Federal Aviation Administration (FAA), DOT.
The FAA is adopting a new airworthiness directive (AD) for General Electric Company (GE) CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and -402 turboshaft engines with certain serial numbers (SNs) of stage 1 compressor disks, part number (P/N) 5001T20P01, installed. This AD requires removing certain stage 1 compressor disks from service before reaching a reduced low-cycle-fatigue (LCF) life limit for those affected disks of 2,100 hours time-since-new (TSN) or by December 31, 2008, whichever occurs first. This AD results from two reports of low blade tip clearances in the compressor. We are issuing this AD to prevent LCF cracking and failure of the stage 1 compressor disk, an uncontained engine failure, and damage to the helicopter.
This AD becomes effective March 29, 2005.
Contact GE Aircraft Engines Customer Support Center, M/D 285, 1 Neumann Way, Evendale, OH 45215, telephone (513) 552-3272; fax (513) 552-3329, e-mail GEAE.email@example.com, for the service information identified in this AD.
You may examine the AD docket at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA. You may examine the service information, at the FAA, New England Region, Office of the Regional Counsel, 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 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Norman Brown, Senior Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone 781-238-7181; fax 781-238-7199.End Further Info End Preamble Start Supplemental Information
The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to GE CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and -402 series turboshaft engines with certain SNs of stage 1 compressor disks, P/N 5001T20P01, installed. We published the proposed AD in the Federal Register on February 26, 2004 (69 FR 8875). That action proposed to require removing certain stage 1 compressor disks from service before reaching a reduced LCF life limit for those affected disks of 2,100 hours TSN or by December 31, 2008, whichever occurs first.
Examining the AD Docket
You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.
We provided the public the opportunity to participate in the development of this AD. We have considered the comments received, which are all from GE.
Request To Change the Number of U.S. Engines Affected
One commenter, GE, requests that we change the estimated number of affected engines installed on helicopters of U.S. registry from 45 to 30. The commenter states that this number is a more accurate estimate of engines in the U.S. and affects the total cost of disk replacement by one third. GE bases this quantity change on their engine tracking system.
We agree, and have changed that number in the final rule based on GE's estimate of the number of affected engines.
Request To Add “Surplus Military” Before References to T58
GE requests that we add “surplus military” before all references to “T58-GE-5”, to differentiate those engines from the commercially-designated CT58 engines.
We agree, and have made these changes in the final rule, which includes surplus military models T58-GE-5, T58-GE-10, -100, and -402.
Request To Change the Unsafe Condition Description
GE requests that we change the unsafe condition description of “We are issuing this AD to prevent low cycle fatigue (LCF) cracking and failure of the stage 1 compressor disk, an uncontained engine failure, and damage to the helicopter” to “We are issuing this AD to prevent low-cycle-fatigue (LCF) cracking of the stage 1 compressor disk.” GE states that they do not consider the condition to be unsafe based on their investigation and analysis of this condition.
We do not agree. We reviewed GE's investigation and engineering analysis data with GE, and concluded there is an unsafe condition that requires an AD. The basis for the unsafe condition description in the proposed AD completes the potential scenario leading to the unsafe condition, should the disk cracking continue to an uncontained disk failure, resulting in damage to the helicopter. Further, our statement of the unsafe condition does not change the compliance requirements of GE Alert Service Bulletin No. 72-A0196. We have made no changes to the AD based on this comment.
Request To Change Wording in the Discussion of the Proposed AD
GE requests that we change some wording in the discussion of the proposed AD from “An investigation by GE revealed that the tangential positioning of the blade dovetail slot resulted in the high-peak stresses.” to “An investigation conducted by GE determined that a defined population of stage 1 compressor disks had non-conforming tangential positioning of the blade dovetail slots, which resulted in high-peak stresses at the disk dovetail slot aft acute corner”. GE did not indicate any justification or reason for the proposed change.
We evaluated the change and determined it does offer a more detailed description and points out a nonconformance. However, this discussion information only appears in the proposed AD and not in the final rule, so we have made no change to the AD based on this comment.
Request To Change Requirements Statement
GE requests that we change the requirements statement from “We are proposing this AD which would require removing certain stage 1 compressor disks from service at or before reaching a reduced LCF life limit of 2,100 hours Start Printed Page 8505TSN or by December 31, 2008, whichever occurs first” to “We are proposing this AD which would require removing certain stage 1 compressor disks from service at or before reaching 2,100 hours TSN or by December 31, 2008, whichever occurs first”. GE states that they recommend compliance with GE Alert Service Bulletin No. 72-A0196. GE also reminds the FAA that the published FAA—approved life limit for P/N 5001T20P01 is 4,000 hours or 9,900 cycles.
We partially agree. GE points out that the published FAA-approved life limit for compressor disks, P/N 5001T20P01, is 4,000 hours or 9,900 cycles, for most of the SN disks with this P/N, while the affected SN population of disks has a reduced life limit of 2,100 hours or December 31, 2008, whichever occurs first. The intent of this AD is to require removing the affected disks that need the reduced life limit because of the nonconformity of those disks. We have changed the requirements statement of this AD to state “This AD requires removing certain stage 1 compressor disks from service at or before reaching a reduced LCF life limit for those affected disks of 2,100 hours TSN or by December 31, 2008, whichever occurs first”.
We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting 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
There are about 320 GE CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and -402 series turboshaft engines of the affected design in the worldwide fleet. We estimate that 30 engines installed on helicopters of U.S. registry will be affected by this AD. The action does not impose any additional labor costs. A new disk would cost about $7,965 per engine. We estimate that the prorated cost of the life reduction will be about $4,181 per engine. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $125,430.
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.
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 by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-NE-59-AD” in your request.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
Adoption of the AmendmentStart Amendment Part
Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amendsEnd Amendment Part Start Part
PART 39—AIRWORTHINESS DIRECTIVESEnd Part Start Amendment Part
1. The authority citation for part 39 continues to read as follows:End Amendment Part
2. The FAA amends § 39.13 by adding the following new airworthiness directive:End Amendment Part
2005-04-10 General Electric Company: Amendment 39-13982. Docket No. 2003-NE-59-AD.
(a) This airworthiness directive (AD) becomes effective March 29, 2005.
(c) This AD applies to General Electric Company (GE) CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and “402 turboshaft engines with stage 1 compressor disks, part number (P/N) 5001T20P01, that have a serial number (SN) listed in the following Table 1:
Table 1-Stage 1 Compressor Disk SNs Affected By This AD
GATH8A5M Start Printed Page 8506
GATH6CED Start Printed Page 8507
These engines are installed on, but not limited to, Agusta S.p.A AS-61N, AS-61N1, Sikorsky S-61L, S-61N, S-61R, and S-61NM helicopters, and the following surplus military helicopters that have been certified in accordance with sections 21.25 or 21.27 of the Federal Aviation Regulations (14 CFR 21.25 or 21.27): Sikorsky S-61D and S-61V, Glacier CH-3E, Siller CH-3E and SH-3A, and Robinson Crane CH-3C, CH-3E, HH-3C, HH-3E, and Carson S-61L helicopters.
(d) This AD results from two reports of low blade tip clearances in the compressor. We are issuing this AD to prevent low-cycle-fatigue (LCF) cracking and failure of the stage 1 compressor disk, an uncontained engine failure, and damage to the helicopter.
(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.
Replacement of Stage 1 Compressor Disks
(f) If you have a stage 1 compressor disk, P/N 5001T20P01, with a SN listed in Table 1 of this AD, replace that stage 1 compressor disk at or before reaching a reduced LCF life limit for those affected disks of 2,100 hours time-since-new (TSN) or by December 31, 2008, whichever occurs first. GE Alert Service Bulletin (ASB) No. CT58 S/B 72-A0196, dated July 24, 2003, contains information on replacing the stage 1 compressor disk.
(g) After the effective date of this AD, do not install any stage 1 compressor disk, P/N 5001T20P01, that has a SN listed in Table 1 of this AD and has 2,100 hours TSN or more, into any engine.
Alternative Methods of Compliance
(h) 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.
Material Incorporated by Reference
(j) GE Alert Service Bulletin No. CT58 S/B 72-A0196, dated July 24, 2003, pertains to the subject of this AD.Start Signature
Issued in Burlington, Massachusetts, on February 10, 2005.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. 05-3190 Filed 2-18-05; 8:45 am]
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