Airworthiness directives: Pratt & Whitney,

[Federal Register: January 11, 1999 (Volume 64, Number 6)]

[Proposed Rules]

[Page 1552-1554]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr11ja99-19]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-ANE-54]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

[[Page 1553]]

SUMMARY: This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT9D series turbofan engines, that currently requires initial and repetitive in-shop or on-wing inspections of the diffuser case rear rail for cracking, and removal, if necessary, of the diffuser case. This action would reduce the allowable crack length, reduce the inspection intervals, and introduce an improved inspection method. This proposal is prompted by a report of an additional diffuser case rupture, and improved understanding of crack propagation rates. The actions specified by the proposed AD are intended to prevent diffuser case rupture, an uncontained engine failure, and damage to the aircraft.

DATES: Comments must be received by March 12, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 94-ANE-54, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ad- engineprop@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 06108; telephone (860) 565-6600, 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.

FOR FURTHER INFORMATION CONTACT: Peter White, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7128, fax (781) 238-7199.

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 in triplicate 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 filedin 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 94-ANE-54.'' 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. 94-ANE-54, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On December 29, 1994, the Federal Aviation Administration (FAA) issued airworthiness directive AD 94-26-06, Amendment 39-9102 (59 FR 67176, December 29, 1994), applicable to Pratt & Whitney (PW) JT9D-59A, -70A, -7Q, and -7Q3 series turbofan engines, to require initial and repetitive in-shop or on-wing inspections of the diffuser case rear rail for cracking, and removal, if necessary, of the diffuser case. That action was prompted by multiple reports of diffuser case rear rail cracking and two reports of diffuser case rupture. That condition, if not corrected, could result in diffuser case rupture, uncontained engine failure, and damage to the aircraft.

Since the issuance of that AD, the FAA has received a report of an additional diffuser case rupture. Based on new information regarding crack propagation rates on repaired diffuser cases, on-wing and in-shop findings of additional cracked diffuser cases and further refinement of inspection techniques the manufacturer has significantly changed the inspection program.

The FAA has reviewed and approved the technical contents of PW JT9D Service Bulletin (SB) No. 5749, Revision 8, dated October 30, 1998, that describes procedures for initial and repetitive in-shop and on- wing fluorescent penetrant inspections (FPI) and eddy current inspections (ECI) of diffuser case rear rails for cracks. PW JT9D SB No. 5749, Revision 8, dated October 30, 1998, references PW JT9D SB No. 5654, dated January 21, 1986, that describes procedures for blending and polishing the rear rail top surface to remove electrochemical machining (ECM) marks and fatigued material; and PW JT9D SB No. 5768, Revision 6, dated March 23, 1995, that describes procedures for skim cutting the diffuser case rear rail top surface to remove electrochemical machining (ECM) marks and fatigued material; and PW JT9D SB No. 6197, Revision 1, dated March 23, 1995, that describes procedures for skim cutting fatigued material from the rear rail top surface. PW JT9D SB No. 5749, Revision 8, dated October 30, 1998, varies the initial and repetitive inspection intervals based on the incorporation of these SBs referenced above, and the parts' age in cycles.

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 supersede AD 94-26-06 to reduce the allowable crack length, reduce the inspection intervals, and introduce an improved inspection method. Initial and repetitive intervals would vary depending upon rail improvement SB incorporation--higher inspection intervals are allowed after surface finish improvements of the rear rail top surface to remove ECM marks, fatigued material, and sharp edges have been incorporated. The actions would be required to be accomplished in accordance with the appropriate SBs described previously.

There are approximately 566 engines of the affected design in the worldwide fleet. The FAA estimates that 157 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 29 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $273,180.

The regulations proposed herein would not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient

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federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this 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) 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

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:

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.

   Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-9102 (59 FR 67176, December 29, 1994), and by adding a new airworthiness directive to read as follows:

   Pratt & Whitney: Docket No. 94-ANE-54. Supersedes AD 94 2606, Amendment 39-9102.

   Applicability: Pratt & Whitney (PW) JT9D-59A, -70A, 7Q, and -7Q3 series turbofan engines, installed on but not limited to Airbus A300 series, Boeing 747 series, and McDonnell Douglas DC-10 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 (b) 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 diffuser case rupture, an uncontained engine failure, and damage to the aircraft, accomplish the following:

   (a) Perform initial and repetitive fluorescent penetrant inspections (FPI) or eddy current inspections (ECI) of diffuser case rear rails for cracks in accordance with the Accomplishment Instructions of PW JT9D (SB) No. 5749, Revision 8, dated October 30, 1998, as follows:

   (1) For engines on-wing that have not had the diffuser case rear rail FPI or ECI inspected using the procedures referenced in PW JT9D SB No. 5749, Revision 4, dated April 25, 1989; Revision 5, dated September 29, 1995; Revision 6, dated May 8, 1998; Revision 7, dated August 19, 1998; or Revision 8, dated October 30, 1998; Section 2, Part 1A (1)-(3), accomplish the following:

   (i) Perform an initial on-wing inspection within 25 cycles of the effective date of this AD in accordance with Section 2, Part 2 of PW JT9D SB No. 5749, Revision 8, dated October 30, 1998.

   (ii) Thereafter, except as provided in paragraph (a)(4) of this AD, perform on-wing inspections in accordance with the time requirements listed in Section 2, Part 2 of PW JT9D SB No. 5749, Revision 8, dated October 30, 1998.

   (2) For engines on-wing that have had the diffuser case rear rail FPI or ECI inspected using the procedures referenced in PW JT9D SB No. 5749, Revision 4, dated April 25, 1989; Revision 5, dated September 29, 1995; Revision 6, dated May 8, 1998; Revision 7, dated August 19, 1998; or Revision 8, dated October 30, 1998; Section 2, Part 1 A (1)-(3), perform initial and repetitive on-wing inspections in accordance with PW JT9D SB 5749, Revision 8, dated October 30, 1998, within the time requirements listed in Section 2, Part 2 of that SB, except as provided in paragraph (a)(4) of this AD.

   (3) Remove from service diffuser cases that do not meet the return to service criteria stated in PW JT9D SB No. 5749, Revision 8, dated October 30, 1998, Section 2, Part 2 D, and replace with serviceable parts.

   (4) For engines that are overdue for an inspection on the effective date of this AD, accomplish the required inspection within 25 cycles in service of the effective date of this AD.

   (b) 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. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.

   Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.

   (c) Special flight permits may be issued in accordance with sections 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 requirements of this AD can be accomplished.

   Issued in Burlington, Massachusetts, on January 5, 1999. David A. Downey, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.

   [FR Doc. 99-492Filed1-8-99; 8:45 am]

   BILLING CODE 4910-13-P