Airworthiness Directives; General Electric Company CT7-5, -7, and -9 Series Turboprop Engines, 19893-19894 [05-7561]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 72 (Friday, April 15, 2005)]
[Proposed Rules]
[Pages 19893-19894]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-7561]


========================================================================
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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Federal Register / Vol. 70, No. 72 / Friday, April 15, 2005 / 
Proposed Rules

[[Page 19893]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20944; Directorate Identifier 2003-NE-64-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT7-5, -7, and 
-9 Series Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for General Electric Company (GE) CT7-5A2, -5A3, -7A, -7A1, -9B, -9B1, 
and -9B2 turboprop engines, with stage 2 turbine aft cooling plate, 
part number (P/N) 6064T07P01, 6064T07P02, 6064T07P05, or 6068T36P01 
installed. This proposed AD would require a onetime eddy current 
inspection (ECI) of certain P/N stage 2 turbine aft cooling plate 
boltholes. This proposed AD results from reports of six stage 2 turbine 
aft cooling plates found cracked during inspection. We are proposing 
this AD to prevent stage 2 aft cooling plate separation, resulting in 
uncontained engine failure and damage to the airplane.

DATES: We must receive any comments on this proposed AD by June 14, 
2005.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     DOT Docket Web Site: Go to https://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide Rulemaking Web Site: Go to https://
www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-001.
     Fax: (202) 493-2251.
     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 General Electric Aircraft Engines CT7 Series Turboprop 
Engines, 1000 Western Ave., Lynn, MA 01910; telephone (781) 594-3140, 
fax (781) 594-4805, for the service information identified in this 
proposed AD.
    You may examine the comments on this proposed AD in the AD docket 
on the Internet at https://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Eugene Triozzi, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7148; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-20944; 
Directorate Identifier 2003-NE-64-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 https://
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 proposed 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 https://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, 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.

Discussion

    GE advises that they received reports of six stage 2 turbine aft 
cooling plates found cracked at the boltholes. The cracks ran into the 
lower ligament. Investigation has revealed that these cracks resulted 
from using worn balance arbor washers and or worn nuts. The worn arbor 
washers and worn nuts caused bolthole deformation and cracking. This 
cracking could lead to separation of the stage 2 turbine aft cooling 
plate from the engine. GE has analyzed the inspection data from 236 
stage 2 turbine aft cooling plates to establish validated lives for 
lower ligament cracking and breakthrough. GE has also conducted 
analysis to predict lives for top ligament cracking and breakthrough, 
which would lead to cooling plate separation. GE's risk analysis shows 
that a onetime ECI at the next shop visit, but before accumulating an 
additional 6,000 cycles-in-service (CIS) after the effective date of 
the AD, of the affected P/N stage 2 turbine aft cooling plates will 
provide early detection of at-risk parts. GE advises that the 
production and overhaul tools have been removed and inspected to 
identify and replace arbor washers and nuts that are worn. This 
condition, if not corrected, could result in stage 2 aft cooling plate 
separation, resulting in uncontained engine failure and damage to the 
airplane.

Relevant Service Information

    We have reviewed and approved the technical contents of GE Alert 
Service Bulletin (ASB) No. CT7-TP S/B 72-A0464, Revision 2, dated May 
9, 2003, that describes procedures for performing a onetime ECI of 
stage 2 turbine aft cooling plates, P/Ns 6064T07P01, 6064T07P02, 
6064T07P05, and

[[Page 19894]]

6068T36P01, at the next engine or hot section module shop visit.

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 
a onetime ECI of the boltholes of stage 2 turbine aft cooling plates, 
P/Ns 6064T07P01, 6064T07P02, 6064T07P05, and 6068T36P01. The ECI must 
be done at the next engine or hot section module shop visit or before 
accumulating an additional 6,000 CIS after the effective date of the 
AD, whichever occurs first. The proposed AD would require you to use 
the service information described previously to perform these actions.

Costs of Compliance

    There are about 1,240 GE CT7-5, -7, and -9 series turboprop engines 
of the affected design in the worldwide fleet. We estimate that 550 
engines installed on airplanes of U.S. registry would be affected by 
this proposed AD. We also estimate that it would take about one work 
hour per engine to perform the proposed actions, and that the average 
labor rate is $65 per work hour. We estimate that 2.5% (or 14) of the 
550 engines will require stage 2 turbine aft cooling plates being 
rejected by the onetime ECI. Required parts would cost about $17,000 
per engine. Based on these figures, we estimate the total cost of the 
proposed AD to U.S. operators to be $270,700.

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 
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. 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 summary of the costs to comply with this proposal 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.

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: Docket No. FAA-2005-20944; Directorate 
Identifier 2003-NE-64-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by June 14, 
2005.

Affected ADs

    (b) None.
    Applicability: (c) This AD applies to General Electric Company 
(GE) CT7-5A2, -5A3, -7A, -7A1, -9B, -9B1, and -9B2 turboprop 
engines, with stage 2 turbine aft cooling plate, part number (P/N) 
6064T07P01, 6064T07P02, 6064T07P05, or 6068T36P01 installed. These 
engines are installed on, but not limited to, Construcciones 
Aeronauticas, SA CN-235 series and SAAB Aircraft AB SF340 series 
airplanes.

Unsafe Condition

    (d) This AD results from reports of six stage 2 turbine aft 
cooling plates found cracked during inspection.
    Compliance: (e) You are responsible for having the actions 
required by this AD performed at the next engine or hot section 
module shop visit, but before accumulating an additional 6,000 
cycles-in-service after the effective date of the AD, unless already 
done.

OneTime Eddy Current Inspection (ECI)

    (f) Perform a onetime ECI of the stage 2 turbine aft cooling 
plate boltholes, using paragraph 3.B. of GE Alert Service Bulletin 
(ASB) No. CT7-TP S/B 72-A0464, Revision 2, dated May 9, 2003.
    (g) Remove from service any stage 2 turbine aft cooling plate 
that does not pass the return to service criteria specified in 
paragraph 3.B.(2) of GE Alert Service Bulletin (ASB) No. CT7-TP S/B 
72-A0464, Revision 2, dated May 9, 2003.

Previous Credit

    (h) Previous credit is allowed for onetime ECIs of the stage 2 
turbine aft cooling plate boltholes that were done using GE ASB No. 
CT7-TP S/B 72-A0464, dated February 25, 2003, or GE ASB No. CT7-TP 
S/B 72-A0464, Revision 1, dated March 12, 2003, before the effective 
date of this AD.

Definition of Engine or Hot Section Module Shop Visit

    (i) For the purposes of this AD, an engine or hot section module 
shop visit is defined as the introduction of the engine or hot 
section module into a shop that includes separation of CT7 turboprop 
engine major case flanges.

Alternative Methods of Compliance

    (j) 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

    (k) None.

    Issued in Burlington, Massachusetts, on April 11, 2005.
Robert E. Guyotte,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 05-7561 Filed 4-14-05; 8:45 am]
BILLING CODE 4910-13-P