Airworthiness Directives; General Electric Company CT58 Series and Surplus Military T58 Series Turboshaft Engines

[Federal Register Volume 70, Number 34 (Tuesday, February 22, 2005)]
[Rules and Regulations]
[Pages 8504-8507]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-3190]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NE-59-AD; Amendment 39-13982; AD 2005-04-10]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT58 Series 
and Surplus Military T58 Series Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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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 (513) 552-3272; fax 
(513) 552-3329, e-mail [email protected], 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 781-238-7181; fax 781-238-7199.

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

[[Page 8505]]

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

0
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

0
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]

0
2. The FAA amends Sec.  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

[[Page 8506]]

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

[[Page 8507]]

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.
[FR Doc. 05-3190 Filed 2-18-05; 8:45 am]
BILLING CODE 4910-13-P

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