Federal Aviation Administration, DOT.
Proposed rule; withdrawal.
This action withdraws a notice of proposed rulemaking (NPRM). That NPRM proposed a new airworthiness directive (AD) that applies to Rolls-Royce plc (RR) RB211 Trent 800 series turbofan engines. That proposed action would have required initial and repetitive borescope inspections of the high pressure-and-intermediate pressure (HP-IP) turbine internal and external oil vent tubes for coking and carbon buildup, and cleaning or replacing the vent tubes if necessary. Since we issued that NPRM, RR notified us that the RB211 Trent 800 series turbofan engines are significantly less susceptible to vent tube carbon build-up than the RB211 Trent 700 series turbofan engines. Repeat on-wing inspections therefore, are not required to maintain fleet safety. Accordingly, we withdraw the proposed rule.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7178; fax (781) 238-7199.End Further Info End Preamble Start Supplemental Information
The FAA proposed to amend 14 CFR part 39 with a proposed airworthiness directive (AD). The proposed AD applies to Rolls-Royce plc RB211 Trent 800 series turbofan engines. We published the proposed AD in the Federal Register on December 27, 2004 (69 FR 77144). That proposed action would have required initial and repetitive borescope inspections of the HP-IP turbine internal and external oil vent tubes for coking and carbon buildup, and cleaning or replacing the vent tubes if necessary. That proposed action resulted from a report of an RB211 Trent 700 series engine experiencing a disk shaft separation, overspeed of the intermediate pressure (IP) turbine rotor, and multiple blade release of IP turbine blades.
Since we issued that NPRM, RR notified us that data collected from a onetime inspection of 200 RB211 Trent 800 series turbofan engines shows that these engines are significantly less susceptible to vent tube carbon build-up than the RB211 Trent 700 series turbofan engines. The RB211 Trent 800 series engines had no evidence of significant accumulation. RR's analysis concluded that repeat on-wing inspections are not required to maintain fleet safety. The vent tube inspection and cleaning can be done at each shop visit. This will ensure that the probability of carbon blockage and spontaneous ignition will be negligible. Based on this analysis, RR has stated they will cancel Alert Service Bulletin RB.211-72-AE362, dated May 7, 2004.
Upon further consideration, we hereby withdraw the proposed rule based on RR's analysis and conclusion stated above.
Withdrawal of this notice of proposed rulemaking constitutes only such action, and does not preclude the agency from issuing another notice in the future, nor does it commit the agency to any course of action in the future.
Since this action only withdraws a notice of proposed rulemaking, it is neither a proposed nor a final rule. Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979) do not cover this withdrawal.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
Accordingly, we withdraw the notice of proposed rulemaking, FAA-2004-19930; Directorate Identifier 2004-NE-33-AD, published in the Federal Register on December 27, 2004 (69 FR 77144).Start Signature
Issued in Burlington, Massachusetts, on March 13, 2006.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. E6-3907 Filed 3-16-06; 8:45 am]
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