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Proposed Rule

Airworthiness Directives; Pratt & Whitney (PW) JT9D-7 Series Turbofan Engines

Document Details

Information about this document as published in the Federal Register.

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AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for PW models JT9D-7, -7A, -7AH, -7H, -7F, and -7J turbofan engines. This proposed AD would require initial and repetitive borescope inspections of the 2nd stage high-pressure turbine (HPT) rotor and stator assembly. This proposed AD results from an uncontained failure of a 2nd stage HPT rotor disk that caused the engine to separate from the airplane. We are proposing this AD to prevent failure of the 2nd stage HPT rotor disk, which could result in uncontained engine failure, damage to the airplane, and the engine separating from the airplane.

DATES:

We must receive any comments on this proposed AD by September 8, 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 Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone (860) 565-8770; fax (860) 565-4503.

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FOR FURTHER INFORMATION CONTACT:

Mark Riley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: mark.riley@faa.gov; telephone (781) 238-7758, fax (781) 238-7199.

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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-2008-0759; Directorate Identifier 2008-NE-02-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

On October 20, 2004, a PW JT9D-7A engine experienced an uncontained failure of the 2nd stage HPT rotor disk. The resulting imbalance caused the engine to separate from the airplane. Root cause investigation revealed that improper assembly caused the 2nd stage HPT vane assemblies to lean back into the 2nd stage HPT rotor disk. The investigation found indications of three improper assembly steps within the engine that contributed to this vane lean back, disk fracture, uncontained event.

  • First, the investigation found an improper silver-based antigallant.
  • Second, the lock wire on the 2nd stage HPT vane retaining bolts was not applied correctly.
  • Finally, the 2nd stage HPT vane retaining bolts were reused.
  • Pratt & Whitney determined that the assembly procedures in the engine manual (EM) might be misinterpreted and issued new procedures to ensure the repair facilities follow proper assembly procedures. Because PW was unable to determine the time frame over which the repair facility used the old assembly procedures, they developed a borescope inspection to identify vane lean back of the 2nd stage HPT vanes of all JT9D-7 series engines. This condition, if not corrected, could result in uncontained engine failure, damage to the airplane, and the engine separating from the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) JT9D A6488, Revision 1, dated April 18, 2008, that describes the procedures and inspection requirements for borescope inspection of the 2nd stage HPT vanes.

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 an initial and repetitive borescope inspection of the Start Printed Page 396282nd stage HPT vane assembly. The proposed AD would require you to use the service information described previously to perform these actions.

Interim Action

These actions are interim actions and we may take further rulemaking actions in the future.

Costs of Compliance

We estimate that this proposed AD would affect 240 engines installed on airplanes of U.S. registry. We also estimate that it would take about 5 work-hours per engine to perform the proposed actions, that each engine might require two inspections, and that the average labor rate is $80 per work-hour. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $192,000.

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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

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

Pratt & Whitney: Docket No. FAA-2008-0759; Directorate Identifier 2008-NE-02-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by September 8, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Pratt & Whitney (PW) JT9D-7, -7A, -7AH, -7H, -7F, and -7J turbofan engines. These engines are installed on, but not limited to, Boeing 747 series airplanes.

Unsafe Condition

(d) This AD results from an uncontained failure of a 2nd stage high-pressure turbine (HPT) rotor disk that caused the engine to separate from the airplane. We are issuing this AD to prevent failure of the 2nd stage HPT rotor disk, which could result in uncontained engine failure, damage to the airplane, and the engine separating from 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.

Initial Borescope Inspection

(f) Within 100 cycles-in-service (CIS) after the effective date of this AD, or within 1,000 CIS after the last HPT module overhaul, whichever occurs later, do the following:

(1) Use the Accomplishment Instructions of PW Alert Service Bulletin (ASB) JT9D A6488, Revision 1, dated April 18, 2008, to borescope-inspect the 2nd stage HPT rotor and stator assembly either on-wing or in the shop.

(2) If you see any damage or contact between the 2nd stage HPT vanes and the 2nd stage HPT rotor, remove the engine from service.

Repetitive Borescope Inspection

(g) Thereafter, within 1,000 cycles-since-last inspection, do the following:

(1) Use the Accomplishment Instructions of PW ASB JT9D A6488 Revision 1, dated April 18, 2008, to borescope-inspect the 2nd stage HPT rotor and stator assembly either on-wing or in the shop.

(2) If you see any damage or contact between the 2nd stage HPT vanes and the 2nd stage HPT rotor, remove the engine from service.

Optional Terminating Action

(h) Installing the 2nd stage HPT vanes as specified in the JT9D-7 Engine Manual Revision 122, dated February 15, 2008, terminates the repetitive inspection requirement specified in paragraph (g) of this AD.

Alternative Methods of Compliance

(i) 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

(j) PW ASB JT9D A6488, Revision 1, dated April 18, 2008, pertains to the subject of this AD.

(k) Contact Mark Riley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: mark.riley@faa.gov; telephone (781) 238-7758; fax (781) 238-7199, for more information about this AD.

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Issued in Burlington, Massachusetts, on July 3, 2008.

Diane Cook,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

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[FR Doc. E8-15682 Filed 7-9-08; 8:45 am]

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