[Federal Register Volume 62, Number 235 (Monday, December 8, 1997)]
[Proposed Rules]
[Pages 64523-64525]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31967]
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Proposed Rules
Federal Register
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This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 62, No. 235 / Monday, December 8, 1997 /
Proposed Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-ANE-38]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series
Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This notice revises an earlier proposed airworthiness
directive (AD), applicable to Pratt & Whitney (PW) JT9D-7R4 series
turbofan engines, that would have required removal of web material at
ten bosses on the diffuser case assembly, inspections, shotpeening of
the area, and remarking the diffuser case assemblies with a new part
number. That proposal was prompted by reports of cracks in the aft
corners of the bosses. This action revises the proposed rule by adding
initial and repetitive on-wing eddy current inspections (ECI) of the
affected bosses for cracks, and replacement, if found cracked, with
serviceable parts. In addition, this action revises the initial
accomplishment time for the previously proposed actions. Finally, this
action adds further etches, fluorescent penetrant inspections (FPIs),
x-ray inspections, and shotpeening to the shop requirements, and
provides an optional terminating action in the form of a redesigned
diffuser case. The actions specified by this proposed AD are intended
to prevent diffuser case assembly rupture, which could result in an
uncontained engine failure, engine fire, and damage to the aircraft.
DATES: Comments must be received by February 6, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 95-ANE-38, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ad-
[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.
The service information referenced in the proposed rule may be
obtained from Pratt & Whitney, Publications Department, Supervisor
Technical Publications Distribution, M/S 132-30, 400 Main St., East
Hartford, CT 06108; telephone (860) 565-7700, fax (860) 565-4503. This
information may be examined at the FAA, New England Region, Office of
the Assistant Chief 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:
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 95-ANE-38.'' 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 Assistant Chief Counsel,
Attention: Rules Docket No. 95-ANE-38, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an airworthiness directive (AD), applicable to
Pratt & Whitney (PW) JT9D-7R4 series turbofan engines, was published as
a notice of proposed rulemaking (NPRM) in the Federal Register on
August 23, 1995 (60 FR 43730). That NPRM would have required removing
webs of material at ten bosses on the diffuser case assembly,
performing a fluorescent penetrant inspection (FPI) and x-ray
inspection of the reworked area, performing furnace stress relief if a
local stress relief had been previously accomplished, shotpeening the
reworked area, and remarking the diffuser case assemblies with a new
part number. That NPRM was prompted by reports of cracks at the aft
corners of bosses on the diffuser case assembly. No engine failures
have resulted from these cracks. The cracks occur in webs of material
at 10 diffuser case bosses that were a result of a machining operation
during original manufacture. The webs of material create stress
concentrations that can cause a crack to start. That condition, if not
corrected, could result in diffuser case assembly rupture, which could
result in an uncontained engine failure, engine fire, and damage to the
aircraft.
Since the issuance of that NPRM, the FAA received three comments
regarding the actions proposed by this AD.
One commenter states basic concurrence with the intent of the AD,
but recommends a change in the accomplishment time, from the next shop
visit, not to exceed 6,000 cycles in service (CIS) after the effective
date of this AD, to the next diffuser module
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disassembly after the effective date of this AD. The commenter states
that the original accomplishment time causes an undue scheduling
burden, and estimates that an additional $469,608 will be incurred
without the revision to the accomplishment time. The FAA concurs. The
FAA has revised the accomplishment time, and has added initial and
repetitive on-wing and shop eddy current inspections (ECI) of the
bosses to mitigate any additional safety risk incurred by the extension
of the accomplishment time.
One commenter recommends a change to the work hours estimate in the
economic analysis. The commenter states that 44 work hours of labor are
necessary to perform the actions required by this AD, instead of the 20
work hours specified in the NPRM, and indicates that 44 work hours is
more consistent with the maintenance environment of airlines and repair
facilities. The FAA concurs, and has revised the economic analysis
accordingly, but has increased the work hours estimate further in this
supplemental NPRM to include the time required to accomplish the
additional actions proposed in this supplemental NPRM.
In addition, since issuance of the NPRM, the FAA has determined the
need to enhance the AD by adding further etches, fluorescent penetrant
inspections (FPIs), x-ray inspections, and shotpeening to the shop
requirements. The FAA estimates that an additional two hours of labor
will be necessary to access and perform the enhanced inspection of the
diffuser case. The FAA also has determined the need to clarify, based
on overhaul shop concerns regarding repairable diffuser cases, that
cracks under the rail are acceptable as long as total weld bead length
is less than 1.5 inches. This supplemental NPRM has been revised
accordingly to incorporate these changes.
