05-3190. Airworthiness Directives; General Electric Company CT58 Series and Surplus Military T58 Series Turboshaft Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

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.

DATES:

This AD becomes effective March 29, 2005.

ADDRESSES:

Contact GE Aircraft Engines Customer Support Center, M/D 285, 1 Neumann Way, Evendale, OH 45215, telephone [phone]; fax [phone], e-mail [e-mail], 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.

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 [phone]; fax [phone].

SUPPLEMENTARY 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.

Comments

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 TSN 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”.

Conclusion

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.

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 by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-NE-59-AD” in your request.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• 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 39—AIRWORTHINESS DIRECTIVES

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

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

2005-04-10  General Electric Company: Amendment 39-13982. Docket No. 2003-NE-59-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective March 29, 2005.

Affected ADs

(b) None.

Applicability

(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

GATD0PD2

GATH6RWW

GATH7PR0

GATH86K2

GATH8K0P

GATD0PD3

GATH6T00

GATH7PR1

GATH86K3

GATH8K0R

GATD0PD5

GATH6T01

GATH7PR2

GATH86K4

GATH8K0T

GATD0PD6

GATH6T02

GATH7PR3

GATH86K5

GATH8K0W

GATD0PD7

GATH6T03

GATH7PR4

GATH8A5G

GATH8K12

GATD0PD8

GATH6T04

GATH7PR5

GATH8A5H

GATH8K13

GATD0PD9

GATH6T05

GATH7PR6

GATH8A5J

GATH8K14

GATD0PDA

GATH7K4K

GATH7PR7

GATH8A5K

GATH8K15

GATD0PDC

GATH7K4L

GATH7PR8

GATH8A5L

GATH8K16

GATH53GC

GATH7K4M

GATH7PR9

GATH8A5M

GATH8K17

GATH53GD

GATH7K4N

GATH7PRA

GATH8A5N

GATH8K18

GATH53GE

GATH7K4P

GATH7PRC

GATH8A5P

GATH8K19

GATH53GF

GATH7K4R

GATH7PRD

GATH8A5T

GATH8W7H

GATH53GH

GATH7K4T

GATH7PRE

GATH8A5W

GATH8W7J

GATH53GJ

GATH7K5G

GATH7PRF

GATH8A60

GATH8W7L

GATH53GK

GATH7KGH

GATH7PRG

GATH8A61

GATH8W7M

GATH5T70

GATH7KGK

GATH7PRH

GATH8A62

GATH8W7N

GATH5T71

GATH7KGL

GATH7PRJ

GATH8A63

GATH8W7P

GATH5T72

GATH7KGM

GATH7PRK

GATH8A64

GATH8W7R

GATH5T73

GATH7KGN

GATH7PRL

GATH8A66

GATH8W7T

GATH5T74

GATH7KGP

GATH7PRM

GATH8A67

GATH8WD4

GATH5T75

GATH7KGR

GATH7PRN

GATH8A68

GATH8WD5

GATH5T76

GATH7KGT

GATH7PRP

GATH8GRG

GATH8WD6

GATH5T77

GATH7KGW

GATH7PRR

GATH8GRH

GATH8WD7

GATH5T78

GATH7KH0

GATH7PRT

GATH8GRK

GATH8WD8

GATH5T79

GATH7KH1

GATH7PRW

GATH8GRL

GATH8WD9

GATH5T7A

GATH7KH2

GATH7PT0

GATH8GRM

GATH8WDA

GATH5T7C

GATH7LAL

GATH7RTP

GATH8GRN

GATH8WDC

GATH5T7D

GATH7LAM

GATH7RTR

GATH8GRP

GATH8WDD

GATH5T7E

GATH7LAN

GATH7RTT

GATH8GRR

GATH8WDE

GATH5T7F

GATH7LAP

GATH82R8

GATH8GRT

GATH8WDF

GATH5T7G

GATH7LAR

GATH82R9

GATH8GRW

GATH8WDG

GATH5T7H

GATH7LAT

GATH82RA

GATH8GT0

GATH8WDH

GATH6CDL

GATH7LAW

GATH82RD

GATH8GT1

GATH8WDJ

GATH6CDM

GATH7LC0

GATH82RE

GATH8GT3

GATH8WDK

GATH6CDN

GATH7LC1

GATH82RF

GATH8GT5

GATH8WDL

GATH6CDP

GATH7LC2

GATH82RG

GATH8GT7

GATH94R3

GATH6CDR

GATH7LC3

GATH82RH

GATH8GT8

GATH94R4

GATH6CDT

GATH7LC4

GATH82RJ

GATH8HGF

GATH94R6

GATH6CE0

GATH7LC5

GATH82RK

GATH8HGG

GATH94R7

GATH6CE1

GATH7LC6

GATH82RL

GATH8HGH

GATH94R8

GATH6CE2

GATH7LC7

GATH82RM

GATH8HGJ

GATH94R9

GATH6CE3

GATH7LC8

GATH82RN

GATH8HGK

GATH94RA

GATH6CE4

GATH7M8G

GATH82RP

GATH8HGL

GATH94RC

GATH6CE5

GATH7M8H

GATH82RR

GATH8HGM

GATH94RD

GATH6CE6

GATH7M8J

GATH82RT

GATH8HGN

GATH94RE

GATH6CE7

GATH7M8K

GATH82RW

GATH8HGP

GATH94RF

GATH6CE8

GATH7M8L

GATH82T0

GATH8HGR

GATH94RG

GATH6CE9

GATH7M8M

GATH82T1

GATH8HGT

GATH94RJ

GATH6CEA

GATH7M8N

GATH86JD

GATH8HGW

GATH94RK

GATH6CEC

GATH7MLK

GATH86JE

GATH8HH0

GATH94RN

GATH6CED

GATH7MLL

GATH86JF

GATH8HH1

GATH94RP

GATH6CEE

GATH7MLM

GATH86JG

GATH8HH2

GATH94RR

GATH6CEF

GATH7MLN

GATH86JH

GATH8HH3

GATH94RT

GATH6RH8

GATH7MLP

GATH86JJ

GATH8HH4

GATH96HF

GATH6RH9

GATH7MLR

GATH86JK

GATH8HH5

GATH96HG

GATH6RHC

GATH7MLT

GATH86JL

GATH8HH6

GATH96HK

GATH6RHD

GATH7MLW

GATH86JM

GATH8HH7

GATH96HL

GATH6RHE

GATH7MM0

GATH86JN

GATH8K0H

GATH96HM

GATH6RHF

GATH7MM1

GATH86JP

GATH8K0J

GATH96HN

GATH6RHG

GATH7MM2

GATH86JR

GATH8K0K

GATH96HR

GATH6RHH

GATH7MM3

GATH86JT

GATH8K0L

GATH96HT

GATH6RHJ

GATH7PPT

GATH86JW

GATH8K0M

GATH96HW

GATH6RWT

GATH7PPW

GATH86K0

GATH8K0N

GATH96J0

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.

Unsafe Condition

(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.

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.

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

(i) None.

Related Information

(j) GE Alert Service Bulletin No. CT58 S/B 72-A0196, dated July 24, 2003, pertains to the subject of this AD.

Issued in Burlington, Massachusetts, on February 10, 2005.

Francis A. Favara,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.