AD 95-04-02

This amendment adopts a new airworthiness directive (AD), applicable to certain Rolls- Royce, plc RB211-524 series turbofan engines, that requires a one-time modification of the nozzle guide vane (NGV) assembly to incorporate vane core reinforcement inserts which would prevent release of the stage 2 NGV seal ring, rotor contact, and severance of the rotor drive arm. This amendment is prompted by a report of an uncontained stage 1 low pressure turbine failure. The actions specified by this AD are intended to prevent release of the stage 2 NGV seal ring, which could result in an uncontained engine failure.
The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of May 8, 1995.

Final rule.

95-04-02 Rolls-Royce, plc: Amendment 39-9154. Docket 93-ANE-40.
Applicability: Rolls-Royce, plc (R-R) Models RB211-524B-02, -524B-B-02, -524B3-02, -524B2-19, -524B2-B-19, -524C2-19, and -524C2-B-19 turbofan engines, installed on but not limited to Boeing 747 series and Lockheed L-1011 series aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent release of the stage 2 nozzle guide vane (NGV) seal ring, which could result in an uncontained engine failure, accomplish the following:
(a) For engines installed on Boeing 747 series aircraft, modify the NGV assembly in accordance with R-R Mandatory Service Bulletin (SB) No. RB.211-72-9672, Revision 1, dated November 6, 1992, at the next shop visit, but not later than 9 months after the effective date of this airworthiness directive (AD), whichever occurs first.
(b) For engines installed on Lockheed L-1011 series aircraft, modify the NGV assembly in accordance with R-R Mandatory SB No. RB.211-72-9672, Revision 1, dated November 6, 1992, at the next shop visit, but not later than 20 months after the effective date of this AD, whichever occurs first.
(c) For the purpose of this AD, a shop visit is defined as an engine removal where engine maintenance entails separation of pairs of mating engine flanges or the removal of a disk, hub, or spool.
(d) 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. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(e) Special flight permits may be issued in accordance with sections 21.197 and21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.
(f) The modification shall be done in accordance with the following SB:

Document No.
Pages
Revision
Date
R-R SB No. RB.211-72-9672
1-31
1
November 6, 1992
R-R SB Supplement
1-2
1
November 6, 1992
Total pages: 33.

This incorporation by reference was approved by 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, P.O. Box 31, Derby, England DE2 8BJ; telephone 44-332-242424, fax 44-332-249936. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief 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.
(g) This amendment becomes effective on May 8, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Rolls-Royce, plc (R-R) RB211-524 series turbofan engines was published in the Federal Register on October 4, 1993 (58 FR 51585). That action proposed to require a one-time modification of the nozzle guide vane (NGV) assembly to incorporate vane core reinforcement inserts which would prevent release of the stage 2 NGV seal ring, rotor contact, and severance of the rotor drive arm in accordance with R- R Mandatory Service Bulletin (SB) No. RB.211-72-9672, Revision 1, dated November 6, 1992.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
One commenter concurs with the rule as proposed.
One commenter states that the proposed rule should provide separate compliance times for spare engines. The commenter further states that the proposed rule notes that no U.S. registry engines would be affected. The commenter has one affected spare engine, and states that an acceptable level of safety would be maintained provided the spare engine is modified within 20 months of installation. The FAA concurs in part. The FAA has revised the economic analysis of this final rule to include the one domestic spare engine. However, the FAA does not concur with the proposal to require modifying spare engines within 20 months after installation on Lockheed L-1011 aircraft, or at the next shop visit. The FAA has determined that the acceptable level of safety maintained by this AD is based on total fleet compliance within a finite period after AD issuance. The commenter's proposal to modify spare engines within 20 months after installation or at the next shop visit could allow indefinite operation of unmodified engines, if an engine were removed for use as a spare engine and subsequently installed without undergoing a shop visit. Therefore, the FAA concludes that the compliance timetable originally provided in the NPRM is appropriate to maintain an acceptable level of safety.
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the change described previously. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.
There are approximately 300 R-R RB211-524 series turbofan engines of the affected design in the worldwide fleet. The FAA estimates that 1 spare engine of U.S. registry will be affected by this AD, that it will take approximately 37 work hours per engine to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $2,420 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $4,640.
The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. 39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive: