The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (UK), recently notified the Federal Aviation Administration (FAA) that an unsafe condition may exist on Rolls-Royce plc (RR) RB211 Trent 768- 60, Trent 772-60, and Trent 772B-60 series turbofan engines having common nozzle assembly P/N FK16544 or FK16558. The CAA received reports of cracking and rivet loss on the outer and inner skin of the common nozzle assembly, with two reports of inner skin detachment. Rolls-Royce has determined that cracks and detachment of inner skin, and cracks of outer skin occurred due to a combination of missing rivets, loose rivets, and high stress levels on common nozzle assemblies with a high number of flight cycles. This condition, if not corrected, could result in inner skin detachment, release of common nozzle assembly debris from the engine, and possible damage to the airplane control surfaces. The compliance times specifiedin this AD are based on Rolls-Royce service bulletin criteria and CAA recommendations.
Manufacturer's Service Information
RR has issued Mandatory Service Bulletin (MSB) No. RB.211-78-C931, Revision 1, dated June 13, 2000, that specifies procedures for initial visual inspections of inner and outer skin, including allowable limits, for cracks, missing rivets, and loose rivets. The MSB also specifies repair for common nozzle assemblies that are out of limits. The MSB also specifies on common nozzle assemblies with more than 1,500 cycles-since-new, initial visual inspections for cracks in inner and outer skins, missing rivets, loose rivets not later than 500 flight hours after release of AD, and repetitive inspections within 500 flight hours since the last inspection. The CAA classified this MSB as mandatory and issued airworthiness directive (AD) 005-06-2000 in order to ensure the airworthiness of these engines in the UK.
Bilateral Airworthiness Agreement
This engine modelis manufactured in the UK and is 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. As required by this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, reviewed all available information, and determined that AD action is necessary for engines of this type design that could be used on airplanes certificated for operation in the United States.
Required Actions
Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design that could be used on airplanes registered in the United States, this AD requires initial and repetitive in-service visual inspections of the common nozzle assembly to detect cracks, missing rivets, and loose rivets, including allowable acceptance limits. This AD also requires repair for common nozzle assemblies that are out of limits. The actions must be done in accordance with the MSB described previously.
Immediate Adoption
A situation exists that allows the immediate adoption of this regulation. Since there are currently no domestic operators of this engine model, notice and opportunity for prior public comment are unnecessary.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted to the address specified under the caption "ADDRESSES". All communications received on or before the closing date for comments will be considered, and this rule may beamended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 2000-NE-37-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
This proposal does not have federalism implications, as defined in Executive Order (EO) 13132, because it would not have 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposal.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under EO 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation willbe prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES".
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to 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.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: