006L02501
Segment Type: other
Provision Reference: 
Character Range: 2890–3798

requirement 1 of this AD.

                2. At every subsequent shop visit where the HP turbine blades have been removed from the HP turbine disc.
             This Airworthiness Directive becomes effective on 31 August 2006.
Background:  HPT Discs recently inspected in accordance with the Engine Manual have exhibited cracks in the disc rim.  The discs have failed to meet the inspection acceptance criteria and have been returned to Rolls-Royce for engineering investigation.  This investigation has concluded that the cracks have resulted from scores within the cooling air holes in the disc rim that could have been introduced during new part manufacture or during overhaul of the disc.  The engineering investigation has also concluded that if this cracking was undetected then it could result in uncontained disc failure.

James Coyne
Delegate of the Civil Aviation Safety Authority

21 July 2006