[Federal Register Volume 64, Number 109 (Tuesday, June 8, 1999)]
[Rules and Regulations]
[Pages 30382-30384]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14447]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket 98-ANE-43-AD; Amendment 39-11188; Ad 99-12-04]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT8D-200 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-200 series turbofan engines, that
requires revisions to the engine manufacturer's Time Limits Section
(TLS) of the JT8D-200 Turbofan Engine 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 part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to Pratt & Whitney (PW) JT8D-200
series turbofan engines was published in the Federal Register on July
28, 1998 (63 FR 40216). 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 PW JT8D-200 Turbofan Engine Manual, and,
for air carriers, the approved continuous airworthiness maintenance
program. The manufacturer of JT8D-200 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.
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 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.
One commenter suggests 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 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 time-since-new
(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
[[Page 30383]]
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 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 suggested that the parts requiring focused inspection
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 states that a ``spot focused'' fluorescent-penetrant
inspection (FPI) should be performed in the rivet area of the fan hub
instead of removing rivets, the air seal, and the compressor duct to
inspect the fan hub. The commenter believes that rivet removal and
replacement may induce stresses and cause cracks. The FAA does not
concur. Inspection of the entire fan hub (i.e., bore, all holes, fillet
radii, rim slot bottom, upper lug surface, pressure face of dovetail
slots) is needed to detect all possible crack indications. Although few
cracks have been detected thus far, there is concern that other high
stress areas (e.g. dovetail slots) may be affected. Furthermore,
removal of the assembled parts (air seal and compressor duct) will
provide assurance that liquids for inspection and cleaning will not
become entrapped in the titanium hub.
One commenter states that the phrase ``by or related to the cause
of its removal from the engine'' should be added for clarification to
paragraph (2)(b) of Inspection Requirements, paragraph A, in the
Compliance Section. The FAA concurs and the phrase has been added.
One commenter states that the affected assembly part number (P/N)
in the Compliance Section, paragraph B, Parts Requiring Inspection
Table, is in error and should be 5000421-01. The FAA concurs and the P/
N has been revised.
One commenter states that AD 97-17-04 compliance requirements
relative to the JT8D Engine Manual, P/N 773128, 72-33-31 Insp-02, 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. The inspection
requirements of AD 97-17-04 remain intact and are not affected by this
AD. While the inspection techniques are similar, this AD will require
inspections at every piece-part opportunity without having to remove
bushings. AD 97-17-04 requires inspections with bushings removed at
fixed inspection intervals depending on part serial number.
One commenter states that an existing alternative method of
compliance (AMOC) for removal of C1 hub bushings prior to eddy current
inspection should be allowed for this AD. The FAA does not concur.
Because this AD does not require the removal of bushings at every
piece-part opportunity, no AMOC for an alternate bushing removal
procedure is required.
One commenter states that the PW JT8D-200 Turbofan Engine Manual
section reference in the Parts Requiring Inspection table is in error
and should read 72-33-31. The FAA concurs and the table has been
revised.
No comments were received on the economic analysis contained in the
proposed rule. Based on the analysis, the FAA has determined that the
annual per engine cost of $240 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 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:
99-12-04 Pratt & Whitney: Amendment 39-11188. Docket 98-ANE-43-AD.
Applicability Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C,
and -219 series turbofan engines, installed on but not limited to
McDonnell Douglas MD80 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
[[Page 30384]]
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, alternation, 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 Limit Section (TLS) of the PW JT8D-200 Engine Manual
(EM), Part Number 773128, and for air carrier operations revise the
approved continuous airworthiness maintenance program, by adding the
following:
``3. 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 is not damaged or
related to the cause of its removal from the engine.
(3) The inspections specified in this section do not replace or
make unnecessary 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.
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Description Section Inspection
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Hub (Disk), 1st Stage Compressor:
5000501-01 (Hub detail).......... 72-33-31 -02,-03
5000421-01 (Hub assembly)........ 72-33-31 -02,-03''
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(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 TLS of the PW JT8D-
200 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 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.
(b) 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. 99-14447 Filed 6-7-99; 8:45 am]
BILLING CODE 4910-13-M
