Conclusion

We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting
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the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

We estimate that this AD will affect 1,022 engines installed on airplanes of U.S. registry. We also estimate that it would take about 2 workhours per engine to perform the actions, and that the average labor rate is $80 per workhour. Required parts would cost about $97,040 per engine. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $99,338,400.

Authority for This Rulemaking

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.

Regulatory Findings

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); 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.

We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 as follows: PART 39AIRWORTHINESS 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. The FAA amends Sec. 39.13 by adding the following new airworthiness directive:
20072105 International Aero Engines: Amendment 3915223. Docket No. FAA200523500; Directorate Identifier 2005NE46AD.
Effective Date
(a) This airworthiness directive (AD) becomes effective November 15, 2007.
Affected ADs
(b) None.
Applicability
(c) This AD applies to International Aero Engines (IAE) model V2500A1, V2522A5, V2524A5, V2527A5, V2527EA5, V2527MA5, V2530 A5, V2533A5, V2525D5, and V2528D5 turbofan engines with high pressure turbine (HPT) stage 2 air seals, part numbers (P/Ns) 2A0487, 2A1159, 2A1160, 2A3108, 2A3179, 2A3185, 2A3425, and 2A3596, installed. These engines are installed on, but not limited to, Airbus A319, A320, A321, and Boeing MD90 airplanes.
Unsafe Condition
(d) This AD results from a report that HPT stage 2 air seals have developed cracks. We are issuing this AD to prevent uncontained failure of the HPT stage 2 air seal.
Compliance
(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
Monitoring N2 Vibration on All IAE Model V2500A1 and V2522A5, V2524 A5, V2527A5, V2527EA5, V2527MA5, V2530A5, and V2533A5 Engines (f) For IAE model V2530A5 and V2533A5 engines operated at 30,000 or 33,000 pounds of thrust, or for model V2522A5, V2524A5, V2527A5, V2527EA5, and V2527MA5 engines that have ever operated in the 30,000 or 33,000 pound thrust range, begin monitoring for N2 vibration trend if the HPT stage 2 air seal reaches 4,000 cycles sincenew (CSN) or more.
(g) For IAE model V2500A1 and V2522A5, V2524A5, V2527A5, V2527EA5, and V2527MA5 engines operated below 30,000 pounds of thrust, begin monitoring for N2 vibration trend if the HPT stage 2 air seal reaches 6,000 CSN.
(h) Monitor N2 vibration trend of each engine for every 100 to 150 cycles of engine operation as follows:
(1) Use the Accomplishment Instructions of IAE Service Bulletin (SB) V2500ENG720500, Revision 1, dated July 14, 2006, to gather and monitor steadystate cruise N2 vibration data.
(2) For a trend that has a slope of 0.001 units per cycle or greater and less than 0.003 units per cycle, remove the seal 250 cycles from the point at which the slope begins to increase and do not reinstall it in any V2500 engine.
(3) For a trend that has a slope of 0.003 units per cycle or greater, remove the seal in 10 cycles and do not reinstall it in any V2500 engine.
(4) If a through crack is found in the front fillet radius of the HPT stage 2 air seal, remove the following:
(i) For the A1 model engine, remove the HPT stage 1 and 2 disks and HPT stage 1 rear air seals (64 per engine) and do not reinstall them in any V2500 engine.
(ii) For all A5 engine models, remove the HPT stage 1 disk and the HPT stage 1 rear air seals (64 per engine) and do not reinstall them in any V2500 engine.
(5) Use Section 3, Accomplishment Instructions, of IAE SB V2500 ENG720502, Revision 1, dated March 15, 2006, for removal
procedures.
Monitoring N2 Vibration on All IAE Model V2525D5 and V2528D5 Engines (i) For all IAE model V2500D5 series engines, begin monitoring for N2 vibration trend if the HPT stage 2 air seal reaches 6,000 CSN or more.
(j) Monitor N2 vibration trend of each engine for every 100 to 150 cycles of engine operation as follows:
(1) Use Section 3, Accomplishment Instructions, of IAE SB V2500 ENG720501, Revision 1, dated July 14, 2006, to gather and monitor the steadystate cruise N2 vibration data.
(2) If an increasing trend that has a slope of 0.0007 units per cycle or greater, and less than 0.002 units per cycle is observed, remove the HPT stage 2 air seal within 250 cycles from the point at which the slope begins to increase and do not reinstall it in any V2500 engine.
(3) If an increasing trend that has a slope of 0.002 units per cycle or greater is observed, remove the HPT stage 2 air seal within 10 cycles and do not reinstall it in any V2500 engine.
(4) If a through crack is found in the front fillet radius of the HPT stage 2 air seal of D5 model engines, remove the HPT stage 1 disk and HPT rear air seals (64 per engine) and do not reinstall them in any V2500 engine.
(5) Use Section 3, Accomplishment Instructions, of IAE SB V2500 ENG720502, dated March 15, 2006, for removal procedures.
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Removal of HPT Stage 2 Air Seals at Opportunity
(k) For all engines, when the HPT stage 2 air seal reaches 2,000 CSN, remove the HPT stage 2 air seal at the next separation of the HPT stage 1 and 2 rotors and do not reinstall it in any V2500 engine.
Definition
(l) For the purposes of this AD, ``At Opportunity'' is defined as when the engine is disassembled, the HPT stage 2 seal is exposed, and the HPT stage 1 and 2 rotors are separated after 2,000 CSN. (m) The Accomplishment Instructions of IAE SB V2500ENG720502, Revision 1, dated March 15, 2006, provide information on removing the HPT stage 2 air seal.
Alternative Methods of Compliance
(n) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.
Related Information
(o) Contact James Rosa, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; email: james.rosa@faa.gov, telephone (781) 2387152; fax (781) 2387199, for more information about this AD.
Material Incorporated by Reference
(p) You must use the Accomplishment Instructions (Section 3.) of International Aero Engines (IAE) Service Bulletin (SB) V2500ENG72 0500, Revision 1, dated July 14, 2006; IAE SB V2500ENG720501, Revision 1, dated July 14, 2006; or IAE SB V2500ENG720502, Revision 1, dated March 15, 2006, to perform the actions required by this AD. The Director of the Federal Register approved the incorporation by reference of these service bulletins in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact International Aero Engines AG, 400 Main Street, East Hartford, CT 06108; telephone: (860) 5655515; fax: (860) 5655510 for a copy of this service information. You may review copies at the FAA, New England Region, 12 New England Executive Park, Burlington, MA; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 2027416030, or go to: http://www.archives.gov/federalregister/cfr/ibrlocations.html.

Issued in Burlington, Massachusetts, on October 2, 2007. Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. E719924 Filed 101007; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT James Rosa, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone (781) 2387152; fax (781) 2387199.