[Federal Register Volume 64, Number 70 (Tuesday, April 13, 1999)]
[Rules and Regulations]
[Pages 17947-17949]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-8865]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-66-AD; Amendment 39-11121; AD 99-08-15]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: 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.

DATES: Effective May 13, 1999.

ADDRESSES: The information contained in this AD 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: 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--3 the piece-part level is 1A9001. Inspection at 
either level will satisfy the requirements of this AD.
    (c) The commenter also states that the 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

[[Page 17948]]

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 are accurate, 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:

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 . 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:

[[Page 17949]]



----------------------------------------------------------------------------------------------------------------
                                                                                Manual
              Part Nomenclature                             P/N                 Section   Inspection  CIR Manual
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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
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    (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.

    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.

    (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.

    Issued in Burlington, Massachusetts, on April 2, 1999.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 99-8865 Filed 4-12-99; 8:45 am]
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