AD 99-08-15

This amendment adopts a new airworthiness directive (AD), that requires revisions to the Time Limits Section (TLS) of the manufacturer's Engine Manuals (EMs) for Pratt & Whitney (PW) PW4000 series turbofan engines to include required enhanced inspection of selected critical life-limited parts at each piece-part exposure. This amendment will also require an air carrier's approved continuous airworthiness maintenance program to incorporate these inspection procedures. This amendment is prompted by a Federal Aviation Administration (FAA) study of in-service events involving uncontained failures of critical rotating engine parts that indicated the need for improved inspections. The improved inspections are needed to identify those critical rotating parts with conditions that if allowed to continue in service, could result in uncontained failures. The actions specified by this AD are intended to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.

Final rule.

99-08-15 Pratt & Whitney: Amendment 39-11121. Docket 98-ANE-66-AD. Applicability: Pratt & Whitney PW4050, PW4052, PW4056, PW4060, PW4060A, PW4062, PW4060C, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4168, PW4168A, PW4460, PW4462, PW4164, PW4074, PW4074D, PW4077, PW4077D, PW4084, PW4084D, and PW4090 series turbofan engines installed on but not limited to Airbus A300, A310, and A330 series, Boeing 747, 767, 777 series, and McDonnell Douglas MD-11 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). 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 critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:
(a) Within the next 30 days after the effective date of this AD, revise the manufacturer's Time Limits section of the manufacturer's Engine Manual, Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822, 51A751, and 51A345, as applicable, for Pratt & Whitney PW4050, PW4052, PW4056, PW4060, PW4060A, PW4062, PW4060C, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, PW4164, PW4168, PW4074, PW4074D, PW4077, PW4077D, PW4084, PW4084D, and PW4090 series turbofan engines, and for air carrier operations revise the approved continuous airworthiness maintenance program, by adding the following: "MANDATORY INSPECTIONS
(1) Perform inspections of the following parts at each piece-part opportunity in accordance with the instructions provided in the PW4000 series Engine Cleaning, Inspection, and Repair (CIR) Manuals:

Part
Nomenclature
P/N
Manual
Section
Inspection
CIR
Manual
Hub, LPC
Assembly
50B221
(50B201 Detail)
72-31-07
02
51A357
Hub, LPC
Assembly
50B321
(50B301 Detail)
72-31-07
02
51A357
Hub, LPC
Assembly
51B321
(51B301 Detail)
72-31-07
02
51A357
Hub, LPC
Assembly
52B021
(52B001 Detail)
72-31-07
02
51A357
Hub, LPC
Assembly
51B631
(50B601 Detail)
72-31-07
02
51A750
Hub, LPC
Assembly
51B821
(51B801 Detail)
72-31-07
02
51A750
Hub, LPC
Assembly
52B521
(52B501 Detail)
72-31-07
02
51A750

