AD 2012-18-07

This AD is effective October 29, 2012.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of October 29, 2012.

For service information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ, phone: 011-44-1332-242424; fax: 011-44-1332-245418, or email: http://www.rolls-royce.com/contact/civil_team.jsp. You may view this service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA. For information on the availability of this material at the FAA, call 781-238-7125.

Alan Strom, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; phone: 781-238-7143; fax: 781-238-7199; email: alan.strom@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2012-06-23 (77 FR 20508, April 5, 2012). That AD applies to the specified products. The NPRM published in the Federal Register on May 3, 2012 (77 FR 26216). That NPRM proposed to continue to require initial and repetitive UIs of certain LP compressor blades identified by S/N. This AD requires the same actions but expands the population of blades.

We gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and the FAA's response to each comment.

Commenters RR and The Boeing Company (Boeing) requested that the initial inspection thresholds listed in Table 1 of the proposed AD be the same as those in RR ASB RB.211-72-AG244. Alternatively, RR and Boeing asked that we adjust the calendar months after the effective date of the AD to make them equivalent to the calendar dates in the ASB. RR claims that allowing parts to remain on wing longer than the times specified in the ASB will increase the risk of a fan blade failure before a crack is detected.

We do not agree. The number of months for compliance after the effective date of this AD is the same as in the EASA AD 2012-0025, dated February 8, 2012. Also, shortening the initial inspection thresholds now would require renotice and therefore delay implementation of the AD. We did not change the AD.

RR asked that we change the unsafe condition statement in the AD to indicate that the AD is being issued to prevent multiple blades from the same engine from failing. RR indicated that this change is needed because a single blade failure from the root is, by design, a contained event.

We agree because multiple blades in an engine may develop cracks and fail if not inspected. We changed the AD by revising the unsafe condition statement in paragraph (d) of the AD from: “We are issuing this AD to prevent LP compressor blades from failing due to blade root cracks, which could lead to uncontained engine failure and damage to the airplane” to “We are issuing this AD to prevent multiple LP compressor blades from failing due to blade root cracks, which could lead to uncontained engine failure and damage to the airplane.”

Commenter American Airlines (American) requested that we change paragraph (e)(3) from “* * * and paragraphs 1. through 3.B. of Appendix 1 of that ASB, or paragraphs 3.B.(1) through 3.B.(3) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244 * * *,” to “* * * and paragraphs 1. through 3.B. of Appendix 1 of that ASB, or paragraph 3.B.(3) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244 * * *.”. American argued that paragraphs 3.B.(1) and 3.B.(2), which require removal of the air intake fairing/spinner and spinner extension and annulus fillers, are not needed to resolve the unsafe condition noted in the AD.

We agree in part. We agree to remove the references to paragraphs 3.B.(1) and 3.B.(2) from the AD because it is not necessary to mandate the procedures used to remove the air intake fairing/spinner and spinner extension and annulus fillers. We disagree that removal of these parts does not need to be mentioned in the AD because these parts need to be removed before performing the UI. We therefore revised paragraph (e)(3) in the AD from: “Use paragraph 3.A.(2) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244, Revision 4, dated December 22, 2011, and paragraphs 1. through 3.B. of Appendix 1 of that ASB, or paragraphs 3.B.(1) through 3.B.(3) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244, Revision 4, dated December 22, 2011, and paragraphs 1. through 3.C. of Appendix 2 of that ASB, to perform the UIs.” to “Use paragraph 3.A.(2) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244, Revision 4, dated December 22, 2011, and paragraphs 1. through 3.B. of Appendix 1 of that ASB, or paragraphs 3.B.(3) of Accomplishment Instructions of RR ASB No. RB.211-72-AG244, Revision 4, dated December 22, 2011, and paragraphs 1. through 3.C. of Appendix 2 of that ASB, to perform the UIs. Prior to inspecting the blades per paragraph 3.B.(3) of the Accomplishment Instructions remove the air intake fairing/spinner and spinner extension and annulus fillers.”

American requested that paragraph (e)(6) of the AD be revised to read: “After the effective date of this AD, do not install any affected LP compressor blade that has reached the initial inspection threshold in Table 1, unless it has passed the UI required by this AD.” American indicated that the wording of the proposed AD implied that if a blade fails a visual inspection, it may not be reinstalled even if it passes a subsequent UI.

We agree. We revised the paragraph to read: “After the effective date of this AD, do not install any affected LP compressor blade that has reached the initial inspection threshold in Table 1 to paragraph (e), unless it has passed the UI required by this AD.” We also moved this paragraph to a separate Installation Prohibition paragraph (f).

American asked that the AD allow compressor blades inspected ultrasonically before the effective date of this AD using RR SB RB.211-72-E175, Revision 7, dated April 11, 2011, to be installed without further inspection. American indicated that the UI instructions in SB RB.211-E175, Revision 7, are identical to the UI instructions in ASB RB.211-72-AG244.

We agree. We changed the Credit for Previous Actions paragraph in the AD from, “You may take credit for the initial inspection that is required by paragraph (e)(1) of this AD if you performed the initial inspection before the effective date of this AD using RR ASB No. RB.211-72-AG244, dated August 7, 2009; ASB No. RB.211-72-AG244, Revision 1, dated January 26, 2010; ASB No. RB.211-72-AG244, Revision 2, dated August 18, 2011; or ASB No. RB.211-72-AG244, Revision 3, dated December 13, 2011,” to “You may take credit for the initial inspection that is required by paragraph (e)(1) of this AD if you performed the initial inspection before the effective date of this AD using RR ASB No. RB.211-72-AG244, dated August 7, 2009; ASB No. RB.211-72-AG244, Revision 1, dated January 26, 2010; ASB No. RB.211-72-AG244, Revision 2, dated August 18, 2011, ASB No. RB.211-72-AG244, Revision 3, dated December 13, 2011 or RB.211-72-E175, Revision 7, dated April 11, 2011.”

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We also determined that these changes will not increase the economic burden on any operator nor increase the scope of the AD.

Based on the service information, we estimate that this AD affects about 158 engines installed on airplanes of U.S. registry. We also estimate that it will take about 3 hours per engine inspection and six inspections will be needed per year. The average labor rate is $85 per work-hour. We estimate that one LP compressor blade per year will need replacement at a cost of about $82,000. Based on these figures, we estimate the annual cost of the AD on U.S. operators to be $323,740. Our cost estimate is exclusive of possible warranty coverage.

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.

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, I certify that this AD:

(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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by removing airworthiness directive (AD) 2012-06-23, Amendment 39-17004 (77 FR 20508, April 5, 2012), and adding the following new AD: