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Airworthiness Directives; Pratt & Whitney JT9D 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.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney JT9D series turbofan engines. This AD will require installation of an improved No. 4 bearing internal oil pressure tube, initial and repetitive inspections of the No. 4 bearing oil pressure tube for turbine exhaust case (TEC) strut clearance and alignment, and, if necessary, replacement with serviceable parts. This amendment is prompted by loss of integrity in the oil system that allows oil to migrate into high temperature metal cavities in the turbine exhaust case and cause oil fires. The actions specified by this AD are intended to prevent oil fires in and around the No. 4 bearing area that could cause excessive thermal growth of the sixth stage low pressure turbine (LPT) disk, liberation of the sixth stage LPT disk, uncontained engine failure, and damage to the airplane.

DATES:

Effective date January 19, 2001. The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of January 19, 2001.

ADDRESSES:

The service information referenced in this AD may be obtained from Pratt & Whitney, 400 Main Street, East Hartford, CT 06108; telephone: (860) 565-6600, fax: (860) 565-4503. This information may be examined at the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

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FOR FURTHER INFORMATION CONTACT:

Chris Gavriel, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone: (781) 238-7147, fax: (781) 238-7199.

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SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) applicable to Pratt & Whitney (PW) JT9D series turbofan engines was published in the Federal Register on November 24, 1999 (64 FR 66118). That action proposed to require installation of an improved No. 4 bearing internal oil pressure tube, initial and repetitive inspections of the No. 4 bearing oil pressure tube for TEC strut clearance and alignment, and, if necessary, replacement with serviceable parts, in accordance with PW Service Bulletin (SB) No. 5707, dated September 17, 1986, and in accordance with certain sections of the PW JT9D Engine Manuals: part numbers (P/Ns) 646028, 770407, 770408, 777210, 785059, and 754459. Start Printed Page 69661

Comments Received

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Reasons for This Modification and Inspection Program

One commenter states that the reports referenced in the NPRM focus only on engine fires, not uncontained engine failure and aircraft damage. Since the commenter has been using a tube of a design earlier to the one required by this AD for a long time without incident, the commenter requests that the FAA confirm the reasons for the modification and inspection program.

The FAA investigated the reports of oil fires in and around the No. 4 bearing area on the PW JT9D series turbofan engines and concluded that the heat generated by the oil fires could cause excessive thermal growth of the sixth stage LPT disk, liberation of the sixth stage LPT disk, uncontained engine failure, and damage to the airplane.

Applicability Section

One commenter requests the modification of the applicability section of the AD to specify the BG 700 series of the JT9D-7R4D engines. The applicability section of the NPRM includes the JT9D-7R4D series engines. The PW SB JT9D-7R4-72-289, dated March 26, 1986, applies to the BG 700 series. The commenter has the JT9D-7R4D (BG 900) series engines and would like the applicability section of the AD to reflect the BG 700 series.

The FAA agrees. The applicability section has been changed accordingly. Another commenter requests that the list of aircraft on which the affected engines may be installed be expanded to include Airbus A300 airplanes. The FAA agrees. The FAA will add Airbus A300 airplanes to the list, but cautions that this AD list is advisory in nature and does not limit the applicability of the AD to just those engines which are installed on the listed airplanes.

Engine Manual Part Numbers

One commenter requests that paragraph (b) reflect the JT9D-7A engine manual P/N 770408. The commenter also requests that the section title of 72-53-01 of the JT9D-59A engine manual, P/N 754459, be revised to reflect “Heavy Maintenance Check” instead of “Inspection 01.”

The FAA agrees. The engine manual P/Ns listed in the NPRM contain all engine models affected. However, the engine manufacturer has issued model-specific versions of these manuals. Therefore, it is possible that the operator may only have the model-specific version of the manual and not the all-encompassing engine manuals referred to in this AD. Revised paragraph (b) includes references to the model-specific JT9D engine manuals and to correct the reference to the title of Section 72-53-01 of P/N 754459.

Inspection Interval

Another commenter requests that the FAA weigh the benefits of conducting frequent inspections against the additional risks incurred by conducting the inspections. The commenter also states that it has not experienced an oil pressure tube failure due to TEC strut misalignment. The commenter considers an inspection interval at each heavy engine shop visit to be adequate, as opposed to every time the “N” or “P” flange is separated.

Two commenters recommend that the FAA replace the word “disconnected” with the word “separated.” The phrase “at the next time when the “N” or “P” flange is disconnected” occurs three times in the AD. One of the commenters suggests that since a flange is normally separated, not disconnected, this language may cause some confusion.

The FAA agrees in part. The FAA has decided to change the definition of shop visit to better reflect the original intent of the inspection. The original intent was that the inspections be performed during a complete disassembly of the TEC; this is the frequency interval contained in the engine manuals. The proposed language even if the recommended change from “disconnected” to “separated” is made, could still be perceived as a more frequent inspection interval than that intended by the FAA. Based on comments received and further coordination with the engine manufacturer, the FAA has developed a more precise definition. Therefore, the FAA has revised the phrase, “at the next time when the “N” or “P” flange is disconnected,” to read: “at the next turbine exhaust case disassembly when all hardware is stripped from the case.” These inspections are required at the same frequency contained in the engine manuals.

