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Proposed Rule

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney JT9D series turbofan engines. This proposal would require initial and repetitive detailed eddy current inspections for cracks in 1st stage high pressure turbine (HPT) disks, and, if necessary, replacement with serviceable parts. This proposal is prompted by the finding of a crack in the web of one cooling air hole on a 1st stage HPT disk. The actions specified by the proposed AD are intended to prevent 1st stage HPT disk cracking, which could result in an uncontained engine failure and damage to the aircraft.

DATES:

Comments must be received by May 8, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-ANE-56-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 0610; telephone 860-565-8770, fax 860-565-4503. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

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FOR FURTHER INFORMATION CONTACT:

Wego Wang, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone 781-238-7134, fax 781-238-7199.

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SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-ANE-56-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-ANE-56-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The Federal Aviation Administration (FAA) has received a report of a cracked 1st stage high pressure turbine (HPT) disk installed on a Pratt & Whitney (PW) Model JT9D-7R4E turbofan engine. The crack was found during a routine maintenance inspection. The investigation revealed a 4-inch radial crack on the HPT 1st stage disk progressing through the web of one cooling air hole. The subject disk was returned to PW for investigation. Eddy current inspection (ECI) and fluorescent penetrant inspection (FPI) of the disk revealed axial indications on the surface of one 0.313-0.323 inch diameter cooling air hole surface that progressed completely through the web. Further examination revealed a severely worked layer extending to a maximum depth of 0.006 inch from the surface of the hole. No other cooling air hole exhibited cracks. This condition, if not corrected, could result in 1st stage HPT disk cracking, which could result in an uncontained engine failure and damage to the aircraft.

Service Information

The FAA has reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) JT9D-7R4-A72-563, and ASB JT9D A6367, both dated July 28, 1999, that describe procedures for detailed ECI of 1st stage HPT disks for cracks. Start Printed Page 11941

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require initial and repetitive detailed ECI for cracks in 1st stage HPT disks, and, if necessary, replacement with serviceable parts. The actions would be required to be accomplished in accordance with the ASB described previously.

Economic Analysis

There are approximately 330 engines of the affected design in the worldwide fleet. The FAA estimates that 220 engines installed on aircraft of US registry would be affected by this proposed AD, that it would take approximately 4.5 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $165,000 per engine. Based on these figures, the total cost impact of the proposed AD on US operators is estimated to be $36,359,400.

Regulatory Impact

This proposal does not have federalism implications, as defined in Executive Order No. 13132, because it 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposal.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order No. 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting 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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The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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:

Pratt & Whitney: Docket No. 99-ANE-56-AD.

Applicability: Pratt & Whitney (PW) JT9D-7R4D, -7R4D1, -7R4E, -7R4E1 (AI-500), -7, -7A, -7AH, -7H, -7F, and -20 series turbofan engines, installed on but not limited to Boeing 747 and 767 series, McDonnell Douglas DC-10 series, and Airbus Industrie A300 series aircraft.

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 (d) 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 1st stage high pressure turbine (HPT) disk cracking, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

JT9D Series

(a) For PW JT9D-7, -7A, -7AH, -7H, -7F, and -20 series turbofan engines, with 1st stage HPT disks, part numbers (P/Ns) 761401, 811401, 823401, 825601, 826001, and 826301:

Initial Inspection

(1) Perform the initial detailed eddy current inspection (ECI) for cracks in accordance with the Accomplishment Instructions of PW Alert Service Bulletin (ASB) No. JT9D A6367, dated July 28, 1999.

(2) Inspect at the following compliance times, depending on whether parts have had prior fluorescent penetrant inspections (FPI) or not.

Initial Compliance Times

No Prior FPI

(3) The following are the initial compliance times for parts that have had no prior FPI:

(i) For disks with more than 8,000 total part cycles-since-new (CSN) on the effective date of this AD, inspect within 250 cycles-in-service (CIS) after the effective date of this AD.

(ii) For disks with at least 6,000 CSN though no more than 8,000 total part CSN on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 4,000 CSN though no more than 5,999 total part CSN on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 4,000 total part CSN on the effective date of this AD, inspect prior to accumulating 6,000 total part CSN.

Prior FPI Accomplished

(4) The following are the initial compliance times for parts that have had a previous FPI:

(i) For disks with more than 8,000 CIS since last FPI on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 6,000 CSN though no more than 8,000 CIS since last FPI on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 4,000 CSN though no more than 5,999 CIS since last FPI on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 4,000 CIS since last FPI on the effective date of this AD, inspect prior to accumulating 6,000 CIS since last FPI on the effective date of this AD.

Repetitive Inspections

(5) Thereafter, perform detailed ECI for cracks:

(i) At intervals not to exceed 6,000 CIS since last ECI.

(ii) Inspect in accordance with the Accomplishment Instructions of PW ASB No. JT9D A6367, dated July 28, 1999.

Cracked Disks

(6) Prior to further flight, replace cracked disks with serviceable parts.

JT9D-7R4 Series

(b) For PW JT9D-7R4D, -7R4D1, -7R4E, and -7R4E1 (AI-500) series turbofan engines, with 1st stage HPT disks, P/N 825601:

Initial Inspection

(1) Perform the initial detailed ECI for cracks in accordance with the Accomplishment Instructions of PW ASB No. JT9D-7R4-A72-563, dated July 28, 1999.

(2) Inspect at the following compliance times, depending on whether parts have had prior FPI or not.

Initial Compliance Times

No Prior FPI

(3) The following are the initial compliance times for parts that have had no prior FPI:

(i) For disks with more than 10,000 total part CSN on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 8,000 CSN though no more than 10,000 total part CSN on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD. Start Printed Page 11942

(iii) For disks with at least 6,000 CSN though no more than 7,999 total part CSN on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 6,000 total part CSN on the effective date of this AD, inspect prior to accumulating 8,000 total part CSN.

Prior FPI Accomplished

(4) The following are the initial compliance times for parts that have had a previous FPI:

(i) For disks with more than 10,000 CIS since last FPI on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 8,000 CSN though no more than 10,000 CIS since last FPI on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 6,000 CSN though no more than 7,999 CIS since last FPI on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 6,000 CIS since last FPI on the effective date of this AD, inspect prior to accumulating 8,000 CIS since last FPI on the effective date of this AD.

Repetitive Inspections

(5) Thereafter, perform detailed ECI for cracks:

(i) At intervals not to exceed 8,000 CIS since last ECI.

(ii) Inspect in accordance with the Accomplishment Instructions of PW ASB No. JT9D-7R4-A72-563, dated July 28, 1999.

Cracked Disks

(6) Prior to further flight, replace cracked disks with serviceable parts.

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.

Ferry Flights

(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 aircraft to a location where the inspection requirements of this AD can be accomplished.

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Issued in Burlington, Massachusetts, on February 23, 2000.

David A. Downey,

Assistant Manager, Engine and Propeller Directorate Aircraft Certification Service.

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[FR Doc. 00-5011 Filed 3-6-00; 8:45 am]

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