[Federal Register Volume 65, Number 116 (Thursday, June 15, 2000)]
[Rules and Regulations]
[Pages 37473-37476]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-14789]



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  Federal Register / Vol. 65, No. 116 / Thursday, June 15, 2000 / Rules 
and Regulations  

[[Page 37473]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-66-AD; Amendment 39-11780; AD 2000-12-02]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Pratt & Whitney PW4000 Series Turbofan 
Engines, that currently requires revisions to the Time Limits Section 
of the manufacturer's Engine Manuals (EM's) to include required 
enhanced inspection of selected critical life-limited parts at each 
piece-part exposure. This action adds additional critical life-limited 
parts for enhanced inspection. This amendment is prompted by additional 
focused inspection procedures for other critical life-limited rotating 
engine parts that have been developed by the manufacturer. 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 September 13, 2000.

ADDRESSES: The rulemaking docket may be examined at the Federal 
Aviation Administration (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) by superseding (AD) 99-08-15, 
Amendment 39-11121 (64 FR 17947), that is applicable to certain Pratt & 
Whitney series turbofan engine was published in the Federal Register on 
October 7, 1999 (64 FR 54582). The original AD required enhanced 
inspection of selected critical life-limited rotating components in the 
fan rotor at each piece-part exposure. This amendment will require 
additional enhanced inspections of selected critical life-limited 
rotating components in the HPT rotor at each piece-part exposure.

New Procedures and Parts

    Since the issuance of that AD, additional focused inspection 
procedures for other critical life-limited rotating engine parts have 
been developed. The new parts are the:
     High Pressure Turbine (HPT) 1st stage airseal--on certain 
models
     HPT 2nd stage airseal--on certain models
     HPT 1st stage (front) hub
     HPT 2nd stage (rear) hub
    This AD will require an air carrier's approved continuous 
airworthiness maintenance program to incorporate these inspection 
procedures, and will revise the Time Limits Section of the 
manufacturer's Engine Manual.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the eleven comments received.

Length of Comment and Inspection Periods

    Two comments express concerns regarding the length of the comment 
period, and the length of the initial compliance time allowed to 
incorporate the manufacturer's instructions into an applicant's 
maintenance plan. One comment asks that the final rule not be issued 
and the comment period extended until after the manufacturer publishes 
the new inspection procedures in the manufacturer's manuals. Another 
comment asks that the initial compliance time be extended from 30 to 90 
days to better accommodate the manufacturer's planned manual change 
schedule.
    The FAA does not agree. The FAA believes that the nature and scope 
of the added inspections will not be significantly different from 
existing inspections. In addition, the effective date of this AD has 
been extended to 90 days after publication to allow time for the 
specific procedures to be published. Operators may submit comments on 
the specific procedures once they are published and the FAA will 
consider extending the effective date further or additional rulemaking, 
as necessary. The extra time until the AD becomes effective should also 
allow the manufacturer to issue a manual revision. The FAA does not 
believe, however, that this final rule need be delayed pending the 
publication of the inspection procedures, or the initial compliance 
time extended to accommodate the manufacturer's manual revision cycle.

More Than One Engine Model Covered by AD

    One comment notes that engine models covered by two different Type 
Certificates are affected by this AD, and feels that a separate AD 
should be issued to cover the engine models covered by each Type 
Certificate. Another comment notes that, to avoid confusion, the tables 
in proposed paragraph (a) should be divided by engine model. The 
comment points out that as presently constructed the AD requires 
information related to different engine models to be incorporated into 
all manuals. That could cause confusion as information unrelated to a 
particular engine model would appear in that model's manuals.
    The FAA does not agree that products covered by different type 
certificates must be addressed with separate AD's. The FAA often 
includes products covered by different type designs in a single AD. 
When the same unsafe condition exists or is likely to develop on 
products covered by different type designs, a single AD covering all 
the affected products works more efficiently than duplicating the same 
corrective action into multiple AD's. The single AD should place no 
undue burden on operators, and may actually simplify administrative 
responsibilities by reducing the number of AD's required to be tracked. 
This AD applies to engines covered by three Type Certificates.

[[Page 37474]]

    The FAA does agree, however, that the tables in paragraph (a) 
should be separated by engine model. Paragraph (a) will be changed to 
include a provision that only the table that applies to a particular 
engine model should be incorporated into that engine model's manual. 
This will eliminate the potential confusion in having information not 
applicable to that engine in its manual.

HPC Parts Included in the Proposed Rule

    Two comments question the need for this AD noting that the lower 
risk associated with HPC disk failures make the inclusion of HPC parts 
in the enhanced inspection program unnecessary.
    The FAA partially agrees. The failure of an HPC disk with a full 
webbed bore configuration such as the PW4000 poses a hazard to the 
aircraft due to the energy associated with these large, heavy, rapidly 
spinning components. While the risk factors for HPC failures are 
somewhat lower than those associated with HPT and fan failures, the FAA 
feels this could be due to several factors, which will need to be 
evaluated. Until further studies have been completed, the FAA will 
eliminate the HPC parts from the enhanced inspection program for these 
engine models. The FAA will continue to review and evaluate the data 
and will take appropriate action when this review is completed.

Part Numbers Used To Identify Parts To Be Inspected

    One comment notes that the use of specific part numbers (P/N's) to 
identify the parts needing enhanced inspection raises concerns. The 
comment notes that the use of part numbers places additional undue 
burden on operators who must keep track of the manual changes to ensure 
consistency with P/N's, and creates a need for downstream revisions to 
the AD as additional part number disks are introduced into service.
    The FAA concurs. During the process of preparing this rule, the FAA 
considered utilizing the term ``ALL'' rather than specific part 
numbers, but not all part numbers associated with a specific part need 
enhanced inspection. For example, HPT airseals from various engine 
models may or may not need enhanced inspection, depending on the 
configuration of the part. Only those parts that are likely to hazard 
the aircraft by their failure are included in the enhanced inspection 
program. Therefore, the ``ALL'' terminology could not be used 
consistently across engine models. However, in response to another 
comment the FAA is changing the structure of this AD to separate the 
tables by engine model. With that change each table may use the term 
``ALL'' and eliminate the need for specific P/N's.

Discussion Section Changed From Original NPRM

    One comment notes that the preamble published with this Notice of 
Proposed Rulemaking (NRPM) did not include the same guidelines 
concerning required enhanced inspections as the preamble for the NPRM 
published for the current AD. The comment asks that the FAA add those 
guidelines to the final rule.
    The FAA does not agree. The inspection program established by the 
current AD has not been changed. The NPRM proposed to add additional 
parts to the list of parts that must be inspected, but does not change 
how air carriers must manage the inspection program. Future AD's may be 
issued to introduce additional intervention strategies in order to 
further reduce uncontained engine failures. These may include AD's to 
add new parts to the list of parts to be inspected. The inspection 
program established by the current AD will remain unchanged unless 
specifically changed in a future proposal.

Manual References Should Include Revision Level and Issue Date

    Two comments note that the proposed rule does not reference a 
specific revision level or issue date of the Clean, Inspect and Repair 
(CIR) manual. The comments express concern that without a specific 
manual revision referenced operators will not know if the FAA expects 
compliance with future revisions to the manual, which may be issued 
without notice and public comment. For that reason, the comments 
suggest that the manual references in paragraph (a) include a revision 
level and issue date.
    The FAA disagrees. Unlike the typical incorporation by reference, 
this AD does not require inspections to be accomplished ``in accordance 
with'' a specific service document or manual. This AD requires changes 
to the Airworthiness Limitations Section (ALS) of the Instructions for 
Continued Airworthiness (ICA), and to air carrier operator's 
maintenance plans, in order to include mandatory inspections. Once 
included in the ALS, the enhanced inspections become operational limits 
that must be followed. The manufacturer will update the sections of 
their manuals to incorporate the inspections, and those changes, as 
well as any future changes, will be coordinated with the FAA. It is not 
the intent of this AD, however, to mandate the use of any specific 
manual revision, but only to require the accomplishment of an enhanced 
inspection. If the FAA should find it necessary to mandate compliance 
with a specific future revision of the manual, then the FAA will 
undertake a new rulemaking action and provide notice and an opportunity 
for comment.

Other Corrections

    One comment notes that the table in proposed paragraph (a) lists 
CIR manual 51A357 as the manual to use when inspecting HPT first stage 
hub, P/N 50L761, while that part is only found in CIR manual 51A750. 
The FAA agrees, and will make that correction in the final rule.
    One comment points out that detail HPT 1st stage disk P/N 51L901 is 
referenced in the manufacturer's parts catalog, but is not referenced 
in the corresponding CIR. The FAA agrees. However, the corresponding 
assembly P/N is called out in the CIR. The ``ALL'' reference now 
utilized in the AD eliminates any issues arising from the Detail versus 
Assembly P/N reference issue. In addition, the FAA has added the 
definition of ``piece-part opportunity'' to (a)(2) to clarify that the 
disks must be inspected when torn down to either the piece part or part 
assembly P/N level where the inspection can still be accomplished.
    One comment notes that paragraph (e) of the proposed rule contains 
the phrase ``of this chapter'' following a reference to Sec. 121.369 
(c) of the Federal Aviation Regulations [14 CFR 121.369 (c)]. The 
comment asks that this phrase be deleted in the interest of clarity. 
The FAA agrees, and will make that correction the final rule.

Engines Affected by the Ruling

    One commenter notes the PW4098, PW4090D and PW4090-3 models are not 
affected by the AD, and questions why they are excluded from the rule. 
The FAA partially agrees. The PW4098 and PW4090D fan hardware were 
included in the NPRM, and an explanation for this inclusion is provided 
in the NPRM. Coincident with the inclusion of this hardware, these two 
models were included in the Applicability statement. The PW4090-3 
engine model was certified at a later date, and was not included in the 
NPRM. The final rule will be modified to include the PW4090-3 engine 
model in the Applicability section for completeness, as were the PW4098 
and PW4090D.

[[Page 37475]]

Economic Analysis

    No comments were received on the economic analysis contained in the 
proposed rules. The FAA has determined that the annual cost of 
complying with this AD does not create a significant economic impact on 
small entities.
    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.

Regulatory Impact

    This final rule does not have federalism implications, as defined 
in Executive Order 13132, because it does 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 final rule.
    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 removing Amendment 39-11121 (64 FR 
17947, April 13, 1999), and by adding a new airworthiness directive, to 
read as follows:

2000-12-02  Pratt & Whitney: Amendment 39-11780. Docket No. 98-ANE-
66-AD. Supersedes AD 99-08-15, Amendment 39-11121.

    Applicability: Pratt & Whitney (PW) Model PW4050, PW4052, 
PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A, 
PW4158, PW4160, PW4460, PW4462, PW4168, PW4168A, PW4164, PW4074, 
PW4074D, PW4077, PW4077D, PW4084, PW4084D, PW4090, PW4090D, PW4090-3 
and PW4098 turbofan engines, installed on but not limited to Airbus 
A300, A310, and A330 series, Boeing 747, 767, and 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) 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 critical life-limited rotating engine part failure, 
which could result in an uncontained engine failure and damage to 
the airplane, accomplish the following:

Inspections

    (a) Within the next 30 days after the effective date of this AD, 
revise the Time Limits Section of the manufacturer's Engine Manual 
(EM), Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822, 51A751, or 
51A345, as applicable, for PW Model PW4050, PW4052, PW4056, PW4060, 
PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A, PW4158, PW4160, 
PW4460, PW4462, PW4168, PW4168A, PW4164, PW4074, PW4074D, PW4077, 
PW4077D, PW4084, PW4084D, PW4090, PW4090D, PW4090-3 and PW4098 
turbofan engines, and for air carrier operations revise the approved 
mandatory inspections section of the continuous airworthiness 
maintenance program, to read as follows:

