[Federal Register Volume 63, Number 214 (Thursday, November 5, 1998)]
[Proposed Rules]
[Pages 59743-59746]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-29603]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-66-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This proposal would require 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 proposal would also require an air carrier's 
approved continuous airworthiness maintenance program to incorporate 
these inspection procedures. Air carriers with an approved continuous 
airworthiness maintenance program would be allowed to either maintain 
the records showing the current status of the inspections using the 
record keeping system specified in the air carrier's maintenance 
manual, or establish an acceptable alternate method of record keeping. 
This proposal is prompted by an FAA study of in-service events 
involving uncontained failures of critical rotating engine parts which 
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 proposed 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: Comments must be received by February 3, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 98-ANE-66-AD, 12 New England 
Executive Park,

[[Page 59744]]

Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. 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.

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 filed in 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 98-ANE-66-AD.'' 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. 98-ANE-66-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    A recent FAA study analyzing 15 years of accident data for 
transport category airplanes identified several failure mode root 
causes that can result in serious safety hazards to transport category 
airplanes. This study identified uncontained failure of critical life-
limited rotating engine parts as the leading engine-related safety 
hazard to airplanes. Uncontained engine failures have resulted from 
undetected cracks in rotating parts that initiated and propagated to 
failure. Cracks can originate from causes such as unintended excessive 
stress from the original design, or they may initiate from stresses 
induced from material flaws, handling damage, or damage from machining 
operations. The failure of rotating parts can present a significant 
safety hazard to the airplanes by release of high energy fragments that 
could injure passengers or crew by penetration of the cabin, damage 
flight control surfaces, sever flammable fluid lines, or otherwise 
compromise the airworthiness of the airplane.
    Accordingly, the FAA has developed an intervention strategy to 
significantly reduce uncontained engine failures. This intervention 
strategy was developed after consultation with industry and will be 
used as a model for future initiatives. This intervention strategy is 
to conduct enhanced, nondestructive inspections of fan disks which 
could most likely result in a safety hazard to the airplane in the 
event of a disk fracture. The need for additional rule making is also 
being considered by the FAA. Future ADs may be issued introducing 
additional intervention strategies to further reduce or eliminate 
uncontained engine failures.
    Properly focused enhanced inspections require identification of the 
parts whose failure presents the highest safety hazard to the airplane, 
identifying the most critical features to inspect on these parts, and 
utilizing inspection procedures and techniques that improve crack 
detection. The FAA, with close cooperation of the engine manufacturers, 
has completed a detailed analysis that identifies the most safety 
significant parts and features, and the most appropriate inspection 
methods.
    Critical life-limited high energy rotating parts are currently 
subject to some form of recommended crack inspection when exposed 
during engine maintenance or disassembly. As a result of this AD, the 
inspections currently recommended by the manufacturer will become 
mandatory for those parts listed in the compliance section. 
Furthermore, the FAA intends that additional mandatory enhanced 
inspections resulting from this AD serve as an adjunct to the existing 
inspections. The FAA has determined that the enhanced inspections will 
significantly improve the probability of crack detection while the 
parts are disassembled during maintenance. All mandatory inspections 
must be conducted in accordance with detailed inspection procedures 
prescribed in the manufacturer's Engine Cleaning, Inspection, and 
Repair (CIR) manuals.
    Additionally, this AD allows for air carriers operating under the 
provisions of 14 CFR part 121 with an FAA-approved continuous 
airworthiness maintenance program, and entities with whom those air 
carriers make arrangements to perform this maintenance, to verify 
performance of the enhanced inspections by retaining the maintenance 
records that include the inspections resulting from this AD, provided 
that the records include the date and signature of the person 
performing the maintenance action. These records must be retained with 
the maintenance records of the part, engine module, or engine until the 
task is repeated. This will establish a method of record preservation 
and retrieval typical to those in existing continuous airworthiness 
maintenance programs. Instructions must be included in an air carrier's 
maintenance manual providing procedures on how this record preservation 
and retrieval system will be implemented and integrated into the air 
carrier's record keeping system.
    For engines or engine modules that are approved for return to 
service by an authorized FAA-certificated entity and that are acquired 
by an operator after the effective date of this AD, the mandatory 
enhanced inspections need not be accomplished until the next piece-part 
opportunity. For example, there is no need for an operator to 
disassemble to piece-part level an engine or module returned to service 
by an FAA-certificated facility simply because that engine or module 
was previously operated by an entity not required to comply with this 
AD. Furthermore, the FAA intends for operators to perform the enhanced 
inspections of these parts at the next piece-part opportunity following 
the initial acquisition, installation, and removal of the part 
following the effective date of this AD. For piece parts that have not 
been approved for return to service prior to the effective date of this 
AD, the FAA does intend that the mandatory enhanced inspections 
required by this AD be performed before such parts are approved for 
return to service. Piece parts that have been approved for return to 
service prior to the effective date of this AD may be installed; 
however,

[[Page 59745]]

enhanced inspection will be required at the next piece-part 
opportunity.
    This proposal would require, within the next 30 days after the 
effective date of this AD, revisions to the Time Limits Section (TLS) 
of the Engine Manuals for PW4000 series turbofan engines, and, for air 
carriers, the approved continuous airworthiness maintenance program. 
Pratt & Whitney, the manufacturer of PW4000 series turbofan engines, 
used on 14 CFR part 25 airplanes 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. The enhanced inspections resulting from this AD 
will be conducted at piece-part opportunity, as defined below in the 
compliance section, rather than specific time inspection intervals.
    There are approximately 1,900 engines of the affected design in the 
worldwide fleet. The FAA estimates that 450 engines installed on 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 8 work hours for the fan disk inspection. 
The average labor rate is $60 per work hour. Based on these figures, 
and using recent shop visit rate data, the total cost impact of the 
proposed AD on U.S. operators is estimated to be $70,000 per year.
    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 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 adding the following new 
airworthiness directive:

Pratt & Whitney: Docket 98-ANE-66-AD.
    Applicability: 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, 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) 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:
    (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:

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                                                                                Manual                    CIR
                 Part nomen                                P/N                 section     Inspection    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 done 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

[[Page 59746]]

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) The records of the mandatory inspections required as a 
result of revising the Time Limits section of the PW4000 series 
Engine Manuals and the air carrier's continuous airworthiness 
maintenance program as provided by paragraph (a) of this AD shall be 
maintained by FAA-certificated air carriers which have an approved 
continuous airworthiness maintenance program in accordance with the 
record keeping system currently specified in their manual required 
by sections 121.369 of the Federal Aviation Regulations (14 CFR 
121.369); or, in lieu of the record showing the current status of 
each mandatory inspection required by sections 121.380(a)(2)(vi) of 
the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)), 
certificated air carriers may establish an approved alternate 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 sections 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.

    Note 3: These record keeping requirements apply only to the 
records used to document the mandatory inspections required as a 
result of revising the Time Limits section of the PW4000 series 
Engine Manuals as provided in paragraph (a) of this AD, and do not 
alter or amend the record keeping requirements for any other AD or 
regulatory requirement.

    Issued in Burlington, Massachusetts, on October 30, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-29603 Filed 11-4-98; 8:45 am]
BILLING CODE 4910-13-U