Document ID: chunk:federal_register_of_legislation:F2006L01464:body:0:p3
Version: federal_register_of_legislation:F2006L01464
Segment Type: other
Provision Reference: 
Character Range: 6289–9098

cyclic life criteria is currently at shop visit; and if, at the effective date of this Airworthiness Directive, it has not yet been reinstalled into the Combustion Outer Case, then the HP turbine disc must be inspected in accordance with the requirements of this Airworthiness Directive at the current shop visit.

   Table 2
   Part No  Serial No   Part No  Serial No
   UL29473  LAQDY6043   UL29472  LQDY9125
   UL29473  LAQDY6048   UL29472  LQDY9554
   UL29473  LAQDY6079   UL29472  LQDY9582
   UL29473  LDRCZ10057  UL29472  LQDY9895
   UL29473  LDRCZ10264  UL29472  LQDY9910
   UL29473  LDRCZ10415  UL29472  LQDY9947
   UL29473  LDRCZ11402  UL29472  LQDY9960
   UL29473  LDRCZ11425  UL24994  LQDY6777

             UL29473  LDRCZ11497  UL24994  LQDY6792
             UL29473  LDRCZ11663  UL24994  LQDY6859
             UL29473  LDRCZ11679  UL24994  LQDY6860
             UL29473  LDRCZ12301  UL24994  LQDY6866
             UL29473  LDRCZ12308  UL24994  LQDY6869
             UL29473  LDRCZ12316  UL24994  LQDY6934
             UL29473  LDRCZ12319  UL24994  LQDY6946
             UL29473  LQDY6957    UL24994  LQDY6963
             UL29473  LQDY9075    UL23166  LQDY6745
             UL29473  LQDY9084    UL23166  LQDY6846
             UL29473  LQDY9557    UL23166  LQDY6848
             UL29473  LQDY9906    UL23166  LQDY6954
             UL29473  LQDY9956    FK24790  LDRCZ12492
             UL29473  LQDY9970    FK24790  LDRCZ12694
             UL29473  LQDY9985

             This Amendment becomes effective on 11 May 2006.
Background:  A population of HP turbine discs that were manufactured between 1989-1999 and which were subject to possible machining anomalies, were believed to have an increased chance of suffering from cooling air hole cracking, compared to the general fleet population of HP turbine discs.  As a result of this risk, Rolls-Royce issued Non-Modification Service Bulletin (NMSB) 72-C816, recommending in-service inspections of the subject discs.

             Recently an RB211 HP turbine disc has been found with a crack which had propagated further than expected from the risk model that was used to establish the original inspection defined in the above NMSB.  This has led to the need for a revision of the original inspection requirements.

             An HP turbine disc fracture would be uncontained and create a potential unsafe condition.  Accordingly, this AD introduces revised inspection requirements to reflect the increased risk of HP turbine disc cracking and potential disc fracture.

   This amendment corrects serial numbers and part numbers detailed in Table 1 and clarifies the compliance statements.

   The original issue of this AD was to become effective on 11 May 2006.

James Coyne
Delegate of the Civil Aviation Safety Authority

8 May 2006