Finally, this supplemental NPRM references PW Service Bulletin (SB)
No. JT9D-7R4-72-527, Revision 3, dated April 16, 1997, Revision 2,
dated July 12, 1996, and Revision 1, dated May 3, 1996, that describes
the on-wing ECIs required by this AD, and SB No. JT9D-7R4-72-469,
Revision 3, dated January 24, 1996, that describes the new shop
procedures required by this AD. In addition, installation of diffuser
case, part number 815736, in accordance with the requirements of PW SB
No. JT9D-7R4-72-533, dated August 29, 1996, constitutes terminating
action for this AD.
Since these changes expand the scope of the originally proposed
rule, the FAA has determined that it is necessary to reopen the comment
period to provide additional opportunity for public comment.
There are approximately 690 engines of the affected design in the
worldwide fleet. The FAA estimates that 137 engines would be affected
by this proposed AD, that it would take approximately 46 work hours per
engine to accomplish the proposed actions, and that the average labor
rate is $60 per work hour. Based on these figures, the total cost
impact of the proposed AD on U.S. operators is estimated to be
$378,120.
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 No. 95-ANE-38.
Applicability: Pratt & Whitney (PW) JT9D-7R4 series turbofan
engines, installed on but not limited to Airbus A300, A310 series,
and Boeing 747, 767 series aircraft.
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 (g) 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 diffuser case assembly rupture, which could result in
an uncontained engine failure, engine fire, and damage to the
aircraft, accomplish the following:
(a) For assembled diffuser case assembly, Part Numbers (P/Ns)
789996, 789996-002, 789996-003, 790541, 790541-002, 790541-003,
798379, 798379-003, 798379-004, 5000366-002, 5000366-021, 5000366-
022, 5004770-01, 5004770-022, and 5004770-023, perform initial on-
wing eddy current inspection (ECI) or initial and repetitive
fluorescent penetrant inspection (FPI) or ECI shop inspections of
the diffuser case bosses in accordance with PW Service Bulletin (SB)
No. JT9D-7R4-72-527, Revision 3, dated April 16, 1997, or Revision
2, dated July 12, 1996, or Revision 1, dated May 3, 1996, within 250
cycles in service (CIS) after the effective date of this AD, as
follows:
(1) For assembled diffuser cases in the shop, that have not been
previously inspected in accordance with any one of the requirements
of the SBs cited in paragraph (a) of this AD, perform an initial FPI
or ECI of both rear corners of all 10 diffuser case mounting bosses
and 2 case mount pads in accordance with any one of the SBs cited in
paragraph (a) of this AD, or,
(i) If cracks are found, perform repairs in accordance with the
applicable Engine Manual, Chapter/Section 72-41-02, Repair-28.
(ii) Thereafter, perform inspections within 650 CIS since last
inspection, in accordance with any one of the SBs cited in paragraph
(a) of this AD.
(2) For assembled diffuser cases that are installed on-wing,
that have not been previously inspected in accordance with any of
the requirements of this AD, perform an initial ECI of both rear
corners of boss six, located at the six o'clock position, in
accordance with any one of the SBs cited in paragraph (a) of this
AD:
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(i) If a crack indication is found, borescope or FPI the area
where the crack was indicated, in accordance with any one of the SBs
cited in paragraph (a) of this AD. Depending on the crack size,
accomplish the following:
(A) The diffuser case may continue in service provided it is
inspected at intervals not to exceed 50 CIS since last borescope
inspection, if the circumferential crack dimension ``B'', is less
than 0.5 inches long, and the axial crack dimension ``A'' is less
than 0.8 inches long, in accordance with any one of the SBs cited in
paragraph (a) of this AD.
(B) The diffuser case may continue in service for a maximum of 5
CIS, if the axial crack dimension ``A'' is equal to or greater than
0.8 inches but less than or equal to 1.0 inch, in accordance with
any one of the SBs cited in paragraph (a) of this AD.
(C) Remove from service prior to further flight the diffuser
case when the axial crack dimension ``A'' is greater than 1.0 inch,
in accordance with any one of the SBs cited in paragraph (a) of this
AD.
(ii) Diffuser cases with no cracks at boss six, perform an ECI
at intervals not to exceed 650 CIS since the last boss 6 inspection,
in accordance with any one of the SBs cited in paragraph (a) of this
AD.
(b) At the next diffuser module disassembly when all hardware is
stripped off the diffuser case, but not to exceed 6,000 CIS after
the effective date of this AD, inspect diffuser cases, P/Ns 790541,
798379, 789996, 5004770-01, or 5000366-02, for existence of web
material at ten boss locations, in accordance with PW SB No. JT9D-
7R4-72-469, Revision 3, dated January 24, 1996.
(1) Rework the diffuser case assembly in accordance with PW SB
No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996. This rework
removes web material at 10 boss locations.
(2) Perform an etch and an ultra-high fluorescent penetrant
inspection (FPI) of the reworked areas in accordance with PW SB No.
JT9D-7R4-72-469, Revision 3, dated January 24, 1996, to ensure that
there are no crack indications.
(3) If a crack indication is discovered, repair, and perform an
ECI and an FPI in accordance with Engine Manual Section 72-41-02,
Repair-28, or remove the diffuser case from service and replace with
a serviceable part.
(4) Perform an x-ray inspection of the reworked areas (all 10
boss locations and 2 mount pad locations) in accordance with PW SB
No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996, to ensure
that there are no crack indications. Additionally, the x-ray
inspection is performed to assure that there are no cracks,
incomplete fusion, incomplete penetration, voids, porosity, or
inclusions from previous local weld repairs. If any of these defects
are discovered, repair per PW JT9D-7R4 Engine Manual, Section 72-41-
02, Repair-28, or remove the diffuser case from service and replace
with a serviceable part.
(5) Determine if local stress relief was performed previously,
and if weld repairs have been performed at any of the boss locations
described in the above SB, through reviewing maintenance records. If
maintenance records cannot be located, or maintenance records
indicate that a weld repair with no stress relief or a weld repair
with a local stress relief that has been performed at any of the 10
boss locations or 2 mount pad locations, perform furnace stress
relief and FPI of the diffuser case assemblies in accordance with PW
SB No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996.
(6) Shotpeen the reworked areas in accordance with PW SB No.
JT9D-7R4-72-469, Revision 3, dated January 24, 1996.
(7) Remark the diffuser case assembly with a new part number in
accordance with PW SB No. JT9D-7R4-72-469, Revision 3, dated January
24, 1996.
(c) At the next shop visit, but not to exceed 6,000 CIS after
the effective date of this AD, for diffuser case assembly, P/Ns
790541-002, 790541-003, 798379-003, 798379-004, 789996-002, 789996-
003, 5000366-021, 5000366-022, 5004770-022, and 5004770-023, that
have been previously reworked to remove web material at any boss
locations prior to the effective date of this AD in accordance with
the original issue of PW SB No. JT9D-7R4-72-469, dated October 2,
1992, accomplish the following:
(1) Unless maintenance records indicate that x-ray inspections
were performed at the last shop visit where diffuser case repairs
were accomplished at the 10 boss locations, prior to the effective
date of this AD, in accordance with PW JT9D-7R4 Engine Manual,
Section 72-41-02, Repair-28, perform an x-ray inspection of all 10
boss locations and 2 mount pad locations in accordance with the x-
ray requirements of PW JT9D-7R4 Engine Manual, Section 72-41-02,
Repair-28.
(2) Determine if any previous weld repairs have been performed
at any of the boss locations described in the above SB through
reviewing maintenance records. If maintenance records cannot be
located, or maintenance records indicate that a weld repair with no
stress relief or with a local stress relief has been performed at
any of the boss locations, perform furnace stress relief, FPI, and
shotpeen diffuser case assemblies in accordance with PW SB No. JT9D-
7R4-72-469, Revision 3, dated January 24, 1996.
(d) For the purpose of this AD, shop visit is defined as
separation of diffuser case at ``K'' and ``M'' flanges.
(e) For the purpose of this AD, an assembled diffuser case in
the shop is defined as a diffuser case either mounted or dismounted
from the engine, but with external hardware removed to perform the
inspections.
(f) Installation of diffuser case, P/N 815736, in accordance
with the requirements of PW SB No. JT9D-7R4-72-533, dated August 29,
1996, constitutes terminating action for this AD.
(g) 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 Manager, Engine Certification Office.
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, 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.
(h) 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 aircraft to a location where
the requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on November 28, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 97-31967 Filed 12-5-97; 8:45 am]
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