The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (UK), recently notified us that an unsafe condition might exist on RR RB211 Trent 768- 60, Trent 772-60, and Trent 772B-60 turbofan engines. The CAA advises that two RB211 Trent 700 series engines were removed due to high oil consumption. Investigation revealed that damaged heat shields caused fretting of the HP-IP internal oil vent tube and scavenge tube. A previous service incident revealed that ingestion of HP cooling air into either the scavenge tube or the vent tube can over pressurize the HP-IP turbine bearing chamber. The overpressure can cause oil to eject from the rear of the chamber. If the ejected oil ignites, the fire can trigger fracture of the IP shaft, overspeed of the IP turbine, and uncontained engine failure.
Relevant Service Information
We have reviewed and approved the technical contents of RR Alert Service Bulletin RB.211-72-AE792, dated July 8, 2005, that describes procedures for initial and repetitive borescope inspections of the HP- IP turbine bearing internal oil vent tube, scavenge tube, and tube heat shields for wear and cracking. We have also reviewed and approved the technical contents of RR Service Bulletin RB.211-72-E708, Revision 2, dated September 6, 2005, that describes procedures for installing a new or modified HP-IP turbine bearings support. The CAA classified these service bulletins as mandatory and issued AD G-2005-0016 in order to ensure the airworthiness of these RR RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines in the UK.
Bilateral Airworthiness Agreement
These RR RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines are manufactured in the UK and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Underthis bilateral airworthiness agreement, the CAA kept the FAA informed of the situation described above. We have examined the findings of the CAA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
FAA's Determination and Requirements of This AD
Although no airplanes that are registered in the United States use these RR RB211 Trent 768-60, Trent 772-60,
and Trent 772B-60 turbofan engines, the possibility exists that the engines could be used on airplanes that are registered in the United States in the future. The unsafe condition described previously is likely to exist or develop on other RR RB211 Trent 768-60, Trent 772- 60, and Trent 772B-60 turbofan engines of the same type design. We are issuing this AD to prevent oil ejecting from the HP-IP turbine bearings chamber and igniting. Burning oil can cause the IP shaft to fracture, the IP turbine to overspeed,and possible uncontained failure of the engine. This AD requires:
Initial and repetitive borescope inspections of the HP-IP turbine bearing internal oil vent tube, scavenge tube, and tube heat shields for wear and cracking; and
Removing tubes from service if found with any cracks beyond serviceable limits; and
As terminating action to the repetitive inspections required by the AD, at the next IP (05) module overhaul, but before May 31, 2010, removing the HP-IP bearings support introduced prior to Rolls-Royce Modification 72-E708, and replacing with serviceable parts.
You must use the service information described previously to perform the actions required by this AD.
FAA's Determination of the Effective Date
Since there are currently no domestic operators of this engine model, notice and opportunity for public comment before issuing this AD are unnecessary. A situation exists that allows the immediate adoption of this regulation.
Comments InvitedThis AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to send us any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "AD Docket No. FAA-2006-23605; Directorate Identifier 2005-NE-48-AD'' in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it.
We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of the DMS Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.
Examining the AD Docket
You may examine the docket that contains the AD, any comments received, and any final disposition in person at the Docket Management Facility Docket Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5227) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the DMS receives them.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
Regulatory Findings
We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, Icertify that the regulation:
1. Is not a "significant regulatory action'' under Executive Order 12866;
2. Is not a "significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
We prepared a summary of the costs to comply with this AD and placed it in the AD Docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Under the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec.39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive: