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Proposed Rule

Airworthiness Directives; Pratt & Whitney (PW) JT9D-7R4 Series Turbofan Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble Start Printed Page 4964

AGENCY:

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

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

This supplemental NPRM revises an earlier proposed airworthiness directive (AD) for PW JT9D-7R4G2 series turbofan engines. That proposed AD would have required replacing the old configuration 2nd stage high pressure turbine (HPT) air seal assembly with a new design 2nd stage HPT air seal assembly that increases cooling air flow. That proposed AD resulted from a report of an uncontained failure of the 2nd stage HPT air seal assembly, caused by the air seal assembly brace disengaging from the air seal, due to insufficient cooling air flow. This supplemental NPRM revises the proposed AD by proposing to include additional models of the PW JT9D-7R4 turbofan engines in the applicability, requiring a visual and a fluorescent penetrant inspection of the air seal assembly, replacing the 2nd stage HPT vane assemblies, and reopening the comment period. This NPRM results from comments to the proposed AD. We are proposing this AD to prevent uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by April 3, 2007.

ADDRESSES:

Use one of the following addresses to comment 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: (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.

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.

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

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Mark Riley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone (781) 238-7758, fax (781) 238-7199.

End Further Info End Preamble Start Supplemental Information

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-2006-23742; Directorate Identifier 2005-NE-53-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://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 DOT 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 proposal, any comments received and, any final disposition in person at the DOT 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 Docket Management Facility receives them.

Discussion

On April 19, 2006, we issued a proposal to amend part 39 of the Code of Federal Regulations (14 CFR part 39) to add an AD, applicable to PW JT9D-7R4G2 turbofan engines. The proposed AD published as an NPRM in the Federal Register on April 26, 2006 (71 FR 24613). That NPRM would have required at the next HPT module overhaul, replacing the 2nd stage HPT air seal assembly, P/N 815097, with a new configuration 2nd stage HPT air seal assembly that increases cooling air flow, either by installing a new 2nd stage air seal assembly or modifying the old configuration 2nd stage seal assembly. That NPRM resulted from two reports of failure of the 2nd stage HPT air seal assembly, part number (P/N) 815097, installed in JT9D-7R4G2 turbofan engines. That condition, if not corrected, could result in uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane.

Since we issued that NPRM, we received comments to add additional models of the PW JT9D-7R4 series turbofan engines to the applicability for this proposed AD. Also, even though we added new engine models, our changes to the required actions reduced the number of engines that are affected and Start Printed Page 4965the total cost of this proposed AD to the U.S. registered fleet.

Since this change expands the scope of the originally proposed rule, we determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Comments

We provided the public the opportunity to participate in the development of this proposed AD. We have considered the comments received.

Request to Expand the Applicability

Two commenters, Pratt & Whitney and FedEx, ask us to expand the applicability to include the JT9D-7R4E1, -7R4E4, and -7R4H1. The commenters point out that the additional engine models are specified in PW Alert Service Bulletin (ASB) JT9D-7R4-A72-596, dated September 15, 2005. We agree. We added the JT9D-7R4E1, -7R4E4, and -7R4H4 engine models to the applicability for this proposed AD.

Requests for Changes to the Costs of Compliance

One commenter, FedEx, ask us to revise the Costs of Compliance to include the expanded number of engines from adding the additional JT9D-7R4 engine models. The commenter states that the existing Economic impact analysis for the proposed AD considered only the JT9D-7R4G2 engine model.

We agree. We revised the Costs of Compliance section to include all affected JT9D-7R4 engine models. However, updated information from the engine manufacturer confirmed that the number of engines affected actually decreased, which results in reduced cost to the operators.

The same commenter asks us to include the cost of material required to incorporate. The commenter estimates that material cost as $18,000 per engine.

We do not agree. We provide an estimated material cost of $5,400 per engine in the Costs of Compliance in the proposed AD. Parts include new 2nd stage HPT vane covers, P/N 822734, and rivets, P/N ST1219-213, that are required to modify the 2nd stage HPT vane cluster assemblies as specified in ASB JT9D-7R4-A72-596.

One commenter, Northwest Airlines, states the Cost of Compliance in the proposed AD is understated. The commenter states that the Costs of Compliance should include the cost to repair the honeycomb air seal land that is riveted to the 2nd stage vane clusters, which typically require restoring to maintain rotating knife edge-to-seal land clearances. The commenter states the FAA should include the maintenance and repair costs incurred when exposing the parts.

We don't agree. The Costs of Compliance in the proposed AD doesn't include costs associated with parts that require replacement or repair due to typical wear or damage.

Request to Use a Shorter Rivet in the 2nd Stage Scaling Ring Assembly

One commenter, Japan Air Lines, asks that we allow using a shorter rivet, part number (P/N) ST1219-212, instead of rivet, P/N ST12199-213, for the 2nd stage turbine air sealing ring segment assembly, P/N 795187, when incorporating SB JT9D-7R4-A72-596. Japan Air Lines states that PW has approved using the shorter rivet with air sealing ring segment assembly 795187.

We partially agree. Because we are now proposing only to require removing the reduced air flow 2nd stage HPT vane assemblies, P/Ns 797282, 796972, 800082, 800072, 803182, 803282, and 822582, and we don't propose to require modifying the vane assemblies, the commenter can use the shorter rivet approved by PW. We don't need to approve it as an alternative method of compliance.

Request to Change the Compliance Time

One commenter, Northwest Airlines, asks us to change the compliance time from the next exposure of the HPT module to next exposure of the 2nd stage HPT vanes. The commenter states that changing the definition would align the compliance time with the definition of next exposure.

We don't agree. The intent of the proposed AD is to require inspecting the HPT 2nd stage HPT air seal and removing the reduced cooling flow 2nd stage HPT vane assemblies when the HPT module is exposed. The HPT module is exposed when the 1st or 2nd stage HPT rotors are removed from the HPT module assembly, not when the 2nd stage HPT vane assemblies are removed from the HPT case.

Request to Remove or Change Paragraph (d) of the Proposed AD

One commenter, Northwest Airlines, asks that we remove or change paragraph (d) of the proposed AD. The commenter states that as written, the paragraph requires reidentifying the next higher assembly, HPT case assembly, based on P/Ns installed in the module. The commenter states that including the P/N configuration of the top level assembly is not necessary.

We agree. We removed the requirement to use PW ASB JT9D-7R4-A72-596 to replace the vane assembly.

Relevant Service Information

We have reviewed and approved the technical contents of PW Alert Service Bulletin JT9D-7R4-A72-596, dated September 15, 2005. That Alert Service Bulletin describes procedures for replacing 2nd stage HPT air seal assembly, P/N 815097, with a new configuration 2nd stage HPT air seal assembly that increases cooling air flow, either by installing a new 2nd stage air seal assembly or modifying the old configuration 2nd stage HPT seal assembly.

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 at the next HPT module exposure:

  • Visual and fluorescent penetrant inspections of the 2nd stage HPT air seal assembly, P/N 815097, and
  • Removing the reduced cooling flow 2nd stage HPT vane assemblies.

Costs of Compliance

We estimate that this proposed AD would affect 85 PW JT9D-7R4 series turbofan engines installed on airplanes U.S. registry. We also estimate that it would take about 65.5 work-hours per engine to perform the proposed actions, and that the average labor rate is $80 per work-hour. Required parts would cost about $5,400 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $904,400.

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 Start Printed Page 4966that 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 regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

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:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

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

Start Authority

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

End Authority
[Amended]

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

Pratt & Whitney: Docket No. FAA-2006-23742; Directorate Identifier 2006-NE-39-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by April 3, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Pratt & Whitney (PW) JT9D-74R4E1, -74R4E4, -74R4G2, and -74R4H1 turbofan engines. These engines are installed on, but not limited to, Boeing 747-200B, -200C, -200F, and -300 airplanes.

Unsafe Condition

(d) This AD results from a report of an uncontained failure of the 2nd stage high pressure turbine (HPT) air seal assembly, caused by the air seal assembly brace disengaging from the air seal, due to insufficient cooling air flow. We are issuing this AD to prevent uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed at the next HPT module exposure after the effective date of this AD, unless the actions have already been done.

(f) At the next HPT module exposure, perform a visual inspection and a fluorescent penetrant inspection of the 2nd stage HPT air seal assembly part number (P/N) 815097. Use the engine maintenance manual to perform the inspections.

(g) At the next HPT module exposure, remove reduced cooling flow 2nd stage HPT vane assemblies P/Ns 797282, 796972, 800082, 800072, 803182, 803182, 803282, and 822582. Pratt & Whitney Alert Service Bulletin JT9D-7R4-A72-596, dated September 15, 2005, contains information for modifying the reduced cooling flow 2nd stage HPT vane assemblies.

Definition

(h) The manufacturer defines an HPT module exposure as removing the 1st stage HPT rotor and 2nd stage HPT rotor from the HPT case.

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) Pratt & Whitney Alert Service Bulletin JT9D-7R4-A72-596, dated September 15, 2005, contains information for modifying the reduced cooling flow 2nd stage HPT vane assemblies.

Start Signature

Issued in Burlington, Massachusetts, on January 26, 2007.

Peter A. White,

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

End Signature End Part End Supplemental Information

[FR Doc. E7-1707 Filed 2-1-07; 8:45 am]

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