Airworthiness Directives; Pratt & Whitney (P&W) Division Turbofan Engines, 60288-60296 [2012-23791]
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Federal Register / Vol. 77, No. 192 / Wednesday, October 3, 2012 / Rules and Regulations
Alert Service Bulletin 777–32A0082, dated
December 9, 2010. Do all applicable related
investigative and corrective actions before
further flight.
(h) Definition
For the purposes of this AD, chicken-wire
cracks are defined as cracks that occur when
stress created in the chrome deposit during
plating are relieved. The cracks are evident
in the deposited chrome when viewed from
a perpendicular plane as a pattern similar to
chicken wire. Crack size can vary with
plating conditions.
(i) Exceptions to Service Information
(1) Where Boeing Alert Service Bulletin
777–32A0082, dated December 9, 2010,
specifies a compliance time after the original
issue date of that service bulletin, this AD
requires compliance within the specified
compliance time after the effective date of
this AD.
(2) Where Boeing Alert Service Bulletin
777–32A0082, dated December 9, 2010,
specifies use of Royco 11MS grease for the
lubrication required by paragraph (g) of this
AD, this AD also allows use of MIL–PRF–
32014 grease.
(j) Optional Actions for Compliance With
Paragraph (g) of This AD
(1) Doing the detailed and magnetic
particle inspections in accordance with Part
2 of the Accomplishment Instructions of
Boeing Special Attention Service Bulletin
777–32–0080, dated July 10, 2008; or Boeing
Special Attention Service Bulletin 777–32–
0080, Revision 1, dated April 16, 2009; is
considered acceptable for compliance with
the inspections of the center axle of the MLG
required by paragraph (g) of this AD.
(2) Accomplishment of all applicable
actions specified in and in accordance with
the Accomplishment Instructions of Boeing
Service Bulletin 777–32–0085, dated April
14, 2011, is considered acceptable for
compliance with the requirements of
paragraph (g) of this AD.
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(k) Special Flight Permit
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 airplane to
a location where the airplane can be
modified (if the operator elects to do so), if
the flight is operated as a non-revenue flight.
(l) Alternative Methods of Compliance
(AMOCs)
(1) The Manager, Seattle Aircraft
Certification Office (ACO), FAA, has the
authority to approve AMOCs for this AD, if
requested using the procedures found in 14
CFR 39.19. In accordance with 14 CFR 39.19,
send your request to your principal inspector
or local Flight Standards District Office, as
appropriate. If sending information directly
to the manager of the ACO, send it to the
attention of the person identified in the
Related Information section of this AD.
Information may be emailed to: 9-ANMSeattle-ACO-AMOC-Requests@faa.gov.
(2) Before using any approved AMOC,
notify your appropriate principal inspector,
or lacking a principal inspector, the manager
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of the local flight standards district office/
certificate holding district office.
(3) An AMOC that provides an acceptable
level of safety may be used for any repair
required by this AD if it is approved by the
Boeing Commercial Airplanes Organization
Designation Authorization (ODA) that has
been authorized by the Manager, Seattle
ACO, to make those findings. For a repair
method to be approved, the repair must meet
the certification basis of the airplane and the
approval must specifically refer to this AD.
(m) Related Information
For more information about this AD,
contact Melanie Violette, Aerospace
Engineer, Airframe Branch, ANM–120S,
FAA, Seattle Aircraft Certification Office
(ACO), 1601 Lind Avenue SW., Renton, WA
98057–3356; phone: 425–917–6422; fax: 425–
917–6590; email: Melanie.violette@faa.gov.
(n) Material Incorporated by Reference
(1) The Director of the Federal Register
approved the incorporation by reference
(IBR) of the service information listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR
part 51.
(2) You must use the following service
information to do the actions required by this
AD, unless the AD specifies otherwise.
(i) Boeing Alert Service Bulletin 777–
32A0082, dated December 9, 2010.
(ii) Boeing Service Bulletin 777–32–0085,
dated April 14, 2011.
(iii) Boeing Special Attention Service
Bulletin 777–32–0080, dated July 10, 2008.
(iv) Boeing Special Attention Service
Bulletin 777–32–0080, Revision 1, dated
April 16, 2009.
(3) For service information identified in
this AD, contact Boeing Commercial
Airplanes, Attention: Data & Services
Management, P. O. Box 3707, MC 2H–65,
Seattle, WA 98124–2207; phone: 206–544–
5000, extension 1; fax: 206–766–5680;
Internet https://www.myboeingfleet.com.
(4) You may review copies of the
referenced service information at the FAA,
Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, WA. For information
on the availability of this material at the
FAA, call 425–227–1221.
(5) You may also review copies of the
service information that is incorporated by
reference at the National Archives and
Records Administration (NARA). For
information on the availability of this
material at NARA, call 202–741–6030, or go
to https://www.archives.gov/federal-register/
cfr/ibr-locations.html.
Issued in Renton, Washington, on
September 19, 2012.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 2012–23790 Filed 10–2–12; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2012–0060; Directorate
Identifier 2012–NE–02–AD; Amendment 39–
17123; AD 2012–14–09]
RIN 2120–AA64
Airworthiness Directives; Pratt &
Whitney (P&W) Division Turbofan
Engines
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
We are adopting a new
airworthiness directive (AD) for certain
P&W PW4000 series turbofan engines.
This AD was prompted by reports of 3rd
and 4th stage vane fractures in the lowpressure turbine (LPT) of certain
PW4000–94’’ and PW4000–100’’
turbofan engines. This AD requires
dimensional inspections of LPT 3rd
stage vanes and the rear turbine case,
inspection of LPT 4th stage vanes at the
next LPT overhaul and removal of vanes
with non-conforming airfoil fillet radii
and vanes with more than one strip and
recoat repair. This AD also requires
disassembly and reassembly of the 2nd
stage high-pressure turbine (HPT) rotor
and 3rd stage LPT rotor at the next HPT
and LPT overhauls. We are issuing this
AD to prevent 3rd and 4th stage vane
fractures in the LPT, damage to the LPT
rotor, uncontained engine failure, and
damage to the airplane.
DATES: This AD is effective November 7,
2012.
ADDRESSES: For more information about
this AD, contact James Gray, Aerospace
Engineer, Engine Certification Office,
FAA, Engine & Propeller Directorate, 12
New England Executive Park,
Burlington, MA; phone: 781–238–7742;
fax: 781–238–7199; email:
james.e.gray@faa.gov.
SUMMARY:
Examining the AD Docket
You may examine the AD docket on
the Internet at https://
www.regulations.gov; or in person at the
Docket Management Facility between 9
a.m. and 5 p.m., Monday through
Friday, except Federal holidays. The AD
docket contains this AD, the regulatory
evaluation, any comments received, and
other information. The address for the
Docket Office (phone: 800–647–5527) is
Document Management Facility, U.S.
Department of Transportation, Docket
Operations, M–30, West Building
Ground Floor, Room W12–140, 1200
New Jersey Avenue SE., Washington,
DC 20590.
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FOR FURTHER INFORMATION CONTACT:
James Gray, Aerospace Engineer, Engine
Certification Office, FAA, Engine &
Propeller Directorate, 12 New England
Executive Park, Burlington, MA; phone:
781–238–7742; fax: 781–238–7199;
email: james.e.gray@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion
We issued a notice of proposed
rulemaking (NPRM) to amend 14 CFR
part 39 to include an AD that would
apply to the specified products. That
NPRM published in the Federal
Register on March 2, 2012 (77 FR
12755). That NPRM proposed to require
dimensional inspections of 3rd stage
vanes and the rear turbine case. That
NPRM also proposed to require
inspection of 4th stage vanes at the next
LPT overhaul and removal of vanes with
non-conforming airfoil fillet radii and
vanes with more than one strip and
recoat repair. That NPRM also proposed
to require disassembly and reassembly
of the 2nd stage HPT rotor and 3rd stage
LPT rotor at the next HPT and LPT
overhauls.
Comments
We gave the public the opportunity to
participate in developing this AD. The
following presents the comments
received on the proposal and the FAA’s
response to each comment.
Agreement With the Proposed AD
Two commenters, Boeing and FedEx,
agreed with the intent of the proposed
AD.
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Request To Change Compliance Time
for the 4th Stage Vanes
One commenter, China Cargo
Airlines, requested that we change the
inspection compliance time for the LPT
4th stage vanes from ‘‘next LPT
overhaul’’ to ‘‘next engine overhaul.’’
The commenter stated that LPT
overhauls are typically performed every
other shop visit, which could be in sixto-eight years. The commenter thought
that the risk of having a 4th stage vane
failure during that time was too high.
We do not agree. We determined that
performing the inspections at the next
LPT overhaul after the effective date of
the AD provides an acceptable level of
safety, and that we do not need to
reduce the interval. We did not change
the AD.
Request for Credit for Prior Compliance
FedEx requested that a statement be
included authorizing credit for prior
compliance as they have already been
performing the requirements of the
proposed AD.
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We do not agree. Paragraph (e) of the
proposed AD already allows credit for
prior compliance. That paragraph states
to comply with the AD within the
compliance times specified, unless
already done. We did not change the
AD.
Request To Reference Pratt & Whitney
Special Instruction No. 17F–09
One commenter, Martinair Holland,
requested that we add a reference to
Pratt & Whitney Special Instruction No.
17F–09 as an alternate method of
compliance (AMOC) for paragraph
(e)(1)(iii). The commenter stated that
they have been checking the 3rd stage
vanes for adequate engagement using
that Special Instruction.
We do not agree. The AD requires
dimensional inspections that are not
included in Special Instruction No.
17F–09. Also, we do not include
AMOCs in the requirements of an AD.
You may, however, seek an AMOC
using the procedures specified in the
AD. We did not add that Special
Instruction reference to the AD.
Request To Add Service Bulletins as
Alternate Methods of Compliance
Martinair Holland, United Airlines,
and Onur Air, requested that we add
references to Pratt & Whitney Service
Bulletins (SBs) PW4ENG 72–798,
PW4ENG 72–804, and PW4G–100–72–
221, as alternate methods of compliance
to paragraph (e)(1)(v). The commenters
stated that they have been inspecting
the LPT 4th stage vanes using these SBs.
We do not agree. Paragraph (e) of the
proposed AD states to comply with the
AD within the compliance times
specified, unless already done. If you
have already done the proposed actions,
then no further action is required to
comply with paragraph (e)(1)(v). Also,
as noted above, we do not include
AMOCs in the requirements of an AD.
We did not change the AD.
Request To Include the Part Numbers
(P/Ns) of the LPT 4th Stage Vanes
Pratt & Whitney requested that we
include the P/Ns of the LPT 4th stage
vanes that are subject to the one-time
strip and recoat requirement. The
commenter stated that it is possible that
future designs of LPT 4th stage vanes
would not be restricted to a single strip
and recoat requirement.
We agree. We listed the P/Ns of the
affected LPT 4th stage vanes in the AD.
Request To Define the Word
‘‘Guidance’’
United Airlines requested that we
define the word ‘‘guidance’’ which we
used in paragraph (g) of the proposed
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60289
AD, or, that we revise the wording to
specifically detail the inspection/build
procedure to be used. The commenter
states that using the term ‘‘guidance’’
does not denote a specific requirement
and only suggests a general direction to
be followed.
We agree. Use of the word ‘‘guidance’’
in this AD may have caused confusion.
We deleted the ‘‘guidance’’ paragraphs
listed under Related Information from
the AD.
Request To Update Guidance Service
Information
Pratt & Whitney and United Parcel
Service Co. (UPS) requested that we add
the words ‘‘or later’’ after the service
information date references in
paragraph (g) of the proposed AD. They
also requested that we clarify that the
referenced service information could be
updated, and compliance to that
updated service information would be
acceptable. One of the commenters was
concerned that service information
listed as guidance would be controlled
in the same way as service information
that is incorporated by reference in the
AD.
We do not agree. We do not know
how documents will be revised in the
future. This AD, however, was revised
to remove references to related service
information, and therefore the comment
no longer applies. We did not change
the AD.
Request To Remove the Term
‘‘Overhaul’’
United Airlines and UPS requested
that we remove the term ‘‘overhaul,’’
such as ‘‘LPT overhaul’’ and ‘‘HPT
overhaul’’ from the proposed AD
compliance, as the term ‘‘overhaul’’ is
not industry standard and therefore
subjective. The commenters suggested a
few alternatives to use instead of the
term ‘‘overhaul.’’
We partially agree. We do not agree
that the term ‘‘overhaul’’ should be
removed, but we do agree that it should
be defined. We added a definition
paragraph which states that, for the
purpose of this AD, an overhaul is when
all disks in the rotor are removed from
the engine and the blades are removed.
Request To Clarify Approved Methods
of Compliance
UPS requested that we clarify that the
service information listed under Related
Information are approved methods of
compliance to the proposed AD. They
further stated that, as-written, it is not
clear that they are approved methods of
compliance.
We agree that the AD should be
clarified. We revised the AD by
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removing references to related service
information.
on an average dimension. We did not
change the AD.
Request To Duplicate the Strip and
Recoat Requirements
United Airlines requested that we
duplicate the strip and recoat
requirements and make them part of
Inspection/Check-01 or Inspection/
Check-03 of the PW4000 Engine
Cleaning Inspection and Repair (CIR)
Manual. The commenter stated that the
strip and recoat limits are currently
located in repair-14 of the PW4000 CIR
Manual, but repair-14 is not always
required to return a vane cluster to
service. The commenter stated that the
strip and recoat requirements need to be
part of the normal inspection process.
We do not agree. The AD mandates
that the inspection be performed once,
at the next LPT overhaul. That
inspection will purge the fleet of LPT
4th stage vanes that have had more than
one strip and recoat repair. After that
inspection, LPT 4th stage vanes are not
allowed to have more than one strip and
recoat repair, as specified in the
installation prohibition paragraph (f).
Revising the engine manuals to relocate
the inspection requirements is
unnecessary. We did not change the AD.
Request To Change ‘‘Ensure Adequate
Engagement’’
United Airlines requested that in
proposed AD paragraphs (e)(1)(iii) and
(e)(1)(iv), we change ‘‘ensure adequate
engagement’’ to ‘‘dimensionally inspect
the applicable LPT case slot serviceable
dimensions and 3rd stage vane
serviceable dimensions per the
appropriate CIR.’’ The commenter also
requested that we list the specific
dimensions to inspect by index number.
The commenter stated that no mechanic
can deduce what an adequate
engagement is because it is not specific
enough.
We agree. We changed paragraph
(e)(1)(iii) to ‘‘dimensionally examine
index 13 through index 34 of the LPT
3rd stage vane cluster assembly.’’ We
also changed paragraph (e)(1)(iv) to
‘‘dimensionally examine index 23 and
index 24 of the vane engagement slots
on the rear turbine case, where the 3rd
stage vane is installed.’’ We also listed
the specific dimensions to inspect by
index number, and included the
supporting figures in this AD.
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Request To Remove Reference to 4th
Stage Vanes With an Unknown Number
of Strip and Recoat Repairs
United Airlines stated that there is no
way to identify vanes with an unknown
number of strip and recoat repairs. The
commenter stated that if there were no
markings on the vane, it would indicate
that no strip and recoat repairs were
performed. This could lead to scrapping
vanes that could otherwise be repaired
and returned to service.
We agree. We changed the AD to
eliminate the reference to LPT 4th stage
vanes with an unknown number of strip
and recoat repairs.
Request To Make the CIR Inspections
More Specific
United Airlines requested that in
proposed AD paragraph (e)(1)(iv) we
make the CIR inspections more specific
for the LPT case dimensions. The
commenter stated that there are
different ways to perform the
measurements and it is not clear
whether the dimension to measure is
based on an average or an individual
diametric dimension.
We do not agree. A specific
measurement technique is not defined
because multiple measurement
techniques exist that are acceptable. The
only diametric dimensional inspection
required by the AD is index 24, which
would be acceptable to measure based
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Request To Eliminate Paragraphs
United Airlines requested that we
eliminate paragraphs (e)(1)(ii) through
(e)(1)(iv) and (e)(2). The commenter
stated that these paragraphs are related
to procedures that are in the engine
manual that operators are already
performing. If they are left in the AD,
they will add a significant burden in the
amount of time and paperwork required
to manage and verify compliance to the
AD.
We do not agree. The actions in the
paragraphs the commenter wants
eliminated from the AD represent
changes to the manuals that were
specifically incorporated to address 3rd
and 4th stage vane failures. Although air
carriers operating under 14 Code of
Federal Regulations (CFR) Part 121 are
likely using the most current versions of
the engine manuals, not all operators,
for example, part 91 operators, may be
required to incorporate the latest
versions of the engine manuals.
Therefore, we must maintain these
requirements in the AD to ensure that
all operators comply to resolve the
unsafe condition. We did not change the
AD.
Revision to Cost of Compliance
In reviewing the cost of compliance
estimate made in the NPRM (77 FR
12755, March 2, 2012), we determined
that we were unable to substantiate our
prorated cost estimate for limiting the
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number of strip and recoat repairs since
we do not know how many vanes are
operating with more than one strip and
recoat repair. We, therefore, removed
the estimate of the useful part life
expectancy and only included the
replacement parts cost. The total cost
estimate changed from $32,147,170 to
$9,214,170.
Conclusion
We reviewed the relevant data,
considered the comments received, and
determined that air safety and the
public interest require adopting the AD
with the changes described previously.
We have determined that these changes:
• Are consistent with the intent that
was proposed in the NPRM (77 FR
12755, March 2, 2012) for correcting the
unsafe condition; and
• Do not add any additional burden
upon the public than was already
proposed in the NPRM (77 FR 12755,
March 2, 2012).
We also determined that these
changes will not increase the economic
burden on any operator or increase the
scope of the AD.
Costs of Compliance
We estimate that this AD affects 807
engines installed on airplanes of U.S.
registry. We estimate that it will take 2
work-hours per engine to perform the
LPT 3rd stage vane cluster assembly and
rear turbine case inspections. The
average labor rate is $85 per work-hour.
We expect that about 1,870 LPT 4th
stage vane cluster assemblies will be
found with the non-conforming casting
identification. Replacement parts cost
about $4,854. Based on these figures, we
estimate the cost of the AD on U.S.
operators to be $9,214,170.
Authority for This Rulemaking
Title 49 of the United States Code
specifies the FAA’s authority to issue
rules on aviation safety. Subtitle I,
section 106, describes the authority of
the FAA Administrator. Subtitle VII:
Aviation Programs, describes in more
detail the scope of the Agency’s
authority.
We are issuing this rulemaking under
the authority described in Subtitle VII,
Part A, Subpart III, Section 44701:
‘‘General requirements.’’ Under that
section, Congress charges the FAA with
promoting safe flight of civil aircraft in
air commerce by prescribing regulations
for practices, methods, and procedures
the Administrator finds necessary for
safety in air commerce. This regulation
is within the scope of that authority
because it addresses an unsafe condition
that is likely to exist or develop on
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products identified in this rulemaking
action.
Regulatory Findings
This AD will not have federalism
implications under Executive Order
13132. This AD will not have a
substantial direct effect 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.
For the reasons discussed above, I
certify that this AD:
(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),
(3) Will not affect intrastate aviation
in Alaska, and
(4) 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation
safety, Incorporation by reference,
Safety.
Adoption of the Amendment
Accordingly, under the authority
delegated to me by the Administrator,
the FAA amends 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.
§ 39.13
[Amended]
2. The FAA amends § 39.13 by adding
the following new airworthiness
directive (AD):
■
2012–14–09 Pratt & Whitney Division:
Amendment 39–17123; Docket No.
FAA–2012–0060; Directorate Identifier
2012–NE–02–AD.
(a) Effective Date
This AD is effective November 7, 2012.
(b) Affected ADs
None.
(c) Applicability
This AD applies to the following Pratt &
Whitney Division turbofan engines:
60291
(1) PW4000–94″ engine models PW4050,
PW4052, PW4056, PW4152, PW4156,
PW4650, PW4060, PW4060A, PW4060C,
PW4062, PW4062A, PW4156A, PW4158,
PW4160, PW4460, and PW4462 including
models with any dash number suffix.
(2) PW4000–100″ engine models PW4164,
PW4164C, PW4164C/B, PW4168, PW4168A,
PW4164–1D, PW4164C–1D, PW4164C/B–1D,
PW4168–1D, PW4168A–1D, and PW4170.
(d) Unsafe Condition
This AD was prompted by reports of 3rd
and 4th stage vane fractures in the lowpressure turbine (LPT) of certain PW4000–
94″ and PW4000–100″ turbofan engines.
These fractures caused an uncontained
engine failure and an LPT case puncture, and
resulted in multiple in flight shutdowns. We
are issuing this AD to prevent 3rd and 4th
stage vane fractures in the LPT, damage to
the LPT rotor, uncontained engine failure,
and damage to the airplane.
(e) Compliance
Comply with this AD within the
compliance times specified, unless already
done.
(1) At the next LPT overhaul, do the
following:
(i) Remove LPT 4th stage vanes that have
a P/N listed in Table 1 to paragraph (e) of this
AD from service if more than one strip and
recoat repair has been performed.
TABLE 1 TO PARAGRAPH (e)—AFFECTED LPT 4TH STAGE VANE P/NS
50N174
50N474–01
50N474–001
50N574–01
50N674–01
50N774–01
50N774–001
51N174–01
(ii) Re-assemble the 3rd stage LPT rotor
blades by alternating heavy blades next to
light blades and balancing blades of similar
weights 180 degrees across the rotor.
51N174–001
51N174–002
51N174–003
51N374–01
51N374–001
51N674–01
52N274–01
52N474–01
(iii) Dimensionally examine index 13
through index 34 of the LPT 3rd stage vane
cluster assembly. Use Table 2 to paragraph
(e) of this AD and Figure 1, Figure 2, and
52N574–01
52N674–01
51N774–01
52N774–01
Figure 3 to paragraph (e) of this AD to
determine whether the vane is eligible for
installation.
TABLE 2 TO PARAGRAPH (e)—DETERMINATION OF VANE ELIGIBILITY
Inspect:
Eligible for installation limits:
13
14
15
16
17
18
19
20
21
22
1.820–1.830 inches (46.23–46.48 mm).
1.920–1.930 inches (48.77–49.02 mm).
3.200 inches (81.280 mm) Basic.
0.900 inch (22.860 mm) Basic.
0.365 inch (9.271 mm) Basic.
0.350 inch (8.890 mm) Basic.
0.160 inch (4.064 mm) Basic.
0.772 inch (19.609 mm) Basic.
72° Basic.
22.382 inch (568.503 mm) Radius—Origin on Plane S Basic.
21.052 inch (534.721 mm) Radius—Origin on Plane S, concentric with Index 8
Basic.
Angle from Plane S to Plane SL 3°4′37″
Basic.
Angle from Plane S to Plane SM 6°9′14″
Basic.
90° Basic for typical airfoil section.
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27:
Distance from rear foot outer diameter surface to airfoil section along Planes S, SL, and SM.
For Section B–B: .......................................................................................................................
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TABLE 2 TO PARAGRAPH (E)—DETERMINATION OF VANE ELIGIBILITY—Continued
Inspect:
Eligible for installation limits:
For Section E–E: .......................................................................................................................
For Section J–J: .........................................................................................................................
3.181 inches (80.797 mm).
1.935 inches (49.149 mm).
28:
Airfoil chord at Section J–J (1.935 inches (49.149 mm) from rear foot outer diameter surface at
Planes S, SL, and SM).
At Section E–E (3.181 inches (80.797 mm) from rear foot outer diameter surface at Planes S,
SL, and SM).
At Section B–B (5.241 inches (133.121 mm) from rear foot outer diameter surface at Planes S,
SL, and SM).
1.346 inches (34.188 mm) minimum.
Airfoil thickness at Section J–J (1.935 inches (49.149 mm) from rear foot outer diameter surface
at Planes S, SL, and SM).
At Section E–E (3.181 inches (80.797 mm) from rear foot outer diameter surface at Planes S,
SL, and SM).
At Section B–B (5.241 inches (133.121 mm) from rear foot outer diameter surface at Planes S,
SL, and SM).
0.239 inch (6.071 mm) minimum.
Distance to trailing edge measurement ............................................................................................
0.062 inch (1.575 mm).
Airfoil trailing edge thickness ............................................................................................................
0.030 inch (0.762 mm) minimum.
Dimension .........................................................................................................................................
0.315–0.324 inch (8.001–8.230 mm) diameter.
Dimension .........................................................................................................................................
6.785–6.795 inches (172.34–172.59 mm).
Dimension .........................................................................................................................................
0.692–0.714 inch (17.58–18.14 mm).
1.314 inches (33.376 mm) minimum.
1.188 inches (30.175 mm) minimum.
29:
0.183 inch (4.648 mm) minimum.
0.139 inch (3.531 mm) minimum.
30:
31:
32:
33:
34:
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60294
Federal Register / Vol. 77, No. 192 / Wednesday, October 3, 2012 / Rules and Regulations
BILLING CODE 4910–13–C
(iv) Dimensionally examine index 23 and
index 24 of the vane engagement slots on the
rear turbine case, where the 3rd stage vane
is installed. Use Table 3 to paragraph (e) of
this AD and Figure 4 to paragraph (e) of this
AD to determine whether the case is eligible
for installation.
60295
TABLE 3 TO PARAGRAPH (e)—DETERMINATION OF CASE ELIGIBILITY—
Continued
Inspect:
Eligible for installation limits:
24 .........
0.097 inch (2.464 mm) minimum.
TABLE 3 TO PARAGRAPH (e)—
DETERMINATION OF CASE ELIGIBILITY
1.875 inch (47.625 mm) minimum.
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Eligible for installation limits:
23 .........
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Inspect:
Federal Register / Vol. 77, No. 192 / Wednesday, October 3, 2012 / Rules and Regulations
(v) Inspect the 44 LPT 4th stage vane
cluster assemblies P/N 52N774–01 for casting
identification ‘‘51N554AT 1447 2S1C1’’ and
P/N 52N674–01 for casting identification
‘‘51N454AT 655 2S1C1.’’ Remove the vane
cluster assembly from service if either of
these casting identifications is found.
(2) At the next high-pressure turbine (HPT)
overhaul, re-assemble the 2nd stage HPT
rotor blades by alternating heavy blades next
to light blades and balancing blades of
similar weights 180 degrees across the rotor.
(i) Related Information
(f) Installation Prohibition
Issued in Burlington, Massachusetts, on
September 20, 2012.
Diane M. Cook,
Acting Manager, Engine & Propeller
Directorate, Aircraft Certification Service.
After the effective date of this AD, do not
install or reinstall into any engine any LPT
4th stage vanes with a P/N listed in Table 1
to paragraph (e) of this AD that are at piecepart exposure and have had more than one
strip and recoat repair.
DEPARTMENT OF TRANSPORTATION
For more information about this AD,
contact James Gray, Aerospace Engineer,
Engine Certification Office, FAA, Engine &
Propeller Directorate, 12 New England
Executive Park, Burlington, MA; phone: 781–
238–7742; fax: 781–238–7199; email:
james.e.gray@faa.gov.
(j) Material Incorporated by Reference
[FR Doc. 2012–23791 Filed 10–2–12; 8:45 am]
BILLING CODE 4910–13–P
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(1) For the purpose of this AD, an HPT or
LPT overhaul occurs when all disks in the
rotor are removed from the engine and the
blades are removed.
(2) For the purpose of this AD, piece-part
exposure means that the part is removed
from the engine and completely
disassembled.
(h) Alternative Methods of Compliance
(AMOCs)
The Manager, Engine Certification Office,
FAA, may approve AMOCs for this AD. Use
the procedures found in 14 CFR 39.19 to
make your request.
14:51 Oct 02, 2012
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14 CFR Part 39
[Docket No. FAA–2011–1411; Directorate
Identifier 2011–NM–074–AD; Amendment
39–17206; AD 2012–19–11]
RIN 2120–AA64
None.
(g) Definitions
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Airworthiness Directives; The Boeing
Company Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
We are adopting a new
airworthiness directive (AD) for certain
The Boeing Company Model 737
airplanes. This AD was prompted by a
report of a flightcrew not receiving an
aural warning during a lack of cabin
pressurization event. This AD requires
incorporating design changes to
improve the reliability of the cabin
altitude warning system by installing a
redundant cabin altitude pressure
switch, replacing the aural warning
module (AWM) with a new or reworked
AWM, and changing certain wire
bundles or connecting certain
previously capped and stowed wires as
SUMMARY:
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60296
]]>Agencies
[Federal Register Volume 77, Number 192 (Wednesday, October 3, 2012)]
[Rules and Regulations]
[Pages 60288-60296]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-23791]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2012-0060; Directorate Identifier 2012-NE-02-AD;
Amendment 39-17123; AD 2012-14-09]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney (P&W) Division Turbofan
Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We are adopting a new airworthiness directive (AD) for certain
P&W PW4000 series turbofan engines. This AD was prompted by reports of
3rd and 4th stage vane fractures in the low-pressure turbine (LPT) of
certain PW4000-94'' and PW4000-100'' turbofan engines. This AD requires
dimensional inspections of LPT 3rd stage vanes and the rear turbine
case, inspection of LPT 4th stage vanes at the next LPT overhaul and
removal of vanes with non-conforming airfoil fillet radii and vanes
with more than one strip and recoat repair. This AD also requires
disassembly and reassembly of the 2nd stage high-pressure turbine (HPT)
rotor and 3rd stage LPT rotor at the next HPT and LPT overhauls. We are
issuing this AD to prevent 3rd and 4th stage vane fractures in the LPT,
damage to the LPT rotor, uncontained engine failure, and damage to the
airplane.
DATES: This AD is effective November 7, 2012.
ADDRESSES: For more information about this AD, contact James Gray,
Aerospace Engineer, Engine Certification Office, FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington, MA;
phone: 781-238-7742; fax: 781-238-7199; email: james.e.gray@faa.gov.
Examining the AD Docket
You may examine the AD docket on the Internet at https://www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, the regulatory evaluation,
any comments received, and other information. The address for the
Docket Office (phone: 800-647-5527) is Document Management Facility,
U.S. Department of Transportation, Docket Operations, M-30, West
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.
[[Page 60289]]
FOR FURTHER INFORMATION CONTACT: James Gray, Aerospace Engineer, Engine
Certification Office, FAA, Engine & Propeller Directorate, 12 New
England Executive Park, Burlington, MA; phone: 781-238-7742; fax: 781-
238-7199; email: james.e.gray@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 to include an AD that would apply to the specified products.
That NPRM published in the Federal Register on March 2, 2012 (77 FR
12755). That NPRM proposed to require dimensional inspections of 3rd
stage vanes and the rear turbine case. That NPRM also proposed to
require inspection of 4th stage vanes at the next LPT overhaul and
removal of vanes with non-conforming airfoil fillet radii and vanes
with more than one strip and recoat repair. That NPRM also proposed to
require disassembly and reassembly of the 2nd stage HPT rotor and 3rd
stage LPT rotor at the next HPT and LPT overhauls.
Comments
We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the proposal
and the FAA's response to each comment.
Agreement With the Proposed AD
Two commenters, Boeing and FedEx, agreed with the intent of the
proposed AD.
Request To Change Compliance Time for the 4th Stage Vanes
One commenter, China Cargo Airlines, requested that we change the
inspection compliance time for the LPT 4th stage vanes from ``next LPT
overhaul'' to ``next engine overhaul.'' The commenter stated that LPT
overhauls are typically performed every other shop visit, which could
be in six-to-eight years. The commenter thought that the risk of having
a 4th stage vane failure during that time was too high.
We do not agree. We determined that performing the inspections at
the next LPT overhaul after the effective date of the AD provides an
acceptable level of safety, and that we do not need to reduce the
interval. We did not change the AD.
Request for Credit for Prior Compliance
FedEx requested that a statement be included authorizing credit for
prior compliance as they have already been performing the requirements
of the proposed AD.
We do not agree. Paragraph (e) of the proposed AD already allows
credit for prior compliance. That paragraph states to comply with the
AD within the compliance times specified, unless already done. We did
not change the AD.
Request To Reference Pratt & Whitney Special Instruction No. 17F-09
One commenter, Martinair Holland, requested that we add a reference
to Pratt & Whitney Special Instruction No. 17F-09 as an alternate
method of compliance (AMOC) for paragraph (e)(1)(iii). The commenter
stated that they have been checking the 3rd stage vanes for adequate
engagement using that Special Instruction.
We do not agree. The AD requires dimensional inspections that are
not included in Special Instruction No. 17F-09. Also, we do not include
AMOCs in the requirements of an AD. You may, however, seek an AMOC
using the procedures specified in the AD. We did not add that Special
Instruction reference to the AD.
Request To Add Service Bulletins as Alternate Methods of Compliance
Martinair Holland, United Airlines, and Onur Air, requested that we
add references to Pratt & Whitney Service Bulletins (SBs) PW4ENG 72-
798, PW4ENG 72-804, and PW4G-100-72-221, as alternate methods of
compliance to paragraph (e)(1)(v). The commenters stated that they have
been inspecting the LPT 4th stage vanes using these SBs.
We do not agree. Paragraph (e) of the proposed AD states to comply
with the AD within the compliance times specified, unless already done.
If you have already done the proposed actions, then no further action
is required to comply with paragraph (e)(1)(v). Also, as noted above,
we do not include AMOCs in the requirements of an AD. We did not change
the AD.
Request To Include the Part Numbers (P/Ns) of the LPT 4th Stage Vanes
Pratt & Whitney requested that we include the P/Ns of the LPT 4th
stage vanes that are subject to the one-time strip and recoat
requirement. The commenter stated that it is possible that future
designs of LPT 4th stage vanes would not be restricted to a single
strip and recoat requirement.
We agree. We listed the P/Ns of the affected LPT 4th stage vanes in
the AD.
Request To Define the Word ``Guidance''
United Airlines requested that we define the word ``guidance''
which we used in paragraph (g) of the proposed AD, or, that we revise
the wording to specifically detail the inspection/build procedure to be
used. The commenter states that using the term ``guidance'' does not
denote a specific requirement and only suggests a general direction to
be followed.
We agree. Use of the word ``guidance'' in this AD may have caused
confusion. We deleted the ``guidance'' paragraphs listed under Related
Information from the AD.
Request To Update Guidance Service Information
Pratt & Whitney and United Parcel Service Co. (UPS) requested that
we add the words ``or later'' after the service information date
references in paragraph (g) of the proposed AD. They also requested
that we clarify that the referenced service information could be
updated, and compliance to that updated service information would be
acceptable. One of the commenters was concerned that service
information listed as guidance would be controlled in the same way as
service information that is incorporated by reference in the AD.
We do not agree. We do not know how documents will be revised in
the future. This AD, however, was revised to remove references to
related service information, and therefore the comment no longer
applies. We did not change the AD.
Request To Remove the Term ``Overhaul''
United Airlines and UPS requested that we remove the term
``overhaul,'' such as ``LPT overhaul'' and ``HPT overhaul'' from the
proposed AD compliance, as the term ``overhaul'' is not industry
standard and therefore subjective. The commenters suggested a few
alternatives to use instead of the term ``overhaul.''
We partially agree. We do not agree that the term ``overhaul''
should be removed, but we do agree that it should be defined. We added
a definition paragraph which states that, for the purpose of this AD,
an overhaul is when all disks in the rotor are removed from the engine
and the blades are removed.
Request To Clarify Approved Methods of Compliance
UPS requested that we clarify that the service information listed
under Related Information are approved methods of compliance to the
proposed AD. They further stated that, as-written, it is not clear that
they are approved methods of compliance.
We agree that the AD should be clarified. We revised the AD by
[[Page 60290]]
removing references to related service information.
Request To Duplicate the Strip and Recoat Requirements
United Airlines requested that we duplicate the strip and recoat
requirements and make them part of Inspection/Check-01 or Inspection/
Check-03 of the PW4000 Engine Cleaning Inspection and Repair (CIR)
Manual. The commenter stated that the strip and recoat limits are
currently located in repair-14 of the PW4000 CIR Manual, but repair-14
is not always required to return a vane cluster to service. The
commenter stated that the strip and recoat requirements need to be part
of the normal inspection process.
We do not agree. The AD mandates that the inspection be performed
once, at the next LPT overhaul. That inspection will purge the fleet of
LPT 4th stage vanes that have had more than one strip and recoat
repair. After that inspection, LPT 4th stage vanes are not allowed to
have more than one strip and recoat repair, as specified in the
installation prohibition paragraph (f). Revising the engine manuals to
relocate the inspection requirements is unnecessary. We did not change
the AD.
Request To Remove Reference to 4th Stage Vanes With an Unknown Number
of Strip and Recoat Repairs
United Airlines stated that there is no way to identify vanes with
an unknown number of strip and recoat repairs. The commenter stated
that if there were no markings on the vane, it would indicate that no
strip and recoat repairs were performed. This could lead to scrapping
vanes that could otherwise be repaired and returned to service.
We agree. We changed the AD to eliminate the reference to LPT 4th
stage vanes with an unknown number of strip and recoat repairs.
Request To Make the CIR Inspections More Specific
United Airlines requested that in proposed AD paragraph (e)(1)(iv)
we make the CIR inspections more specific for the LPT case dimensions.
The commenter stated that there are different ways to perform the
measurements and it is not clear whether the dimension to measure is
based on an average or an individual diametric dimension.
We do not agree. A specific measurement technique is not defined
because multiple measurement techniques exist that are acceptable. The
only diametric dimensional inspection required by the AD is index 24,
which would be acceptable to measure based on an average dimension. We
did not change the AD.
Request To Change ``Ensure Adequate Engagement''
United Airlines requested that in proposed AD paragraphs
(e)(1)(iii) and (e)(1)(iv), we change ``ensure adequate engagement'' to
``dimensionally inspect the applicable LPT case slot serviceable
dimensions and 3rd stage vane serviceable dimensions per the
appropriate CIR.'' The commenter also requested that we list the
specific dimensions to inspect by index number. The commenter stated
that no mechanic can deduce what an adequate engagement is because it
is not specific enough.
We agree. We changed paragraph (e)(1)(iii) to ``dimensionally
examine index 13 through index 34 of the LPT 3rd stage vane cluster
assembly.'' We also changed paragraph (e)(1)(iv) to ``dimensionally
examine index 23 and index 24 of the vane engagement slots on the rear
turbine case, where the 3rd stage vane is installed.'' We also listed
the specific dimensions to inspect by index number, and included the
supporting figures in this AD.
Request To Eliminate Paragraphs
United Airlines requested that we eliminate paragraphs (e)(1)(ii)
through (e)(1)(iv) and (e)(2). The commenter stated that these
paragraphs are related to procedures that are in the engine manual that
operators are already performing. If they are left in the AD, they will
add a significant burden in the amount of time and paperwork required
to manage and verify compliance to the AD.
We do not agree. The actions in the paragraphs the commenter wants
eliminated from the AD represent changes to the manuals that were
specifically incorporated to address 3rd and 4th stage vane failures.
Although air carriers operating under 14 Code of Federal Regulations
(CFR) Part 121 are likely using the most current versions of the engine
manuals, not all operators, for example, part 91 operators, may be
required to incorporate the latest versions of the engine manuals.
Therefore, we must maintain these requirements in the AD to ensure that
all operators comply to resolve the unsafe condition. We did not change
the AD.
Revision to Cost of Compliance
In reviewing the cost of compliance estimate made in the NPRM (77
FR 12755, March 2, 2012), we determined that we were unable to
substantiate our prorated cost estimate for limiting the number of
strip and recoat repairs since we do not know how many vanes are
operating with more than one strip and recoat repair. We, therefore,
removed the estimate of the useful part life expectancy and only
included the replacement parts cost. The total cost estimate changed
from $32,147,170 to $9,214,170.
Conclusion
We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
the AD with the changes described previously. We have determined that
these changes:
Are consistent with the intent that was proposed in the
NPRM (77 FR 12755, March 2, 2012) for correcting the unsafe condition;
and
Do not add any additional burden upon the public than was
already proposed in the NPRM (77 FR 12755, March 2, 2012).
We also determined that these changes will not increase the
economic burden on any operator or increase the scope of the AD.
Costs of Compliance
We estimate that this AD affects 807 engines installed on airplanes
of U.S. registry. We estimate that it will take 2 work-hours per engine
to perform the LPT 3rd stage vane cluster assembly and rear turbine
case inspections. The average labor rate is $85 per work-hour. We
expect that about 1,870 LPT 4th stage vane cluster assemblies will be
found with the non-conforming casting identification. Replacement parts
cost about $4,854. Based on these figures, we estimate the cost of the
AD on U.S. operators to be $9,214,170.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on
[[Page 60291]]
products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect 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.
For the reasons discussed above, I certify that this AD:
(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),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
0
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]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):
2012-14-09 Pratt & Whitney Division: Amendment 39-17123; Docket No.
FAA-2012-0060; Directorate Identifier 2012-NE-02-AD.
(a) Effective Date
This AD is effective November 7, 2012.
(b) Affected ADs
None.
(c) Applicability
This AD applies to the following Pratt & Whitney Division
turbofan engines:
(1) PW4000-94'' engine models PW4050, PW4052, PW4056, PW4152,
PW4156, PW4650, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4156A,
PW4158, PW4160, PW4460, and PW4462 including models with any dash
number suffix.
(2) PW4000-100'' engine models PW4164, PW4164C, PW4164C/B,
PW4168, PW4168A, PW4164-1D, PW4164C-1D, PW4164C/B-1D, PW4168-1D,
PW4168A-1D, and PW4170.
(d) Unsafe Condition
This AD was prompted by reports of 3rd and 4th stage vane
fractures in the low-pressure turbine (LPT) of certain PW4000-94''
and PW4000-100'' turbofan engines. These fractures caused an
uncontained engine failure and an LPT case puncture, and resulted in
multiple in flight shutdowns. We are issuing this AD to prevent 3rd
and 4th stage vane fractures in the LPT, damage to the LPT rotor,
uncontained engine failure, and damage to the airplane.
(e) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(1) At the next LPT overhaul, do the following:
(i) Remove LPT 4th stage vanes that have a P/N listed in Table 1
to paragraph (e) of this AD from service if more than one strip and
recoat repair has been performed.
Table 1 to Paragraph (e)--Affected LPT 4th Stage Vane P/Ns
------------------------------------------------------------------------
------------------------------------------------------------------------
50N174 50N674-01 51N174-001 51N374-001 52N574-01
50N474-01 50N774-01 51N174-002 51N674-01 52N674-01
50N474-001 50N774-001 51N174-003 52N274-01 51N774-01
50N574-01 51N174-01 51N374-01 52N474-01 52N774-01
------------------------------------------------------------------------
(ii) Re-assemble the 3rd stage LPT rotor blades by alternating
heavy blades next to light blades and balancing blades of similar
weights 180 degrees across the rotor.
(iii) Dimensionally examine index 13 through index 34 of the LPT
3rd stage vane cluster assembly. Use Table 2 to paragraph (e) of
this AD and Figure 1, Figure 2, and Figure 3 to paragraph (e) of
this AD to determine whether the vane is eligible for installation.
Table 2 to Paragraph (e)--Determination of Vane Eligibility
----------------------------------------------------------------------------------------------------------------
Inspect: Eligible for installation limits:
----------------------------------------------------------------------------------------------------------------
13.......................................... 1.820-1.830 inches (46.23-46.48 mm).
14.......................................... 1.920-1.930 inches (48.77-49.02 mm).
15.......................................... 3.200 inches (81.280 mm) Basic.
16.......................................... 0.900 inch (22.860 mm) Basic.
17.......................................... 0.365 inch (9.271 mm) Basic.
18.......................................... 0.350 inch (8.890 mm) Basic.
19.......................................... 0.160 inch (4.064 mm) Basic.
20.......................................... 0.772 inch (19.609 mm) Basic.
21.......................................... 72[deg] Basic.
22.......................................... 22.382 inch (568.503 mm) Radius--Origin on Plane S Basic.
23.......................................... 21.052 inch (534.721 mm) Radius--Origin on Plane S, concentric
with Index 8 Basic.
24.......................................... Angle from Plane S to Plane SL 3[deg]4'37'' Basic.
25.......................................... Angle from Plane S to Plane SM 6[deg]9'14'' Basic.
26.......................................... 90[deg] Basic for typical airfoil section.
27:
Distance from rear foot outer diameter
surface to airfoil section along Planes
S, SL, and SM.
For Section B-B:.................... 5.241 inches (133.121 mm).
[[Page 60292]]
For Section E-E:.................... 3.181 inches (80.797 mm).
For Section J-J:.................... 1.935 inches (49.149 mm).
28:
Airfoil chord at Section J-J (1.935 1.346 inches (34.188 mm) minimum.
inches (49.149 mm) from rear foot outer
diameter surface at Planes S, SL, and
SM).
At Section E-E (3.181 inches (80.797 mm) 1.314 inches (33.376 mm) minimum.
from rear foot outer diameter surface
at Planes S, SL, and SM).
At Section B-B (5.241 inches (133.121 1.188 inches (30.175 mm) minimum.
mm) from rear foot outer diameter
surface at Planes S, SL, and SM).
29:
Airfoil thickness at Section J-J (1.935 0.239 inch (6.071 mm) minimum.
inches (49.149 mm) from rear foot outer
diameter surface at Planes S, SL, and
SM).
At Section E-E (3.181 inches (80.797 mm) 0.183 inch (4.648 mm) minimum.
from rear foot outer diameter surface
at Planes S, SL, and SM).
At Section B-B (5.241 inches (133.121 0.139 inch (3.531 mm) minimum.
mm) from rear foot outer diameter
surface at Planes S, SL, and SM).
30:
Distance to trailing edge measurement... 0.062 inch (1.575 mm).
31:
Airfoil trailing edge thickness......... 0.030 inch (0.762 mm) minimum.
32:
Dimension............................... 0.315-0.324 inch (8.001-8.230 mm) diameter.
33:
Dimension............................... 6.785-6.795 inches (172.34-172.59 mm).
34:
Dimension............................... 0.692-0.714 inch (17.58-18.14 mm).
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(iv) Dimensionally examine index 23 and index 24 of the vane
engagement slots on the rear turbine case, where the 3rd stage vane
is installed. Use Table 3 to paragraph (e) of this AD and Figure 4
to paragraph (e) of this AD to determine whether the case is
eligible for installation.
Table 3 to Paragraph (e)--Determination of Case Eligibility
------------------------------------------------------------------------
Inspect: Eligible for installation limits:
------------------------------------------------------------------------
23............................... 1.875 inch (47.625 mm) minimum.
24............................... 0.097 inch (2.464 mm) minimum.
------------------------------------------------------------------------
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(v) Inspect the 44 LPT 4th stage vane cluster assemblies P/N
52N774-01 for casting identification ``51N554AT 1447 2S1C1'' and P/N
52N674-01 for casting identification ``51N454AT 655 2S1C1.'' Remove
the vane cluster assembly from service if either of these casting
identifications is found.
(2) At the next high-pressure turbine (HPT) overhaul, re-
assemble the 2nd stage HPT rotor blades by alternating heavy blades
next to light blades and balancing blades of similar weights 180
degrees across the rotor.
(f) Installation Prohibition
After the effective date of this AD, do not install or reinstall
into any engine any LPT 4th stage vanes with a P/N listed in Table 1
to paragraph (e) of this AD that are at piece-part exposure and have
had more than one strip and recoat repair.
(g) Definitions
(1) For the purpose of this AD, an HPT or LPT overhaul occurs
when all disks in the rotor are removed from the engine and the
blades are removed.
(2) For the purpose of this AD, piece-part exposure means that
the part is removed from the engine and completely disassembled.
(h) Alternative Methods of Compliance (AMOCs)
The Manager, Engine Certification Office, FAA, may approve AMOCs
for this AD. Use the procedures found in 14 CFR 39.19 to make your
request.
(i) Related Information
For more information about this AD, contact James Gray,
Aerospace Engineer, Engine Certification Office, FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington,
MA; phone: 781-238-7742; fax: 781-238-7199; email:
james.e.gray@faa.gov.
(j) Material Incorporated by Reference
None.
Issued in Burlington, Massachusetts, on September 20, 2012.
Diane M. Cook,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 2012-23791 Filed 10-2-12; 8:45 am]
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