AD 2001-26-11

This amendment supersedes an existing airworthiness directive (AD) that is applicable to Rolls-Royce, plc RB211 Trent 800 series turbofan engines. That AD currently requires initial and repetitive ultrasonic inspections of low pressure compressor (LPC) fan blade roots for cracks, and replacement, if necessary, with serviceable parts. This amendment requires initial inspections at modified thresholds and repetitive inspections at reduced intervals from the current AD using new LPC fan blade inspection criteria, and requires renewal of dry film lubricant on removed blades. This amendment is prompted by reports that an in-service engine experienced LPC fan blade root cracking at a lower life than previously forecast, and, the manufacturer's further investigation that has led to a better understanding of the causes of fan blade root cracking. The actions specified in this AD are intended to prevent LPC fan blade failure due to cracking, which could result in multiple fan blade release, uncontained engine failure, and possible damage to the airplane.

Final rule; request for comments

2001-26-11 Rolls-Royce, plc: Amendment 39-12575. Docket No. 98-ANE-33-AD. Supersedes AD 2000-24-26, Amendment 39-12033.

Applicability

This airworthiness directive (AD) is applicable to Rolls-Royce plc (RR) RB211 Trent 875, RB211 Trent 877, RB211 Trent 884, RB211 Trent 892, and RB211 Trent 892B series turbofan engines, with low pressure compressor (LPC) fan blades, part numbers (P/N's) FK23750, FK25975, FK25548, or FK26757 installed. These engines are installed on, but not limited to Boeing 777 series airplanes.

Note 1: This AD applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (i) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance

Compliance with this AD is required as indicated, unless already done.

To prevent LPC fan blade failure due to cracking, which could result in multiple fan blade release, uncontained engine failure, and possible damage to the airplane, do the following:

Initial Inspection

(a) Ultrasonically inspect the dovetail roots of LPC fan blades for cracks, in accordance with Appendix 1 (Method A) of RR Service Bulletin (SB) RB.211-72-C445, Revision 7, dated May 10, 2001, at the Initial Inspection Threshold cyclic times listed in the following Table 1 of this AD:

Table 1.--Inspection Schedule

Engine model (rating)
Initial Inspection threshold, cycles-since-new (CSN)
Inspection intervals, cycles-since-last inspection (CSLI)
Part life, threshold, CSN
(1) Trent 875
3,000
400
4,200
(2) Trent 877
2,000
350
3,050
(3) Trent 884
1,500
350
2,200
(4) Trent 892 and Trent 892B
900
200
1,300

Dry Film Lubricant Renewal

(b) Apply an approved dry film lubricant to LPC fan blade roots of blades inspected by Method A. Procedures for renewing the dry film lubricant on the blade roots are specified in the AMM task 72-31-11-300-801-R00 (Repair Scheme FRS A031 by air spray method only) or engine manual 72-31-11-R001 (Repair Scheme FRS A028). For purposes of this AD, approved lubricants are Dow Corning 321R (Rolls-Royce (RR) Omat item 4/52), Rocol Dry Moly Spray (RR Omat item 4/52), Molydag 709 (RR Omat item 444), or PL.237/R1 (RR Omat item 4/43).

Repetitive Inspections

(c) Except for the first inspection after exceeding the Part Life Threshold listed in Table 1 of this AD, ultrasonically inspect the dovetail roots of LPC fan blades for cracks and renewdry film lubricant when specified in accordance with Appendix 1 (Method A) or Appendix 2 (Method B) of RR SB RB.211-72-C445, Revision 7, dated May 10, 2001, and the Inspection Intervals listed Table 1 of this AD.

First Inspection After Exceeding Part Life Threshold

(d) For the first inspection after exceeding the Part Life Threshold listed in Table 1 of this AD, ultrasonically inspect the dovetail roots of LPC fan blades for cracks in accordance with Appendix 1 (Method A) of RR SB RB.211-72-C445, Revision 7, dated May 10, 2001. Thereafter, the repetitive inspections may be done using either Appendix 1 (Method A) or Appendix 2 (Method B), as specified in paragraph (c) of this AD.

Fan Blades Exceeding Initial Inspection Threshold

(e) For blades that have, on the effective date of the AD, more cycles since installation than the initial compliance criteria in Table 1, inspect blades within 100 cycles in service after the effective date of this AD.

Engine Rating Changes

(f) For an engine that has changed its rating, inspect fan blades at the correct cycle time as follows:

(1) From higher rating to lower rating, inspect fan blades before further flight, as specified in this AD and reinspect at the interval applicable to the lower rating.

(2) From lower rating to higher rating, inspect fan blades at intervals applicable to the higher rating.

Method A Acceptance Criteria

(g) For Method A, replace blades that do not meet the acceptance criteria in Appendix 1 of RR SB RB.211-72-C445, Revision 7, dated May 10, 2001.

Method B Acceptance Criteria

(h) For Method B, for blades that do not meet the acceptance criteria in Appendix 2 of RR SB RB.211-72-C445, Revision 7, dated May 10, 2001, remove blades and ultrasonically inspect the dovetail roots for cracks in accordance with Appendix 1 (Method A) of RR SB RB.211-72-C445, Revision 7, dated May 10, 2001.

Alternative Methods of Compliance

(i) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office (ECO). Operators must submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

Special Flight Permits

(j) Special flight permits may be issued in accordance with Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be done.

Documents That Have Been Incorporated by Reference

(k) The inspection must be done in accordance with Rolls-Royce plc Service Bulletin(SB) No. RB.211-72-C445, Revision 7, dated May 10, 2001. This incorporation by reference was approvedby the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Rolls-Royce plc, Technical Publications Department, PO Box 31, Derby, England DE248BJ; telephone 44 1332 242424, fax, 1332 249936. Copies may be inspected, by appointment, at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Note 3: The subject of this AD is addressed in Civil Aviation Authority airworthiness directive AD 003-04-98, issued on May 10, 2001.

Effective Date

(l) This amendment becomes effective on January 30, 2002.

On November 30, 2000, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 2000-24-26, Amendment 39-12033 (65 FR 77778, December 13, 2000), applicable to Rolls-Royce, plc RB211 Trent 875, RB211 Trent 877, RB211 Trent 884, RB211 Trent 892, and RB211 Trent 892B series turbofan engines, to require initial and repetitive ultrasonic inspections of low pressure compressor (LPC) fan blade roots for cracks, and replacement, if necessary, with serviceable parts. This AD requires initial inspections at modified thresholds and repetitive inspections at reduced intervals from the current AD using new LPC fan blade inspection criteria, and requires renewal of dry film lubricant on removed blades.

Since AD 2000-24-26 was issued, the Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (UK), advises that an in-service engine experienced LPC fan blade root cracking at a lower life than previously forecast.The manufacturer's analysis of this new event has produced an improved understanding of the relationship between engine climb and takeoff speeds, and their effect on the crack initiation mechanism. These changes are the result of an improved understanding of the crack propagation mechanism and the latest service operational data.

Manufacturer's Service Information

Rolls-Royce, plc has issued Service Bulletin (SB) No. RB.211-72-C445, Revision 7, dated May 10, 2001, that specifies initial inspections at modified thresholds and repetitive inspections at reduced intervals from the current AD using new LPC fan blade inspection criteria, and requires renewal of dry film lubricant on removed blades. The CAA classified this service bulletin as mandatory and issued AD 003-04-98, dated May 10, 2001, in order to assure the airworthiness of these Rolls-Royce, plc engines in the UK.

Bilateral Airworthiness Agreement

This engine model is 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. 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.

FAA's Determination of an Unsafe Condition and Required Actions

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. Since an unsafe condition has been identified that is likely to exist or develop on other Rolls-Royce, plc RB211 Trent 875, RB211 Trent 877, RB211 Trent 884, RB211 Trent 892, and RB211 Trent 892B series turbofan engines of the same type design, this AD is being issued to prevent LPC fan blade failure, which could result in multiple fan blade release, uncontained engine failure, and possible damage to the airplane. This AD requires initial inspections at modified thresholds and repetitive inspections at reduced intervals from the current AD using new LPC fan blade inspection criteria, and requires renewal of dry film lubricant on removed blades. The actions are required to be done in accordance with the service bulletin described previously.

Immediate Adoption of This AD

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 precededby 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 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 appointment, 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 action must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-ANE-33-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Analysis

This final 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 final rule.

For the reasons discussed above, I certify that thisaction (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) if promulgated, 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained by contacting 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-12033 (65 FR 77778 December 13, 2000) and by adding a new airworthiness directive, Amendment 39-12575, to read as follows: