The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (U.K.), recently notified the FAA that an unsafe condition may exist on Rolls-Royce plc. (RR) RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines with fan blade part numbers (P/N's) FK22580, FK23411, FK25441, and FK25968 installed. The CAA received a report of multiple fan blade root cracks in a factory engine. A recent inspection of a set of fan blades from a factory fleet leader test engine has identified small cracks in the blade roots on the convex root flank. To date, this is the only engine that has exhibited the blade root cracks. This condition, if not corrected, could result in possible multiple fan blade failures, which could result in an uncontained engine failure and damage to the airplane.
Manufacturer's Service Information
Rolls-Royce plc (RR) has issued service bulletin (SB) No. RB.211-72-C878, Revision 1, dated December 10, 1999, that specifies procedures for ultrasonic inspections for cracks in fan blade dovetail roots. The CAA classified this SB as mandatory and issued airworthiness directive (AD) 003-11-99 in order to assure the airworthiness of these engines in the U.K. Differences Between This AD and the Manufacturer's Service Information
This AD applies only to those engines with fan blades having four specific part numbers. The manufacturer's service bulletin is not limited in that fashion. The FAA expects that future changes in the design of the affected fan blades will eliminate the need for the required inspections and that those newer fan blades will have different part numbers. The installation of the newer part number will therefore have the effect of removing the engine from the applicability of this AD.
Bilateral Airworthiness Agreement
This engine model is manufactured in the U.K. 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. Pursuant to 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 products of this type design that are certificated for operation in the United States.
Requirements of this AD
Although none of these affected engine models are used on any airplanes that are registered in the United States, the possibility exists that the engine models could be used on airplanes that are registered in the United States in the future. Because an unsafe condition has been identified that is likely to exist or develop on other RR RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 series turbofan engines of the same type design, with fan blade P/N's FK22580, FK23411, FK25441, and FK25968 installed, this ADrequires:
- Initial ultrasonic inspections within 200 cycles after the effective date of this AD, or within 200 cycles of achieving 2,800 cycles since new, whichever is later; and
- Repetitive ultrasonic inspection of the fan blade root within 340 cycles since the last inspection. The actions are required to be completed in accordance with the service bulletin described previously.
Immediate Adoption
Since there are currently no domestic operators of this engine model, notice and opportunity for prior public comment are unnecessary. Therefore, a situation exists that allows the immediate adoption of this regulation.
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 maydesire. Communications should identify the Rules Docket number and be submitted in triplicate 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 be amended 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-XX-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
This proposed rule does not have federalism implications, as defined in Executive Order 13132, because it would 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposed rule.
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 Executive Order 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 will be 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: