04-17755. Airworthiness Directives; General Electric Company (GE); CT7-2D1 Turboshaft Engines.

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for GE CT7-2D1 turboshaft engines. This AD requires replacing certain turbine stage 2 aft cooling plates, part number (P/N) 6064T0P02. This AD results from an uncontained failure of a turbine stage 2 aft cooling plate in a GE CT7 turboprop engine. We are issuing this AD to prevent a similar uncontained failure of turbine stage 2 aft cooling plates in GE CT7-2D1 turboshaft engines.

DATES:

This AD becomes effective August 23, 2004.

We must receive any comments on this AD by October 5, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://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 20590-0001.
• Fax: [phone].
• 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.

You may examine the comments on this AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Mark J. Bouyer, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

In July of 1999, an uncontained failure of a turbine stage 2 aft cooling plate occurred on a GE CT7 turboprop engine. An investigation indicated that the electro-discharge (EDM) machining of the cooling airholes caused microcracks in the walls of the airholes that could propagate through the turbine stage 2 cooling plate and result in an uncontained engine failure. We issued AD 2002-01-03 to prevent an uncontained failure of turbine stage 2 aft cooling plates in GE CT7 turboprop engines. In October of 2003, the manufacturer informed us of a similar problem with GE CT7-2D1 turboshaft engines. This AD requires replacing turbine stage 2 aft cooling plates, P/N 6064T07P02, with serial numbers (SNs) GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N. Asterisks represent any subsequent number or letter that follow the root SN. This condition, if not corrected, could result in an uncontained failure of turbine stage 2 aft cooling plates in GE CT7-2D1 turboshaft engines.

FAA's Determination and Requirements of This AD

Although no aircraft that are registered in the United States use these engines, the possibility exists that the engines could be used on aircraft that are registered in the United States in the future. The unsafe condition as previously described in GE CT7 turboprop engines is likely to exist or develop in GE CT7-2D1 turboshaft engines because they are of the same type design. We are issuing this AD to prevent an uncontained failure of turbine stage 2 aft cooling plates in GE CT7-2D1 turboshaft engines. This AD requires replacing turbine stage 2 aft cooling plates, P/N 6064T07P02, with SNs GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N at the next disassembly of the gas generator turbine rotor assembly at an FAA-approved overhaul facility, but not to exceed 5,000 cycles-since-new.

FAA's Determination of the Effective Date

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

Docket Management System (DMS)

We have implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, we posted new AD actions on the DMS and assigned a DMS docket number. We track each action and assign a corresponding Directorate identifier. The DMS docket No. is in the form “Docket No. FAA-200X-XXXXX.” Each DMS docket also lists the Directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

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 submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. FAA-2004-18758; Directorate Identifier 2004-NE-24-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.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.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 [phone]) 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.

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

Adoption of the Amendment

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

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:

2004-16-07. General Electric Company: Amendment 39-13763. Docket No. FAA-2004-18758; Directorate Identifier 2004-NE-24-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective August 23, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) CT7-2D1 turboshaft engines with turbine stage 2 aft cooling plates, part number (P/N) 6064T07P02, and serial numbers (SN) starting with GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N installed. Asterisks represent any subsequent number or letter that follow the root SN. These engines are installed on, but not limited to, Sikorsky S-70 helicopters.

Unsafe Condition

(d) This AD results from an uncontained failure of a turbine stage 2 aft cooling plate in a GE CT7 turboprop engine. We are issuing this AD to prevent a similar uncontained failure of turbine stage 2 aft cooling plates in GE CT7-2D1 turboshaft engines.

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.

Cooling Plate Removal

(f) At the next disassembly of the gas generator turbine rotor assembly at an FAA-approved overhaul facility, but not later than 5,000 cycles-since-new, replace any turbine stage 2 aft cooling plate, P/N 6064T07P02, with SNs starting with GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N, with a cooling plate that does not have a SN specified in this AD.

(g) After the effective date of this AD, do not install stage 2 aft cooling plate, P/N 6064T07P02, SNs GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N into any engine.

Material Incorporated by Reference

(h) None.

Related Information

(i) GE CT7-TS Alert Service Bulletin 72-A0032, dated June 11, 2003, provides additional information regarding the disassembly of the gas generator turbine rotor assembly.

Issued in Burlington, Massachusetts, on July 29, 2004.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.