Request for Confirmation of Terminating Action

One commenter requests that the FAA confirm if there is a terminating action for the repetitive clearance and alignment check in accordance with the engine manual. The commenter questions if replacement of the pressure tube in accordance with PW SB 5707 and JT9D-7R4-72-289 constitutes the terminating action.

The FAA does not agree. There is no terminating action for this inspection. The inspections are required to make sure that there is sufficient tube clearance and that the TEC strut is aligned correctly. This inspection is an integral part of maintaining the airworthiness of this tube.

FAA's Determination

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Economic Analysis

There are approximately 2,310 engines of the affected design in the worldwide fleet. Approximately 1,183 of these engines are installed on airplanes of U.S. registry. Review of purchase orders indicate that approximately 1,547 pressure tubes have been sold to the airlines; therefore this action will affect no more than 763 engines. It will take approximately one work hour per engine to accomplish the proposed actions; the average labor rate is $60 per work hour. Required parts will cost approximately $1,465 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be no more than $1,163,575.

Regulatory Impact

This rule does not have federalism implications, as defined in Executive Order 13132, because it does 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this rule.

For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under 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. A final evaluation has been prepared for this action and is Start Printed Page 69662contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

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List of Subjects in 14 CFR Part 39

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Adoption of the Amendment

Accordingly, pursuant to 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:

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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. Section 39.13 is amended by adding the following new airworthiness directive:

2000-23-14 Pratt & Whitney: Amendment 39-11986. Docket No. 99-NE-25-AD.

Applicability: Pratt & Whitney (PW) JT9D-3A, -7, -7A, -7AH, -7H, -7F, -7J, -7Q, -7Q3, -20, -20J, -59A, -70A, and -7R4D (BG 700) series turbofan engines, installed on but not limited to Boeing 747 and 767, Airbus A300, and McDonnell Douglas DC-10 series airplanes.

Note 1:

This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance

Required as indicated, unless accomplished previously.

To prevent oil fires in and around the No. 4 bearing area, which could result in excessive growth of the sixth stage low pressure turbine (LPT) disk, liberation of the sixth stage LPT disk, uncontained engine failure, and damage to the airplane, accomplish the following:

Installation of Improved Hardware

(a) At the next disassembly of the turbine exhaust case (TEC) when all hardware is stripped from the case after the effective date of this AD, install an improved No. 4 bearing internal oil pressure tube in accordance with PW Service Bulletin (SB) No. 5707, dated September 17, 1986, and SB JT9D-7R4-72-289, dated March 26, 1986.

Inspections

(b) Perform initial and repetitive inspections of the No. 4 bearing oil pressure tube and TEC strut for clearance and alignment, and, if necessary, replace with serviceable parts, in accordance with the applicable PW JT9D Engine Manuals, part numbers (P/Ns) 646028, 770407, 770408, and 777210, Section 72-53-01, Turbine Exhaust Case Assembly—Inspection 01; P/N 785059, Section 72-53-05, Turbine Exhaust Case Assembly—Inspection/Check-01-Config-2; and P/N 754459, Turbine Exhaust Section—Heavy Maintenance, Section 72-53-01, Turbine Exhaust Case Assembly—Check, as follows:

(1) Initially inspect at the next disassembly of the TEC when all hardware is stripped from the case after the effective date of this AD.

(2) Thereafter, inspect at every disassembly of the TEC when all hardware is stripped from the case.

Alternative Methods of Compliance

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office (ECO). Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference

(e) The replacement of the oil pressure tube shall be done in accordance with PW Service Bulletin No. 5707, pages 1-7, dated September 17, 1986, and PW Service Bulletin No. JT9D-7R4-72-289, pages 1-6, dated March 26, 1986. The initial and repetitive inspections shall be done in accordance with the specified sections of the appropriate PW JT9D Engine Manual:

P/NSectionPagesDate
64602872-53-01805-809March 1, 1999.
75445972-53-01508October 15, 1999.
75445972-53-01508A-508DApril 15, 1999.
77040772-53-01805March 1, 1999.
77040872-53-01805March 1, 1999.
77721072-53-01805-806October 15, 1998.
77721072-53-01807April 15, 1999.
77721072-53-01815-818October 15, 1998.
78505972-53-05803March 15, 1999.
78505972-53-05807-810March 15, 1999.

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Pratt & Whitney, 400 Main Street, East Hartford, CT 06108; telephone: (860) 565-6600, fax: (860) 565-4503. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

(f) This amendment becomes effective on January 19, 2001.

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Issued in Burlington, Massachusetts, on November 7, 2000.

Donald E. Plouffe,

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

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[FR Doc. 00-29212 Filed 11-17-00; 8:45 am]

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