(2) For the purposes of these mandatory inspections, piece-part opportunity means:
(i) The part is considered completely disassembled when accomplished in accordance with the disassembly instructions in the engine manufacturer's Engine Manual; and
(ii) The part has accumulated more than 100 cycles in service since the last piece-part opportunity inspection, provided that the part was not damaged or related to the cause for its removal from the engine."
(b) Except as provided in paragraph (c) of this AD, and notwithstanding contrary provisions in section 43.16 of the Federal Aviation Regulations (14 CFR 43.16), these mandatory inspections shall be performed only in accordance with the Time Limits section of the applicable PW4000 series Engine Manuals.
(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 Engine Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector (PMI), who may add comments and then send it to the Engine Certification Office.
Note2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(d) 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 airplane to a location where the requirements of this AD can be accomplished.
(e) FAA-certificated air carriers that have an approved continuous airworthiness maintenance program in accordance with the record keeping requirement of Sec. 121.369 (c) of the Federal Aviation Regulations [14 CFR 121.369 (c)] of this chapter must maintain records of the mandatory inspections that result from revising the Time Limits section of the Instructions for Continuous Airworthiness (ICA) and the air carrier's continuous airworthiness program. Alternately, certificated air carriers may establish an approved system of record retention that provides a method for preservation and retrieval of the maintenance records that include the inspections resulting from this AD, and include the policy and procedures for implementing this alternate method in the air carrier's maintenance manual required by Sec. 121.369 (c) of the Federal Aviation Regulations [14 CFR 121.369 (c)]; however, the alternate system must be accepted by the appropriate PMI and require the maintenance records be maintained either indefinitely or until the work is repeated. Records of the piece-part inspections are not required under Sec. 121.380 (a) (2) (vi) of the Federal Aviation Regulations [14 CFR 121.380 (a) (2) (vi)]. All other Operators must maintain the records of mandatory inspections required by the applicable regulations governing their operations.
Note 3: The requirements of this AD have been met when the engine manual changes are made and air carriers have modified their continuous airworthiness maintenance plans to reflect the requirements in the engine manuals.
(f) This amendment becomes effective on May 13, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) PW4000 series turbofan engines was published in the Federal Register on November 5, 1998 (63 FR 5943). That action proposed to require within the next 30 days after the effective date of this AD, revisions to the Time Limits Section (TLS) of the Engine Manuals, and, for air carriers, the approved continuous airworthiness maintenance program. Pratt & Whitney, the manufacturer of PW4000 series turbofan engines, has provided the FAA with a detailed proposal that identifies and prioritizes the critical life-limited rotating engine parts with the highest potential to hazard the airplane in the event of failure, along with instructions for enhanced, focused inspection methods. These enhanced inspections will be conducted at piece-part opportunity, as defined below in the compliance section, rather than specific inspection intervals.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. One commenter suggests three changes to the final rule:
a) The commenter states that paragraph (a)(2)(ii) is confusing as to inspection requirements for damaged parts. The FAA disagrees. Standardized language to define the piece-part condition, and thus trigger focused inspection, is required for uniform application of these new requirements for all operators. The language contained in this NPRM was developed by a broad group of FAA and industry members. Therefore, the piece-part definition will remain as written.
b) The commenter also recommends that to clearly specify the level to which the fan hub must be disassembled prior to FPI, each manual section referenced for the required inspections should also clearly state whether miscellaneous parts are to be removed. The FAA agrees. There are two areas on the PW4000 disks that are not typically disassembled, and after review, are not required to be disassembled to meet the intent of the proposed inspection. One of these areas is the tie-rod bolt holes, which may in some cases have repair bushings installed. The removal of these bushings would likely introduce more problems than they would solve, and a crack/failure in this region (at the disk OD) would not result in uncontainment. The other area is the spinner flange flared nuts. These are captive nuts and must be drilled/machined to be removed. Again, their removal/replacement would likely introduce more problems than would be solved, and crack/failure in this region would also not result in uncontainment. The final rule will be modified to clarify the required level of disassembly. This level of assembly is P/N 1A9021 - the piece-part level is 1A9001. Inspection at either level will satisfy the requirements of this AD.
c) The commenter also states thatthe FAA should urge the OEMs to agree upon universal pre-cleaning and fluorescent penetrant inspection procedures and to call them out in their service documents. The FAA partially agrees. The agency recognizes the need for, and is currently engaged in, several other initiatives that will provide standardized guidance on FPI precleaning, and several other procedural aspects of FPI inspection. The FAA will take future action once standardized procedures are developed and industry consensus is reached. Therefore, no changes will be made to this AD at this time.
Another commenter recommends four changes to this AD:
a) The commenter believes that critical compliance data is contained in the Discussion section of this AD, in the statement "For engines or engines modules that are approved for return to service...." The FAA does not agree. The AD mandates changes to the OEM's manual and Operators Continuous Airworthiness Program. The information referenced by the commenter is background information, not critical compliance data.
b) The commenter also believes that paragraph (e) of the proposed rule is unclear, and recommends that it be revised by eliminating the word "or" from the first sentence, and beginning a second sentence with "In lieu of the record...." The FAA concurs in part. Generally, record keeping requirements are addressed in other regulations and this AD does not change those requirements. The FAA has revised paragraph (e) of this AD with new language to clarify the record keeping aspects of the new mandatory inspections.
c) The commenter also suggests that disks be referred to by utilizing the term "All" instead of identifying them by specific P/N. The FAA partially agrees. Utilizing the reference ALL instead of specific P/N's is preferable in some aspects; it eliminates the possibility of underspecifying (omitting parts) that exists whenever using specific P/N's. However, because P & W has initiated the proposed manual changes and they areaccurate, they will not be changed at this time. In addition, future parts will be addressed via Intro into Service documentation, rather than with further AD's. These inspections will be built into the maintenance plan/documentation for new parts from the beginning. AD's were meant to deal only with parts already in service - new parts will incorporate these inspections from the beginning in the manufacturers' documentation.
d) The commenter also points out that "Inspection 06" referred to in the NPRM does not exist in the present manual. "Inspection 06" is not included in the present manual edition. P & W has submitted this change to their Tech Services group and it will appear in the next manual revision.
No comments were received on the economic analysis contained in the proposed rules. Based on that analysis, the FAA has determined that the annual per engine cost of $156 does not create a significant economic impact on small entities.
Additional editorial comments -Engine model PW2168A was omitted from the proposed rule and has been added to the Applicability section of this AD.
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.
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 it is 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, 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
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 adding the following new airworthiness directive: