AD 98-21-22 R1

This amendment revises an existing airworthiness directive (AD), applicable to Pratt & Whitney JT9D series turbofan engines, that currently requires initial and repetitive eddy current inspections (ECI) of 14th and 15th stage high pressure compressor (HPC) disks for cracks, and removal of cracked disks and replacement with serviceable parts. This amendment revises the definition of a shop visit to make compliance less restrictive, and adds references to a Nondestructive Inspection Procedure attached to applicable service bulletins. This amendment is prompted by feedback from operators saying that the shop visit definition in the current AD made AD compliance unnecessarily restrictive. The actions specified by this AD are intended to prevent 14th and 15th stage HPC disk rupture, which could result in an uncontained engine failure and damage to the airplane.

Final rule.

98-21-22 R1 PRATT & WHITNEY: Amendment 39-11424. Docket 95-ANE-69. Revises AD 98-21-22, Amendment 39-10830.
Applicability: Pratt & Whitney (PW) Model JT9D-59A, -70A, -7Q, -7Q3, and JT9D-7R4 series turbofan engines, with the following 14th and 15th stage high pressure compressor (HPC) disks installed: Part Numbers (P/Ns) 5000814-01, 790014, 789914, 790114, 5000815-01, 5000815-021, 704315, 704315-001, 786215, 786215-001, 704314, 789814, and 790214. These engines are installed on but not limited to Airbus A300 and A310 series aircraft, Boeing 747 and 767 series aircraft, 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 (f) 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 14th and 15th stage HPC disk rupture, which could result in an uncontained engine failure and damage to the airplane, accomplish the following: Inspections
(a) Inspect 14th stage HPC disks, P/N 5000814-01, in accordance with Nondestructive Inspection Procedure No. 858 (NDIP-858), dated November 7, 1995, attached to PW Alert Service Bulletin (ASB) No. JT9D-7R4-524, dated December 13, 1995, or Revision 1, dated June 26, 1997, as follows:
(1) Perform an initial eddy current inspection (ECI) for cracks as follows:(i) For disks with 7,000 or more cycles since new (CSN), and 3,000 or more cycles in service (CIS) since last shop visit, on the effective date of this AD, inspect within the next 1,000 CIS after the effective date of this AD, or at the next shop visit, whichever occurs first.
(ii) For disks with 7,000 or more CSN, and less than 3,000 CIS since last shop visit, on the effective date of this AD, inspect within 4,000 CIS since the last shop visit, or at the next shop visit, whichever occurs first.
(iii) For disks with less than 7,000 CSN on the effective date of this AD, inspect at the next shop visit after the effective date of this AD, but before exceeding 4,000 CIS since last shop visit, or 8,000 CSN, whichever occurs later.
(iv) For uninstalled disks on or after the effective date of this AD, inspect prior to installation.
(2) Thereafter, perform ECI for cracks at intervals not to exceed 4,000 CIS since last ECI.
(3) Prior to further flight, remove cracked disks and replace with serviceable parts.
(b) Inspect 14th stage HPC disks, P/Ns 790014, 789914, 790114, and 15th stage HPC disks, P/N's 5000815-01, 5000815-021, 704315, 704315-001, 786215, and 786215-001, in accordance with NDIP-858, dated November 7, 1995, attached to PW ASB No. JT9D-7R4-A72-524, dated December 13, 1995, or Revision 1, dated June 26, 1997, or PW ASB No. A6232, dated December 13, 1995, or Revision 1, dated January 11, 1996, or Revision 2, dated June 26, 1997, as applicable, as follows:
(1) Perform an initial ECI for cracks as follows:
(i) For disks with 6,500 or more CSN, and 3,000 or more CIS since last shop visit, on the effective date of this AD, inspect within the next 1,000 CIS after the effective date of this AD, or at the next shop visit, whichever occurs first.
(ii) For disks with 6,500 or more CSN, and less than 3,000 CIS since last shop visit, on the effective date of this AD, inspect within 4,000 CIS since the last shop visit, or at the next shop visit, whichever occurs first.
(iii) For disks with less than 6,500 CSN on the effective date of this AD, inspect at the next shop visit after the effective date of this AD, but before exceeding 4,000 CIS since last shop visit, or 7,500 CSN, whichever occurs later.
(iv) For uninstalled disks on or after the effective date of this AD, inspect prior to installation.
(2) Thereafter, perform ECI for cracks at intervals not to exceed 4,000 CIS since last ECI.
(3) Prior to further flight, remove cracked disks and replace with serviceable parts.
(c) Inspect 14th stage HPC disks, P/Ns 704314, 789814, and 790214, in accordance with NDIP-858, dated November 7, 1995, attached to PW ASB No. A6232, original issue, dated December 13, 1995, or Revision 1, dated January 11, 1996, or Revision 2, dated June 26, 1997, as follows:
(1) Perform an initial ECI for cracks as follows:
(i) For disks with 2,000 or more CSN, and 2,000 or more CIS since last shop visit, on the effective date of this AD, inspect within the next 1,000 CIS after the effective date of this AD, or at the next shop visit, whichever occurs first.
(ii) For disks with 2,000 or more CSN, and less than 2,000 CIS since last shop visit, on the effective date of this AD, inspect within 3,000 CIS since the last shop visit, or at the next shop visit, whichever occurs first.
(iii) For disks with 2,000 or more CSN, and no previous shop visits, inspect within 3,000 CIS after the effective date of this AD, or at the next shop visit, whichever occurs first.
(iv) For disks with less than 2,000 CSN on the effective date of this AD, inspect at the next shop visit after the effective date of this AD, but before exceeding 5,000 CSN.
(iv) For uninstalled disks on or after the effective date of this AD, inspect prior to installation.
(2) Thereafter, perform ECI for cracks at intervals not to exceed 3,000 CIS since last ECI.
(3) Prior to further flight, remove cracked disks and replace with serviceable parts. Inspection Report
(d) Within 30 days of inspection, report inspection results on the form labeled "14th and 15th Stage HPC Disk Inspection Report," to Pratt & Whitney Customer Technical Support. The fax number is listed on that form which is attached to PW ASB No. JT9D-7R4-A72-524, Revision 1, dated June 26, 1997, or PW ASB No. A6232, Revision 2, June 26, 1997. Reporting requirements have been approved by the Office of Management and Budget and assigned OMB control number 2120-0056.
Definition
(e) For the purpose of this AD, a shop visit is defined as a low pressure turbine module removal.
Alternative Method of Compliance
(f) 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. Ferry Flight
(g) 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.
Incorporation by Reference
(h) The actions required by this AD shall be done in accordance with the following PW service documents:

Document No
Pages
Revision
Date
ASB No. A6232
1
2
June 26, 1997

2
Original
December 13, 1995

3,4
1
January 11, 1996

5,6
2
June 26, 1997

7-10
Original
December 13, 1995
Total Pages: 10.

ASB No. JT9D-7R4-A72-524
1
1
June 26, 1997

2-5
Original
December 13, 1995

6,7
1
June 26, 1997

8-11
Original
December 13, 1995
Total Pages: 11

NDIP-858
1-33
Original
November 7, 1995
Total Pages: 33

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, Publications Department, Supervisor Technical Publications Distribution, M/S 132-30, 400 Main St., East Hartford, CT 06108; telephone (860) 565-5570. 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
(i) This amendment becomes effective on January 18, 2000.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by revising airworthiness directive (AD) 98-21-22, Amendment 39-10830 (63 FR 55500, October 16, 1998), which is applicable to Pratt & Whitney (PW) JT9D-59A, -70A, -7Q, -7Q3, and JT9D-7R4 series turbofan engines, was published in the Federal Register on March 30, 1999 (64 FR 15137). The proposal would change the definition of a shop visit from what appears in the current AD, "the induction of an engine into the shop for scheduled maintenance" to "a low pressure turbine module removal." In addition, the proposal would add references to the Nondestructive Inspection Procedure No. 858 (NDIP-858), dated November 7, 1995, attached to the various versions of the referenced alert service bulletins (ASBs), which was inadvertently omitted from the current AD. Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. Difference between Service Documents and AD
One commenter notes that the reinspection interval for the 14th stage disk in the proposal differs from the reinspection interval provided in the applicable service documents. While the proposal provides for reinspection at intervals not to exceed 4,000 cycles-in-service (CIS) since last eddy current inspection (ECI), the ASB calls for reinspection whenever the high pressure compressor is disassembled sufficiently to access the disk, defined as the removal of the low pressure turbine shaft, after accumulating 100 or more cycles since last inspection. The commenter states that this difference creates a conflict between the proposed AD and the service documents.
The Federal Aviation Administration (FAA) does not concur. The proposal would incorporate ASB JT9D-7R4-A72-524 by reference only for the purpose of providing direction on how to perform the inspection and the reject criteria. The proposal contains its own reinspection interval, which would take precedence over any the interval contained in the service documents for purposes of complying with the proposed AD. There is no conflict. The FAA views the reinspection interval in the service documents as more conservative than that required by the proposed AD. The proposed AD, however, does not prohibit additional inspections performed in accordance with the interval stated in the service documents. The FAA has determined that the reinspection interval provided in the proposal provides a sufficient level of safety. Commenter Concurs
One commenter agrees with the proposal as stated.
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. No Additional Economic Impact
Since this revised rule only changes the definition of the shop visit and adds reference tothe NDIP, there is no effect on the economic analysis. Regulatory Impact
The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
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 itis contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39
Air Transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
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: PART 39 - AIRWORTHINESS DIRECTIVES
Authority: 49 U.S.C. 106(g), 40113, 44701. 39.13 [Amended]
2. Section 39.13 is amended by removing Amendment 39-10830 (63 FR 55500, October 16, 1998), and by adding a new airworthiness directive, Amendment 39-11424, to read as follows: