[Federal Register Volume 64, Number 109 (Tuesday, June 8, 1999)]
[Rules and Regulations]
[Pages 30379-30382]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14446]



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 Rules and Regulations
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  Federal Register / Vol. 64, No. 109 / Tuesday, June 8, 1999 / Rules 
and Regulations  

[[Page 30379]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-48-AD; Amendment 39-11187; AD 99-12-03]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT8D-1, -1A, -1B, -7, -
7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to Pratt & Whitney JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, 
-11, -15, -15A, -17, -17A, -17R, and -17AR series turbofan engines, 
that requires revisions to the engine manufacturer's Time Limits 
Section (TLS) of the JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, 
-15A, -17, -17A, -17R, and -17AR Turbofan Engines Manual to include 
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 July 8, 1999.

FOR FURTHER INFORMATION CONTACT: Christopher Spinney, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (781) 238-7175, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend pat 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to Pratt & Whitney (PW) PW JT8D-1, -
1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -
17AR series turbofan engines was published in the Federal Register on 
July 28, 1998 (64 FR 40226). 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 JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -
9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Turbofan Engines Manual, 
and, for air carriers, the approved continuous airworthiness 
maintenance program. The manufacturer of JT8D series turbofan engines 
has provided the Federal Aviation Administration (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 in this AD, 
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 supports the measures outlined in the proposed rule.
    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. Two commenters believe 
that paragraph (e) of the proposed rule is unclear and suggests that 
certain preamble language be added to it for clarity and 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 
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 this AD to 
clarify record keeping aspects of the new mandatory inspections.
    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. The 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. The FAA wants the manufacturers to have flexibility in 
managing how their manuals are structured within Air Transport 
Association code requirement.
    One commenter requests that the FAA link the conduct of mandatory 
inspections on whether the subject part was removed from an engine 
while the engine was installed on the airplane or while the engine was 
removed and in an overhaul shop. The commenter wishes to exempt those 
parts that are removed

[[Page 30380]]

from installed engines from the focused inspections. The FAA does not 
concur. The mandatory inspections are based on a single trigger. The 
trigger is a part being completely disassembled using the engine manual 
instructions (piece-part opportunity), and is not dependent on whether 
an engine is installed on the airplane. This final rule mandates that 
the definition of piece-part opportunity appears in the mandatory 
section of each affected engine manual. This final rule 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 in service 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). The 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, the 
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 the 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 ADs in the future. 
Such a notice, however, is beyond the scope of this AD and may well 
cause additional confusion rather than clarify the present situation.
    One commenter states that the proposed rule should be revised to 
allow use of Foerster Defectometer eddy current instrument for Insp-02, 
as it is currently approved for use in Insp-03. 72-33-31 Insp-02 
currently only requires that a certain probe and sensitivity standard 
be used to accomplish the inspection. The eddy current instrument to be 
used for 72-33-31 Insp-02 is specified in the PW Standard Practices 
manual, 70-37-02. The requirement for the Eddy Current signal 
instrument is that it be equivalent in performance to a Foerster 
Defectometer Model H 2.835. An eddy current signal instrument needs to 
be deemed equivalent to the Defectometer Model H 2.835 in order to be 
acceptable for 72-33-31 Insp-02. Therefore no changes are necessary to 
the AD.
    One commenter states that AD 95-10-10 compliance requirements 
relative to the JT8D Engine Manual, P/N 481672, 72-33-31 Insp-03, as 
specified in the proposed rule should be clarified. The FAA does not 
concur that a change needs to be made to the AD, but offers the 
following explanation for clarification purposes. AD 95-10-10 is 
applicable to certain serial number fan hubs installed on JT8D engines. 
While the inspections required are similar to this AD, 95-10-10 also 
contains other overhaul requirements and very specific inspection 
intervals. This AD is intended to inspect all JT8D first and second 
stage compressor disks at every piece-part opportunity. The 
requirements of both ADs must be met regardless of the overlapping 
requirements.
    One commenter states that ``XX'' in the inspection column of the 
Table in the Compliance Section under paragraph B needs clarification. 
The FAA concurs. At the time the proposed rule was published Insp-04 
was not available. Chapter 5 of the Engine Manual was revised August 1, 
1998, to include Insp-04. Inspection -XX has been changed to inspection 
number -04 for first stage compressor disks.
    One commenter states that stage 2 compressor disks in the Table 
should be repositioned for clarity and Insp-02 should be included. The 
FAA concurs. Inspection number -XX has been replaced with inspection 
number -02 for second stage compressor disks.
    One commenter states that the reference to Chapter 05-11-00 in Note 
3 of the Compliance Section is incorrect. The FAA concurs. This final 
rule has been revised to reference Chapter 05-10-00.
    No comments were received on the economic analysis contained in the 
proposed rule. Based on that analysis, the FAA has determined that the 
annual per engine cost of $420 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.
    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

[[Page 30381]]

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.

99-12-03 Pratt & Whitney: Amendment 39-11187, Docket 98-ANE-48-AD.

    Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -
7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR series 
turbofan engines, installed on but not limited to Boeing 727 and 737 
series and McDonnell Douglas DC-9 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 Time Limits Section (TLS) of the Pratt & Whitney (PW) 
JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, 
-17R, and -17AR Turbofan Engines Engine Manual (EM), part number 
481672, and for air carrier operations revise the approved 
continuous airworthiness maintenance program, by adding the 
following:

``5. Critical Life Limited Part Inspection

    A. Inspection Requirements:
    (1) This section has the definitions for individual engine piece 
parts and the inspection procedures which are necessary when these 
parts are removed from the engine.
    (2) It is necessary to do the inspection procedures of the piece 
parts in paragraph B when:
    (a) The part is removed from the engine and disassembled to the 
level specified in paragraph B and
    (b) The part has accumulated more than 100 cycles since the last 
piece part inspection, provided that the part was not damaged or 
related to the cause for its removal from the engine.
    (3) The inspections specified in this paragraph do not replace 
or make not necessary other recommended inspections for these parts 
or other parts.
    B. Parts Requiring Inspection

    Note: Piece part is defined as any of the listed parts with all 
the blades removed.

------------------------------------------------------------------------
     Engine manual description         Section          Inspection
------------------------------------------------------------------------
Hub (Disk), 1st Stage Compressor:
    491201.........................    72-33-31  -04,-02,-03
    496501.........................    72-33-31  -04,-02,-03
    504101.........................    72-33-31  -04,-02,-03
    515201.........................    72-33-31  -04,-02,-03
    594301.........................    72-33-31  -04,-02,-03
    640501.........................    72-33-31  -04,-02,-03
    640601.........................    72-33-31  -04,-02,-03
    743301.........................    72-33-31  -04,-02,-03
    749701.........................    72-33-31  -04,-02,-03
    749801.........................    72-33-31  -04,-02,-03
    750001.........................    72-33-31  -04,-02,-03
    750101.........................    72-33-31  -04,-02,-03
    778901.........................    72-33-31  -04,-02,-03
    791401.........................    72-33-31  -04,-02,-03
    791501.........................    72-33-31  -04,-02,-03
    791601.........................    72-33-31  -04,-02,-03
    791701.........................    72-33-31  -04,-02,-03
    791801.........................    72-33-31  -04,-02,-03
    806001.........................    72-33-31  -04,-02,-03
    806101.........................    72-33-31  -04,-02,-03
    817401.........................    72-33-31  -04,-02,-03
    844401.........................    72-33-31  -04,-02,-03
    845401.........................    72-33-31  -04,-02,-03
    848001.........................    72-33-31  -04,-02,-03
    848101.........................    72-33-31  -04,-02,-03
Disk, 2nd Stage Compressor:
    482502.........................    72-33-33  -02
    502502.........................    72-33-33  -02
    520602.........................    72-33-33  -02
    570302.........................    72-33-33  -02
    570402.........................    72-33-33  -02
    678202.........................    72-33-33  -02
    730202.........................    72-33-33  -02
    730302.........................    72-33-33  -02
    730402.........................    72-33-33  -02
    740502.........................    72-33-33  -02
    745702.........................    72-33-33  -02
    745902.........................    72-33-33  -02
    746002.........................    72-33-33  -02
    746802.........................    72-33-33  -02
    760402.........................    72-33-33  -02
    760502.........................    72-33-33  -02
    807502.........................    72-33-33  -02
    5002402-01.....................    72-33-33  -02
    790832 (Disk assembly).........    72-33-33  -02
------------------------------------------------------------------------

    (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 
in the 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 used in accordance with 
Sec. 21.197 and Sec. 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirement 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. Alternatively, 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 alternative 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 
alternative 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

[[Page 30382]]

to reflect the requirements in the engine manuals.
    (f) This amendment becomes effective on July 8, 1999.

    Issued in Burlington, Massachusetts, on June 1, 1999.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-14446 Filed 6-7-99; 8:45 am]
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