Document ID: FAA-2008-0808-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; General Electric Company (GE) CT58 Series Turboshaft Engines
Posted Date: 2008-07-23T04:00Z

[Federal Register: July 23, 2008 (Volume 73, Number 142)]
[Proposed Rules]               
[Page 42724-42725]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23jy08-14]                         

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Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

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[[Page 42724]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0808; Directorate Identifier 2008-NE-18-AD]
RIN 2120-AA64

 
Airworthiness Directives; General Electric Company (GE) CT58 
Series Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain GE CT58 series turboshaft engines. This proposed AD would 
require recalculating the lives of certain part numbered compressor 
spools using a new repetitive heavy lift (RHL) multiplying factor. This 
proposed AD results from reports of cracks originating from the inner 
faces of the locking screw holes in the compressor spool. We are 
proposing this AD to prevent cracks due to RHL missions. Cracks could 
result in an uncontained rotor burst and damage to, or loss of, the 
helicopter and serious injuries to any person onboard.

DATES: We must receive any comments on this proposed AD by September 
22, 2008.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     Federal eRulemaking Portal: Go to http://
www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.
    You can get the service information identified in this proposed AD 
from 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.csc@ae.ge.com.

FOR FURTHER INFORMATION CONTACT: Christopher J. Richards, Aerospace 
Engineer, Engine Certification Office, FAA, Engine & Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803; e-
mail: christopher.j.richards@faa.gov; telephone (781) 238-7133; fax 
(781) 238-7199.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send us any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2008-0808; Directorate 
Identifier 2008-NE-18-AD'' in the subject line of your comments. We 
specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of the proposed AD. We will consider 
all comments received by the closing date and may amend the proposed AD 
in light of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact 
with FAA personnel concerning this proposed AD. Using the search 
function of the Web site, anyone can find and read the comments in any 
of our dockets, including, if provided, the name of the individual who 
sent the comment (or signed the comment on behalf of an association, 
business, labor union, etc.). You may review the DOT's complete Privacy 
Act Statement in the Federal Register published on April 11, 2000 (65 
FR 19477-78).

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Operations office (telephone (800) 647-5527) is 
the same as the Mail address provided in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

Discussion

    We have received reports of nine compressor spools, with cracks 
originating from the inner faces of the locking screw holes in 
compressor spools used in RHL missions. We have not received any 
reports of in-flight events occurring because of the cracking. GE, the 
engine manufacturer, has developed a new RHL multiplying factor for use 
when calculating compressor spool lives on engines used for RHL 
missions. The new, larger multipliers will prevent the cracks from 
propagating to failure by causing the spools to meet their service life 
limits sooner, resulting in earlier removal from the engine. This 
condition, if not corrected, could result in an uncontained rotor burst 
and damage to, or loss of, the helicopter and serious injuries to any 
person onboard.

Relevant Service Information

    We have reviewed and approved the technical contents of GE Alert 
Service Bulletin (ASB) CT58 S/B 72-A0162, Revision 12, dated April 17, 
2008, that describes procedures for calculating the compressor spool 
cycles using RHL mission multipliers.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other products 
of this same type design. We are proposing this AD which would require 
recalculating the cycles on certain compressor spools using new RHL 
mission multipliers within 30 days after the effective date of the 
proposed AD.

Costs of Compliance

    We estimate that this proposed AD would affect 89 engines installed 
on helicopters of U.S. registry. We also estimate that it would take 
about 0.5 work-hour per engine to perform the proposed actions, and 
that the average labor rate is $80 per work-hour. Prorated life lost 
for the compressor spools

[[Page 42725]]

would cost about $16,972 per engine. Based on these figures, we 
estimate the total cost of the proposed AD to U.S. operators to be 
$1,514,068.

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 proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 the proposed AD:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Would 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 regulatory evaluation of the estimated costs to 
comply with this proposed AD. 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, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration proposes to amend 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.

Sec.  39.13  [Amended]

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

General Electric Company (GE): Docket No. FAA-2008-0808; Directorate 
Identifier 2008-NE-18-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by September 
22, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to GE CT58 series turboshaft engines with a 
compressor spool, part number (P/N) 5920T82G07, 6010T57G07, or 
6010T57G08, installed. These engines are installed on, but not 
limited to, Sikorsky S-61A, S-61L, S-61N, S-61R, S-62, and Columbia 
107-II helicopters.

Unsafe Condition

    (d) This AD results from reports of cracks originating from the 
inner faces of the locking screw holes in the compressor spool. We 
are issuing this AD to prevent cracks due to repetitive heavy lift 
(RHL) missions. Cracks could result in an uncontained rotor burst 
and damage to, or loss of, the helicopter and serious injuries to 
any person onboard.

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.

Recalculating Compressor Spool Cycles

    (f) Within 30 days after the effective date of this AD, 
recalculate the life of compressor spools, P/N 5920T82G07, 
6010T57G07, or 6010T57G08, using an RHL mission multiplying factor 
of both 3.7 cycles per hour and 6.0 cycles per hour. GE Alert 
Service Bulletin CT58 S/B 72-A0162, Revision 12, dated April 17, 
2008, contains information on calculating life cycles for the 
compressor spools.

Removing Compressor Spools Based on the New Recalculated Cycles

    (g) Before January 1, 2010, remove the compressor spools, P/N 
5920T82G07, 6010T57G07, or 6010T57G08, at the earlier of when:
    (1) The compressor spool reaches its part life limit as 
calculated using an RHL multiplying factor of 3.7, or
    (2) You can see the spool at shop visit after it has reached its 
part life limit using an RHL multiplying factor of 6.0.
    (h) On January 1, 2010 and thereafter, remove the engine before 
the compressor spool exceeds its part life limit as calculated using 
an RHL multiplying factor of 6.0.
    (i) As of January 1, 2010, don't use an RHL multiplying factor 
of 3.7 to calculate the life of the compressor spool.

Installation Prohibition

    (j) After the effective date of this AD, don't install any 
engine that has a compressor spool installed that meets or exceeds 
the life limits as calculated in paragraph (g)(1) through (g)(2) or 
(h) of this AD.

Alternative Methods of Compliance

    (k) 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

    (l) GE Alert Service Bulletin CT58 S/B 72-A0162, Revision 12, 
dated April 17, 2008, pertains to the subject of this AD.
    (m) Contact Christopher J. Richards, Aerospace Engineer, Engine 
Certification Office, FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803; e-mail: 
christopher.j.richards@faa.gov; telephone (781) 238-7133; fax (781) 
238-7199, for more information about this AD.

    Issued in Burlington, Massachusetts, on July 17, 2008.
Marc Bouthillier,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
 [FR Doc. E8-16883 Filed 7-22-08; 8:45 am]

BILLING CODE 4910-13-P