    ``MANDATORY INSPECTIONS
    (1) Perform inspections of the following parts at each piece-
part opportunity in accordance with the instructions provided in the 
applicable PW4000 series Engine Cleaning, Inspection, and Repair 
(CIR) Manuals:
    For Engine Manual 50A605 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, Front Compressor...............  ALL....................     72-31-07  Insp/Check-02..........       51A357
Hub, Turbine Front (Stage 1)........  ALL....................     72-52-05  Insp/Check-02..........       51A357
Hub, Turbine Intermediate Rear        ALL....................     72-52-06  Insp/Check-02..........       51A357
 (Stage 2).
----------------------------------------------------------------------------------------------------------------

    For Engine Manual 50A443 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, Front Compressor...............  ALL....................     72-31-07  Insp/Check-02..........       51A357
Hub, Turbine Front (Stage 1)........  ALL....................     72-52-05  Insp/Check-02..........       51A357
Hub, Turbine Intermediate Rear        ALL....................     72-52-06  Insp/Check-02..........       51A357
 (Stage 2).
----------------------------------------------------------------------------------------------------------------

    For Engine Manual 50A822 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, Front Compressor...............  ALL....................     72-31-07  Insp/Check-02..........       51A357
Hub, Turbine Front (Stage 1)........  ALL....................     72-52-05  Insp/Check-02..........       51A357

[[Page 37476]]

 
Hub, Turbine Intermediate Rear        ALL....................     72-52-06  Insp/Check-02..........       51A357
 (Stage 2).
----------------------------------------------------------------------------------------------------------------

    For Engine Manual 51A342 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, LPC Assembly...................  ALL....................     72-31-07  Insp/Check-02..........       51A357
Hub, Turbine Front Assembly (1st      ALL....................     72-52-05  Insp/Check-02..........       51A357
 Stage).
Hub, Turbine Rear (Stage 2).........  ALL....................     72-52-06  Insp/Check-02..........       51A357
----------------------------------------------------------------------------------------------------------------

    For Engine Manual 51A345 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, LPC Assembly...................  ALL....................     72-31-07  Insp/Check-02..........       51A370
Seal--Air, HPT, 1st Stage...........  ALL....................     72-52-19  Insp/Check-02..........       51A750
Hub, Turbine Front Assembly (1st      ALL....................     72-52-05  Insp/Check-02..........       51A750
 Stage).
Seal--Air, HPT, 2nd Stage Assembly..  ALL....................     72-52-22  Insp/Check-02..........       51A750
Hub, Turbine Rear Assembly (2nd       ALL....................     72-52-06  Insp/Check-02..........       51A750
 Stage).
----------------------------------------------------------------------------------------------------------------

    For Engine Manual 51A751 only, insert the following table:

----------------------------------------------------------------------------------------------------------------
                                                                CIR Manual
            Nomenclature                    Part Number          Section     CIR Manual Inspection    CIR Manual
----------------------------------------------------------------------------------------------------------------
Hub, LPC Assembly...................  ALL....................     72-31-07  Insp/Check-02..........       51A750
Seal--Air, HPT, 1st Stage...........  ALL....................     72-52-19  Insp/Check-02..........       51A750
Hub, Turbine Front Assembly (1st      ALL....................     72-52-05  Insp/Check-02..........       51A750
 Stage).
Seal--Air, HPT, 2nd Stage Assembly..  ALL....................     72-52-22  Insp/Check-02..........       51A750
Hub, Turbine Rear Assembly (2nd       ALL....................     72-52-06  Insp/Check-02..........       51A750
 Stage).
----------------------------------------------------------------------------------------------------------------

    (2) For the purpose 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 
manufacturer's engine manuals to either the part detail or part 
assembly level part numbers for the parts listed in the Tables 
above; 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 manufacturer's EM's.

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

Continuous Airworthiness Maintenance Program

    (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)] must maintain records of 
the mandatory inspections that result from revising the Time Limits 
Section of the EM's 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 EM's.

    (f) This amendment becomes effective on September 13, 2000.


    Issued in Burlington, Massachusetts, on June 5, 2000.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-14789 Filed 6-14-00; 8:45 am]
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