Airworthiness Directives; General Electric Company CT64-820-4 Turboprop Engines

[Federal Register Volume 70, Number 118 (Tuesday, June 21, 2005)]
[Rules and Regulations]
[Pages 35523-35525]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-12173]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21586; Directorate Identifier 2005-NE-16-AD; 
Amendment 39-14148; AD 2005-13-11]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT64-820-4 
Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
General Electric Company (GE) CT64-820-4 turboprop engines with stage 1 
turbine disk and shaft, part number (P/N) 6004T47P03 or 4921T10P02 
installed. This AD requires removing from service these stage 1 turbine 
disk and shafts at reduced compliance times. This AD results from the 
discovery by the manufacturer of low-cycle-fatigue (LCF) cracks found 
in stage 1 turbine disk and shafts, P/Ns 6004T47P03 and 4921T10P02. We 
are issuing this AD to prevent uncontained failure of the stage 1 
turbine disk and shaft, resulting in damage to the airplane.

DATES: This AD becomes effective July 6, 2005.
    We must receive any comments on this AD by August 22, 2005.

ADDRESSES: Use one of the following addresses to comment on this AD:
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    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 address: [email protected], for the service 
information identified in this AD.

[[Page 35524]]


FOR FURTHER INFORMATION CONTACT: Anthony W. Cerra Jr., Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone 781-238-7128; fax 781-238-7199; e-mail address: 
[email protected].

SUPPLEMENTARY INFORMATION: GE has informed us that cracks have been 
found in some retired stage 1 disk and shafts which were removed from 
military T64 engines and are equivalent to the CT64-820-4 P/Ns 
6004T47P03 and 4921T10P02. The cracks were located at ``small feature'' 
locations. A ``small feature'' location is any rotating hardware 
feature with drawing radii less than 0.020-inch, that could become 
potentially life limiting. These cracks were difficult to find due to 
the nature of their geometry and location on the part. The cracks were 
confirmed upon metallurgical evaluation of cut-up sections of those 
parts. This condition, if not corrected, could result in an uncontained 
failure of the stage 1 turbine disk and shaft, resulting in damage to 
the airplane.
    GE is aware of about 50 engines that are in service. Three of these 
engines have the affected parts. GE has coordinated the compliance plan 
with the operator of these three certain serial number engines. The 
specific compliance times for these engines minimize adverse operator 
impact, yet maintain the interests of safety. GE is aware of 
approximately 90 additional engines for which GE does not know if the 
engines are in service or if they have the affected parts. GE has 
established the additional removal-from-service compliance times for 
these other engines in the event that any are still in service. We are 
using GE's compliance times in this AD.

FAA's Determination and Requirements of This AD

    Although no airplanes that are registered in the United States use 
these engines, the possibility exists that the engines could be used on 
airplanes that are registered in the United States in the future. The 
unsafe condition described previously is likely to exist or develop on 
other CT64-820-4 turboprop engines of the same type design. We are 
issuing this AD to prevent uncontained failure of the stage 1 turbine 
disk and shaft, resulting in damage to the airplane. This AD requires 
removing from service stage 1 turbine disk and shafts, P/Ns 6004T47P03 
and 4921T10P02 at reduced compliance times.

FAA's Determination of the Effective Date

    Since there are currently no domestic operators of this engine 
model, notice and opportunity for public comment before issuing this AD 
are unnecessary. A situation exists that allows the immediate adoption 
of this regulation.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety and was not preceded by notice and an opportunity for public 
comment; however, we invite you to send us any written relevant data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``AD Docket No. FAA-2005-21586; 
Directorate Identifier 2005-NE-16-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify it.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this AD. Using the search function of the DMS Web 
site, anyone can find and read the comments in any of our dockets, 
including 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) or you may visit 
http://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the AD, any comments 
received, and any final disposition in person at the DMS Docket Offices 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the DMS receives them.

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 the regulation:
    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. 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 at the 
address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

0
Under the authority delegated to me by the Administrator, the Federal 
Aviation Administration amends part 39 of the Federal Aviation 
Regulations (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:

2005-13-11 General Electric Company: Amendment 39-14148. Docket No. 
FAA-2005-21586; Directorate Identifier 2005-NE-16-AD.

[[Page 35525]]

Effective Date

    (a) This airworthiness directive (AD) becomes effective July 6, 
2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to General Electric Company (GE) CT64-820-4 
turboprop engines with stage 1 turbine disk and shaft, part number 
(P/N) 6004T47P03 or 4921T10P02 installed. These engines are 
installed on, but not limited to, DeHavilland DHC-5D Buffalo 
airplanes.

Unsafe Condition

    (d) This AD results from the discovery by the manufacturer of 
low-cycle fatigue (LCF) cracks found in stage 1 turbine disk and 
shafts, P/Ns 6004T47P03 and 4921T10P02. We are issuing this AD to 
prevent uncontained failure of the stage 1 turbine disk and shaft, 
resulting in damage to the airplane.

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.

Engine Serial Numbers (SNs) 268537, 268565, and 268637

    (f) For engine serial number (SN) 268537, remove the stage 1 
turbine disk and shaft from service at or before accumulating 1,700 
cycles-since-new (CSN), or by December 31, 2005, whichever occurs 
first.
    (g) For engine SN 268565, remove the stage 1 turbine disk and 
shaft from service at or before accumulating 1,585 CSN, or by 
December 31, 2005, whichever occurs first.
    (h) For engine SN 268637, remove the stage 1 turbine disk and 
shaft from service at or before accumulating 1,345 CSN, or by 
December 31, 2005, whichever occurs first.

All Other Engines

    (i) For all other engines that have accumulated 590 CSN or more 
on the stage 1 turbine disk and shaft on the effective date of this 
AD, remove stage 1 turbine disk and shaft from service at or before 
accumulating an additional 10 cycles-in-service, at or before 
accumulating the service life limit of 1,700 CSN, or by December 31, 
2005, whichever occurs first.
    (j) For all other engines that have accumulated fewer than 590 
CSN on the stage 1 turbine disk and shaft on the effective date of 
this AD, remove stage 1 turbine disk and shaft from service at the 
next piece-part-exposure, or before accumulating 600 CSN, or by 
December 31, 2005, whichever occurs first.
    (k) After the effective date of this AD, do not install any 
stage 1 turbine disk and shaft, P/N 6004T47P03 or 4921T10P02, into 
any engine.
    (l) After the effective date of this AD, do not install any 
engine with stage 1 turbine disk and shaft, P/N 6004T47P03 or 
4921T10P02, into any airplane.

Definition

    (m) For the purpose of this AD, piece-part exposure is defined 
as the stage 1 disk and shaft is completely disassembled using the 
disassembly instructions of the manufacturer's engine manual, or 
other FAA-approved engine manual.

Alternative Methods of Compliance

    (n) 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

    (o) Information on determining engine usage in cycles for 
comparison to CT64 service life limits can be found in GE Service 
Bulletin CEB No. 93, Revision 2, dated May 30, 1984. GE Alert 
Service Bulletin No. CT64 S/B 72-A0113, Revision 1, dated May 16, 
2005, also pertains to the subject of this AD.

Material Incorporated by Reference

    (p) None.

    Issued in Burlington, Massachusetts, on June 14, 2005.
Robert Ganley,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 05-12173 Filed 6-20-05; 8:45 am]
BILLING CODE 4910-13-P

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