AD Amdt-39-11118

[Federal Register Volume 64, Number 70 (Tuesday, April 13, 1999)]
[Rules and Regulations]
[Pages 17954-17956]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 99-8862]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-47-AD; Amendment 39-11118; AD 99-08-12]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D 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 Engine Time Limits section in the Engine 
Manual (EM) for Pratt & Whitney (PW) JT9D 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 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: Effective May 13, 1999.

ADDRESSES: The information referenced in this AD 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: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7130, 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 JT9D series 
turbofan engines was published in the Federal Register on July 28, 1998 
(63 FR 40220). That action proposed to require revisions to the Engine 
Time Limits section in the Engine Manual (EM) for Pratt & Whitney JT9D 
series turbofan engines to include required enhanced inspection of 
selected critical life-limited parts at each piece-part exposure. That 
action also proposed to require an air carrier's approved continuous 
airworthiness maintenance program to incorporate these inspection 
procedures.
    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 notes that the JT9D manual used by the operator [part 
number (P/N) 770407] to maintain JT9D-7A and -7J engines is not 
included in paragraph (a), which lists the JT9D manuals which require 
revisions to the Engine Time Limits Section by P/N. The FAA concurs. 
Several engine manuals applicable to certain JT9D-7 models are 
customized for operators. Part numbers for these engine manuals were 
inadvertently omitted from the proposed rule. Corrections for the 
engine manual referenced by the commentor and for other engine manuals 
have been included in this AD.
    Several commenters suggested that the tables used to specify those 
parts requiring mandatory inspections be given standardized formats and 
that the parts be identified by ``all'' rather than by specific part 
number. The FAA does not concur. FAA intentionally allowed each 
manufacturer to choose a format that fits their products manual. 
Identification of parts requiring mandatory inspections has been 
accomplished by either part number identification or use of the word 
``all''. Part number identification was chosen by some manufacturers 
since the processes and procedures needed to conduct new inspections 
were not yet developed for all parts of a certain type, i.e., fan 
disks/hubs. FAA wants the manufacturers to have flexibility in managing 
how their manuals are structured within Air Transport Association code 
requirement and does not consider mandating matters of format 
appropriate.
    Several commenters ask that the FAA clarify the record keeping 
aspects of the mandatory inspections resulting from the required 
changes to the Original Equipment Manufacturer's manual and operator's 
continuous airworthiness maintenance program. One commenter believes 
that paragraph (e) of the NPRM is unclear and suggests that it be 
revised by eliminating the word ``or'' from the first sentence and 
beginning a second sentence with ``In lieu of the record. * * *'' Two 
commenters state that the AD should be revised to clearly specify which 
types of maintenance records must be retained (i.e., inspection 
results, defect reporting requirements, date of performed maintenance, 
signature of the person performing the maintenance). These commenters 
believe that these revisions are necessary in order to avoid potential 
differences in interpretation between the air carriers and the FAA. 
And, one commenter states that the AD should clarify that there is no 
need for a special form to comply with the AD record keeping 
requirements. The FAA concurs in part. Generally, record keeping 
requirements are addressed in other regulations and this AD does not

[[Page 17955]]

change those requirements. In order to allow flexibility from operator 
to operator, the FAA does not concur that the AD itself specify the 
precise nature of the records that will result from the required 
changes to the manufacturer's manual and operator's maintenance 
program. The FAA has, however, revised Paragraph (e) of the final rule 
to clarify record keeping aspects of the new mandatory inspections.
    One commenter requested that the FAA link the conduct of mandatory 
inspections with the subject part's removal from an engine either on-
wing or in an overhaul shop. The FAA does not concur. Mandatory 
inspections are based on a single trigger, which is a part being 
completely disassembled per the engine manual instructions (piece-part 
opportunity), and are not dependent on an engine's state of 
installation. This AD mandates that the definition of piece-part 
opportunity appear in the mandatory section of each affected engine 
manual. This AD further mandates that an operator's continuous 
airworthiness maintenance program be modified to capture those engine 
manual changes.
    Several commenters suggest that the 100 cycle inservice inspection 
waiver provided in the piece-part opportunity definition was too low 
and could not be justified from a crack growth standpoint or that 
language be added to the requirements adding a minimum cycles in 
service threshold after which mandatory inspections would be 
applicable. The FAA does not concur. The 100 cycle waiver is intended 
to allow short term alleviation from mandatory inspections for a part 
recently inspected in accordance with the engine manual requirements. 
It was specifically aimed at disassembled parts removed from an engine 
following a test cell reject or some other occurrence that caused the 
parts removal shortly after successful completion of mandatory 
inspections. Waiver of mandatory inspections in this instance also 
requires that the part was not damaged or related to the cause for its 
removal from the engine. Mandatory inspections are also required on 
fully disassembled parts regardless of time-since-new (TSN). FAA is 
aware that cracks can be missed during part inspections and that each 
time a part is processed through an inspection line, the probability of 
detecting a crack is increased. Commonly used on-condition maintenance 
plans make it likely that a given part could be returned to service for 
thousands of cycles without the need for additional focused inspection. 
Recognizing two opposing aspects of part removal and inspection, i.e., 
a need for a brief exemption period following conduct of mandatory 
inspections and the benefits of increased frequency of inspection, FAA 
established the 100 cycle threshold. No consideration for crack growth 
time was given in the choice of this number nor was TSN considered as a 
possible reason for exempting parts from focused inspection. It is 
based strictly on keeping the frequency of mandatory inspection as high 
as practical and therefore increasing the probability of crack 
detection while providing a brief window of exemption from mandatory 
inspection if certain conditions are met. Therefore, the 100 cycle 
limit will remain in the compliance section of the AD and no exemption 
will be allowed for low TSN parts.
    One commenter states that the mandatory manual chapters were 
modified to require new inspection requirements prior to issuance of 
the final rule AD and that FAA should provide written notification to 
Flight Standards Offices that the inspections proposed in the proposed 
rule are not mandatory until the establishment of an effectivity date 
in a published final rule AD. Some confusion between Operators, 
Manufacturers and Principal Maintenance Inspectors was created when the 
mandatory manual sections were modified prior to the release of a final 
rule AD. The FAA concurs in part. The manuals were modified prior to 
issuance of the final rule to minimize implementation delays from 
lengthy original equipment manufacturer EM revision cycles. FAA will 
attempt a higher level of coordination of timing the manual revisions 
so that the revisions follow final rule AD's in the future. However, to 
avoid additional confusion with the currently proposed changes, FAA 
will not issue written notice to the Flight Standards Offices.
    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 $284 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 as proposed.
    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.

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:

99-08-12  Pratt & Whitney: Amendment 39-11118. Docket 98-ANE-47-AD.

    Applicability: Applicability: Pratt & Whitney (PW) JT9D-3A, -7, 
-7H, -7A, -7AH, -7F, -7J, -20J, -59A, -70A, -7Q, -7Q3, -7R4D, -
7R4D1, -7R4E, -7R4E1, -7R4G2, -7R4H1, and 7R4E4 series turbofan 
engines, installed on but not limited to Boeing 747 and 767 series, 
McDonnell Douglas DC-10 series, and Airbus A300 and A310 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

[[Page 17956]]

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 Engine Time Limits Section (TLS) of the manufacturer's 
Engine Manual (EM), JT9D Part Numbers 646028, 754459, 770407, 
770408, 777210, 785059, 785058, 789328, as appropriate, 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 
applicable manual provisions:

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                                                   Inspect per
          Part Nomenclature             Part No.      manual                       Inspection
                                         (P/N)       section
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Fan hub (Assy. P/N 648621)..........       648501     72-31-04  Inspection-02.
Fan hub (Assy. P/N 665321)..........       648501     72-31-04  Inspection-02.
Fan hub (Assy. P/N 665321, 719127,         666101     72-31-04  Inspection-02.
 778621).
Fan hub (Assy. P/N 678541, 726641,         690501     72-31-04  Inspection-02.
 778631).
Fan hub (Assy. P/N 726941)..........       734901     72-31-04  Inspection-02.
Fan hub (Assy. P/N-732721)..........       745401     72-31-00  Heavy Maintenance-Check.
Fan hub (Assy. P/N 804221)..........       745401     72-31-00  Heavy Maintenance-Check.
Fan hub (Assy. P/N 5001331-01)......   5001701-01     72-31-00  Inspection-03.
----------------------------------------------------------------------------------------------------------------

    (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 
manufacturers engine manual to either part number listed in the 
table 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 Sec. 43.16 of the Federal 
Aviation Regulations (14 CFR 43.16), these mandatory inspections 
shall be performed only in accordance with the Engine TLS of the PW 
JT9D EM.
    (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 
Secs. 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 Engine 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. 99-8862 Filed 4-12-99; 8:45 am]
BILLING CODE 4910-13-U