[Federal Register Volume 60, Number 163 (Wednesday, August 23, 1995)]
[Proposed Rules]
[Pages 43730-43732]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-20851]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-ANE-38]
Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series
Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to Pratt & Whitney (PW) JT9D-7R4
series turbofan engines. This proposal would require 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. This proposal is prompted by reports of cracks
in the aft corners of the bosses. The actions specified by the 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 October 23, 1995.
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 be inspected at
this location between 8 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, 400 Main St., East Hartford, CT 06108.
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: John Fisher, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7149, fax (617) 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
The Federal Aviation Administration (FAA) has received reports of
cracks at the aft corners of bosses on the diffuser case assembly on
Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. No engine
failures have resulted from these cracks. The cracks occur in webs of
material at ten bosses that were a result of a machining operation
during original
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manufacture. The webs of material create stress concentrations that can
cause a crack to start. Removal of this web material will provide local
stress relief and prevent the initiation of cracks at the aft corners
of the bosses. This 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.
The FAA has reviewed and approved the technical contents of PW
Service Bulletin No. JT9D-7R4-72-469, Revision 2, dated April 25, 1994,
that describes procedures for removing the web of material from ten
bosses on the diffuser case assembly, performing a fluorescent
penetrant inspection (FPI) and x-ray inspection of the reworked area,
and shotpeening the reworked area. In addition, for diffuser case
assemblies that have been previously weld-repaired but no records can
be located to indicate that they have undergone furnace stress relief,
or for diffuser case assemblies with weld repairs that have only been
locally stress relieved, this SB describes procedures for performing
furnace stress relief of these previously welded diffuser case
assemblies to ensure that there is sufficient hardness.
Since an unsafe condition has been identified that is likely to
exist or develop on other engines of this same type design, the
proposed AD would require removing webs of material at ten bosses on
the diffuser case assembly, performing an 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. The
actions would be required to be accomplished in accordance with the
service bulletin described previously.
The FAA estimates that 127 engines installed on aircraft of U.S.
registry would be affected by this proposed AD, that it would take
approximately 20 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 $152,400.
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 USC 106(g), 40101, 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 series and A310
series, and Boeing 747 series and 767 series aircraft.
Note: 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 use the
authority provided in paragraph (c) to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition, or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any engine from the applicability of this AD.
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) At the next engine shop visit, but not later than 6,000
cycles in service after the effective date of this AD, whichever
occurs first, inspect the diffuser case assembly, Part Numbers (P/N)
790541, 798379, 789996, 5004770-01, or 5000366-02, for existence of
web material at ten boss locations, in accordance with PW Service
Bulletin (SB) No. JT9D-7R4-72-469, Revision 2, dated April 25, 1994.
(1) For diffuser case assemblies that incorporate web material
at any boss locations described in the above SB, accomplish the
following:
(i) Rework the diffuser case assembly in accordance with PW SB
No. JT9D-7R4-72-469, Revision 2, dated April 25, 1994. This rework
removes web material at ten boss locations.
(ii) Perform a fluorescent penetrant inspection (FPI) of the
reworked areas in accordance with PW SB No. JT9D-7R4-72-469,
Revision 2, dated April 25, 1994, to ensure that there are no crack
indications. If a crack indication is discovered, repair per Engine
Manual Section 72-41-02, Repair 28, or remove the diffuser case from
service and replace with a serviceable part.
(iii) Perform an x-ray inspection of the reworked areas in
accordance with PW SB No. JT9D-7R4-72-469, Revision 2, dated April
25, 1994, 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.
(iv) 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 ten boss locations, perform furnace stress relief and FPI
diffuser case assemblies in accordance with PW SB No. JT9D-7R4-72-
469, Revision 2, dated April 25, 1994.
(v) Shotpeen the reworked areas in accordance with PW SB No.
JT9D-7R4-72-469, Revision 2, dated April 25, 1994.
(vi) Remark the diffuser case assembly with a new part number in
accordance with PW SB No. JT9D-7R4-72-469, Revision 2, dated April
25, 1994.
(2) For diffuser case assemblies 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:
(i) Unless maintenance records indicate that x-ray inspections
were performed at ten
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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 ten boss locations in accordance with the x-
ray requirements of PW JT9D-7R4 Engine Manual, Section 72-41-02,
Repair 28.
(ii) 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 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 2,
dated April 25, 1994.
(b) For the purpose of this AD, an engine shop visit is defined
as when the ``K'' and ``M'' flanges are separated so that the
diffuser case is removed.
(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 Manager, Engine Certification Office. The
request should be forwarded through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Engine Certification Office.
Note: 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 aircraft to a location where
the requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on August 15, 1995.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 95-20851 Filed 8-22-95; 8:45 am]
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