AD 2008-11-19 Airworthiness Directives; Rolls-Royce plc (RR) Models Trent 768-60, 772-60, 772B-60, and 772C-60 Turbofan Engines

This AD applies to Rolls-Royce plc models Trent 768-60, 772-60, 772B-60, 772C-60 turbofan engines with intermediate pressure (IP) turbine discs, part number (P/N) FK20795, that have a serial number specified in Table 1 of this AD, installed. These engines are installed on, but not limited to, Airbus 330 series airplanes. Reason (d) Three Trent 700 IP Turbine discs that exhibited signs of wear at the bore following failure of the bearing chamber sealing sleeve were returned to service. This was based on the fact that Non-Destructive testing (NDT) did not reveal micro cracking on the affected disc areas. Further engineering investigation considered that, although no micro cracking had been found, the worn disc bore surfaces would have an associated fatigue penalty compared to an unaffected bore. A crack developing from these rubbed surfaces could potentially lead to a disc burst. As the described wear, present at the bores of those three discs, presents a potentially unsafe condition, this Airworthiness Directive requires identification of the three affected serial numbers of IP Turbine Discs (P/N FK20795) and removal from service prior to attaining a certain number of cycles, as indicated. We are issuing this AD to prevent a failure of the IP turbine disc that could result in an uncontained failure of the engine and possible damage to the airplane.

Unless already done, do the following actions. (1) The affected IP Turbine Discs, P/N FK20795, must be removed from service prior to attaining the following number of Cycles Since New (CSN): Table 1.—IP Turbine Discs by Engine Serial Number and Disc Serial Number Serial No. Removal limit in CSN CREB452 7,960 CREB216 7,930 CREB322 7,500 (2) For detailed instructions, refer to Rolls-Royce RB211 Propulsion System Non-Modification Service Bulletin RB211-72- AF734 original issue, section 3. Accomplishment Instructions. FAA AD Differences (f) None. Other FAA AD Provisions (g) Alternative Methods of Compliance (AMOCs): The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Related Information (h) Refer to MCAI EASA Airworthiness Directive 2007-0267-E, dated October 8, 2007, and RR Alert Service Bulletin RB.211-72-AF734, dated October 3, 2007, for related information. (i) Contact James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: james.lawrence@faa.gov ; telephone (781) 238-7176; fax (781) 238-7199, for more information about this AD. Material Incorporated by Reference (j) None. Issued in Burlington, Massachusetts, on May 23, 2008. Robert G. Mann, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. E8-12061 Filed 5-29-08; 8:45 am] BILLING CODE 4910-13-P

Unless already done, do the following actions. (1) The affected IP Turbine Discs, P/N FK20795, must be removed from service prior to attaining the following number of Cycles Since New (CSN): Table 1.—IP Turbine Discs by Engine Serial Number and Disc Serial Number Serial No. Removal limit in CSN CREB452 7,960 CREB216 7,930 CREB322 7,500 (2) For detailed instructions, refer to Rolls-Royce RB211 Propulsion System Non-Modification Service Bulletin RB211-72- AF734 original issue, section 3. Accomplishment Instructions. FAA AD Differences (f) None. Other FAA AD Provisions (g) Alternative Methods of Compliance (AMOCs): The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Related Information (h) Refer to MCAI EASA Airworthiness Directive 2007-0267-E, dated October 8, 2007, and RR Alert Service Bulletin RB.211-72-AF734, dated October 3, 2007, for related information. (i) Contact James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: james.lawrence@faa.gov ; telephone (781) 238-7176; fax (781) 238-7199, for more information about this AD. Material Incorporated by Reference (j) None. Issued in Burlington, Massachusetts, on May 23, 2008. Robert G. Mann, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. E8-12061 Filed 5-29-08; 8:45 am] BILLING CODE 4910-13-P