AD 2015-20-09

This AD is effective November 18, 2015.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of November 18, 2015.

For service information identified in this proposed AD, contact General Electric Company, GE Aviation, Room 285, One Neumann Way, Cincinnati, OH, 45215; phone: 513-552-3272; email: aviation.fleetsupport@ ge.com. 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.

Christopher McGuire, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; phone: 781-238-7120; fax: 781-238-7199; email: chris.mcguire@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2001-18-06, Amendment 39-12432 (66 FR 47575, September 13, 2001, (“AD 2001-18-06”) and AD 2008-22-16, Amendment 39-15712 (73 FR 63629, October 27, 2008, (“AD 2008-22-16”). AD 2001-18-06 and AD 2008-22-16 applied to certain GE CT58 turboshaft engines. The NPRM published in the Federal Register on May 1, 2015 (80 FR 24852). The NPRM was prompted by GE updating the life limits of compressor spools. GE also updated the calculation method for the life consumption of compressor spools and of life-limited rotating parts flown in Utility operations. This update resulted in generally reduced lives for compressor spools and all other life-limited parts used in Utility operations. The NPRM proposed to consolidate AD 2001-18-06 and AD 2008-22-16, and further reduce the life capability of certain parts. We are issuing this AD to prevent failure of life-limited rotating parts, uncontained part release, damage to the engine, and damage to the aircraft.

We reviewed GE CT58 Alert Service Bulletin (ASB) No. SB 72-A0162, Revision 16, dated January 7, 2015. The service information describes procedures for calculating life limits for the affected life-limited rotating parts. This service information is reasonably available because the interested parties have access to it through their normal course of business or see ADDRESSES for other ways to access this service information.

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

AAR Airlift Group (AAR) requested replacement of the current method for determining reduced life limits because current limits do not agree with operators field experience. AAR independent testing revealed that expired critical rotating parts showed no fatigue cracks.

We disagree. FAA-approved life limits for rotating parts are specified to prevent fatigue crack initiation, using conservative analytical margins. The number of parts that AAR had inspected would not be sufficient to show a likelihood of part cracking consistent with FAA regulatory guidelines for rotating part life limits. We did not change this AD.

AAR disagrees that the NPRM has minimal impact on their company. AAR stated that their cost per flight would increase and company revenue would be reduced.

We agree that this AD will impose an economic impact to operators. How an operator absorbs or passes on the cost is left to the operator to determine. We did not change this AD.

Since we issued the proposed AD, we discovered that ASB formatting discrepancies exist due to documentation changes implemented by GE. We changed paragraphs (e)(2), (e)(3), and (e)(4) to reflect the correct SB paragraph numbers.

We reviewed the relevant data and determined that air safety and the public interest require adopting this AD as proposed.

We estimate that this AD will affect about 60 engines installed on aircraft of U.S. registry. The average pro-rated cost of the life-limited rotating parts is $20,000. The average labor rate is $85 per hour. Based on these figures, we estimate the cost of this AD on U.S. operators to be $8,715,000.

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 to the extent that it justifies making a regulatory distinction, 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:

a. Removing airworthiness directives (AD) 2001-18-06, Amendment 39-12432 (66 FR 47575, September 13, 2001) (“AD 2001-18-06”); and AD 2008-22-16, Amendment 39-15712 (73 FR 63629, October 27, 2008) (“AD 2008-22-16”), and

b. Adding the following new AD: