
[Federal Register Volume 78, Number 178 (Friday, September 13, 2013)]
[Rules and Regulations]
[Pages 56594-56597]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-22243]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2013-0186; Directorate Identifier 2013-NE-11-AD; 
Amendment 39-17571; AD 2013-17-07]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
General Electric Company (GE) GE90-76B, -85B, -90B, -94B, -110B1, and -
115B turbofan engines. This AD was prompted by multiple reports of 
distress of certain stage 1 high-pressure turbine (HPT) stator shrouds 
due to accelerated corrosion and oxidation, including one engine in-
flight shutdown (IFSD) caused by failure of the HPT stator shrouds. 
This AD requires initial and repetitive on-wing 360-degree borescope 
inspections (BSIs) for corrosion and oxidation of stage 1 HPT stator 
shrouds. If a shroud is found to be distressed, this AD requires 
reinspection at a reduced interval or removal from service before 
further flight. We are issuing this AD to prevent failure of stage 1 
HPT stator shrouds, resulting in an IFSD of one or more engines, loss 
of thrust control, and damage to the airplane.

DATES: This AD is effective October 18, 2013.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of October 18, 
2013.

ADDRESSES: For service information identified in this AD, contact 
General Electric Company, One Neumann Way, MD Y-75, Cincinnati, OH; 
phone: 513-552-2913; email: geae.aoc@ge.com; Web site: www.GE.com. You 
may view this service information at the FAA, Engine & Propeller 
Directorate, 12 New England Executive Park, Burlington, MA. For 
information on the availability of this material at the FAA, call 781-
238-7125.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://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

[[Page 56595]]

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.

FOR FURTHER INFORMATION CONTACT: Jason Yang, Aerospace Engineer, Engine 
Certification Office, FAA, 12 New England Executive Park, Burlington, 
MA 01803; phone: 781-238-7747; fax: 781-238-7199; email: 
jason.yang@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. 
The NPRM published in the Federal Register on April 2, 2013 (78 FR 
19628). The NPRM proposed to require initial and repetitive on-wing 
360-degree BSIs for corrosion and oxidation of stage 1 HPT stator 
shrouds. If a shroud failed the inspection, the NPRM proposed to 
require removal from service before further flight. We are issuing this 
AD to prevent failure of stage 1 HPT stator shrouds, resulting in an 
IFSD of one or more engines, loss of thrust control, and damage to the 
airplane.

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.

Request To Clarify the Inspection Threshold for Compliance

    Austrian Airlines requested that we specify a compliance threshold 
of 2,000 cycles to be in agreement with GE Service Bulletin (SB) No. 
GE90-100 SB 72-0528, dated November 15, 2012, rather than the 2,100 
cycles specified in the NPRM (78 FR 19628, April 2, 2013).
    We disagree. GE SB No. GE90-100 SB 72-0528, dated November 15, 
2012, requires a BSI within 2 months after an engine reaches 2,000 
cycles. We estimate that 2 months of utilization is about 100 cycles, 
which we added to the initial compliance threshold to strengthen 
enforceability and to lessen the impact on operators with engines 
having less than 2,000 cycles. We did not change this AD.

Request for Clarification on Affected Part Numbers

    American Airlines (AAL) commented that since stage 1 HPT stator 
shroud, part number (P/N) 1847M52P16, is included in the NPRM (78 FR 
19628, April 2, 2013), that stage 1 HPT stator shroud, P/N 1847M52P10, 
should also be included.
    We disagree. Our risk analysis determined that corrective actions 
are required for stage 1 HPT stator shroud, P/N 1847M52P16. Although 
stage 1 HPT stator shroud, P/N 1847M52P10, also experienced distress in 
service, the distress was due to a different root cause. We did not 
identify a safety issue associated with the distress associated with 
stage 1 HPT stator shroud, P/N 1847M52P10. We did not change this AD.

Request To Reduce Requirements Due to Service Bulletin Category

    AAL commented that we should not mandate corrective actions in an 
AD since GE did not designate the operable service bulletins as alert 
service bulletins, and therefore GE did not identify stage 1 HPT stator 
shroud distress as a safety issue.
    We disagree. The corrective actions mandated in this AD are based 
on the results of a risk analysis of relevant engine operational safety 
issues. The category of service bulletin issued by GE was not a factor 
in our decision to issue this AD. We did not change this AD.

Request To Change Applicability

    AAL requested that we add GE90 engines that do not have GE SB No. 
GE90-100 SB 72-0348, which introduces a new stage 1 HPT stator shroud 
and new shroud hanger, incorporated, to the applicability of this AD. 
AAL believes that an engine that has GE SB No. GE90-100 SB 72-0348, 
incorporated, does not require repetitive BSIs.
    We disagree. After an engine has GE SB No. GE90-100 SB 72-0348 
incorporated, using shrouds with a new P/N, the engine is not affected 
by this AD. A stage 1 HPT stator shroud P/N not listed in the 
Applicability of this AD is not affected by this AD. We did not change 
this AD.

Request To Use Revised GE SB for Compliance Actions

    AAL requested that paragraph (f)(4)(i) of the AD also reference GE 
SB No. SB 72-0528 R01, Revision 1, dated April 1, 2013, in addition to 
the initial issue of that GE SB.
    We agree. We changed paragraphs (f)(4)(i) and (f)(4)(ii) of this AD 
by adding a reference to GE SB No. SB 72-0528 R01, Revision 1, dated 
April 1, 2013.

Request To Revise Inspection Instructions

    AAL noted that paragraph 3.A. of the Accomplishment Instructions of 
GE SB No. GE90-100 SB 72-0528, dated November 15, 2012, which we refer 
to in the compliance paragraphs of this AD, contain elements that do 
not pertain to this AD, especially elements regarding assembly and 
disassembly. AAL requested that we revise paragraphs (f)(3)(i) and 
(f)(4)(i) of this AD by removing accomplishment elements not related to 
this AD.
    We partially agree. We agree that paragraph 3.A. of the 
Accomplishment Instructions of GE SB No. GE90-100 SB 72-0528, dated 
November 15, 2012, contains some instructions not directly related to 
this AD. We do not agree that they are unrelated service information 
for inspecting and removing a distressed shroud. We changed paragraphs 
(f)(3)(i) and (f)(4)(i) of this AD to refer to paragraph 3.A. of the 
Accomplishment Instructions of the GE SB for guidance on how to perform 
a BSI to detect and remove a distressed shroud.

Request To Detail the Scope of Work for the BSI

    AAL requested that we revise paragraph (f)(4)(ii) of this AD to 
include the scope of work for the BSI.
    We partially agree. We do not agree with including the scope of 
work for the BSI in this AD. We agree to include a reference to the 
paragraphs of the GE SB that detail the scope of work for the BSI to be 
performed for this AD, including how to determine if the shrouds are 
distressed. We changed paragraphs (f)(4)(ii) and (f)(4)(iii) of this AD 
and also paragraphs (f)(3)(ii) and (f)(3)(iii) of this AD accordingly.

Request To Add a Paragraph Summarizing Credit for Previous Actions

    One commenter requested that we add a paragraph granting credit for 
engines previously inspected in accordance with the GE SBs.
    We disagree. Paragraph (e) of this AD already grants credit for 
previous inspections with the statement, ``Comply with this AD within 
the compliance times specified, unless already done.'' We did not 
change this AD.

Request To Clarify Whether Alternate Method of Compliance (AMOC) Is 
Needed

    All Nippon Airways Co., Ltd (ANA) requested clarification as to 
whether use of a locally manufactured BSI guide tube would require an 
AMOC request. ANA noted that using a BSI guide tube facilitates 
insertion of the borescope and does not otherwise affect the procedures 
described in GE SBs.

[[Page 56596]]

    We agree that use of a BSI guide tube facilitates insertion of the 
borescope and does not affect the procedure required by this AD. An 
AMOC is not required to use a BSI guide tube. We did not change this 
AD.

Request To Revise Summary and Unsafe Condition Language

    GE requested that we change the word ``failure'' to ``distress'' in 
the Summary and in paragraph (d) of this AD. GE commented that while 
there have been several reports of distress to the stage 1 HPT stator 
shrouds, there has been only one failure.
    We partially agree. We agree with revising the wording to more 
accurately describe the service history. We disagree with removing the 
word ``failure'' from the Summary paragraph and from paragraph (d) of 
this AD because there has been an IFSD caused by failure of the stage 1 
HPT stator shroud.
    We changed the Summary paragraph and paragraph (d) of this AD to 
include ``distress.''

Request To Change the Proposed AD Requirements Paragraph

    GE requested that we change the Summary and Proposed AD 
Requirements paragraphs by adding the words ``reduced interval 
inspection or . . .'' to more accurately coincide with the intent of GE 
SB No. GE90-100 SB 72-0528.
    We agree. We changed the Summary paragraph of this AD by adding the 
words ``reinspection at a reduced interval or . . .''. The sentence now 
reads, ``If a shroud is found to be distressed, this AD requires 
reinspection at a reduced interval or removal from service before 
further flight.''

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 minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (78 FR 19628, dated April 2, 2013) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (78 FR 19628, dated April 2, 2013).
    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 will affect about 100 GE90 engines 
installed on airplanes of U.S. registry. We also estimate that it will 
take about four hours per engine to perform one inspection. The average 
labor rate is $85 per hour. Based on these figures, we estimate the 
total cost of this AD on U.S. operators for one inspection to be 
$34,000.

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 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 to the extent 
that it justifies making a regulatory distinction, 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):

2013-17-07 General Electric Company: Amendment 39-17571; Docket No. 
FAA-2013-0186; Directorate Identifier 2013-NE-11-AD.

(a) Effective Date

    This AD is effective October 18, 2013.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE):
    (1) GE90-76B, -85B, -90B, and -94B turbofan engines with stage 1 
high-pressure turbine (HPT) stator shrouds, part number (P/N) 
1847M52P14, installed.
    (2) GE90-110B1 and -115B turbofan engines with stage 1 HPT 
stator shrouds, P/N 1847M52P16, installed.

(d) Unsafe Condition

    This AD was prompted by multiple reports of distress of certain 
stage 1 HPT stator shrouds due to accelerated corrosion and 
oxidation, including one engine in-flight shutdown (IFSD) caused by 
failure of the HPT stator shrouds. We are issuing this AD to prevent 
failure of stage 1 HPT stator shrouds, resulting in an IFSD of one 
or more engines, loss of thrust control, and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(f) Borescope Inspections of the Stage 1 HPT Stator Shrouds

    (1) Perform an initial on-wing borescope inspection (BSI) of the 
stage 1 HPT stator shrouds for corrosion and oxidation before 
accumulating 2,100 cycles since new, or within 100 cycles in service 
after the effective date of this AD, whichever occurs later.
    (2) Thereafter, repeat the BSI of the stage 1 HPT stator shrouds 
every 250 cycles since last inspection or fewer, depending on the 
results of the inspection.
    (3) For engines listed in paragraph (c)(1) of this AD:
    (i) Perform a 360-degree BSI of the stage 1 HPT stator shrouds 
for corrosion and oxidation. Guidance for performing the BSI

[[Page 56597]]

can be found in paragraph 3.A of the Accomplishment Instructions of 
GE Service Bulletin (SB) No. GE90 S/B 72-1076, dated November 19, 
2012.
    (ii) Refer to Figure 2 of GE SB No. GE90 S/B 72-1076, dated 
November 19, 2012, to determine the degree of shroud corrosion and 
oxidation.
    (iii) Use paragraph 3.B. of the Accomplishment Instructions of 
GE SB No. GE90 S/B 72-1076, dated November 19, 2012, to determine 
the next inspection interval.
    (4) For engines listed in paragraph (c)(2) of this AD:
    (i) Perform a 360-degree BSI of the stage 1 HPT stator shrouds 
for corrosion and oxidation. Guidance for performing the BSI can be 
found in paragraph 3.A of the Accomplishment Instructions of GE SB 
No. SB 72-0528 R01, Revision 1, dated April 1, 2013, or GE GE90-100 
SB No. SB 72-0528, dated November 15, 2012.
    (ii) Refer to Figure 2 of GE SB No. SB 72-0528 R01, Revision 1, 
dated April 1, 2013, or GE GE90-100 SB No. SB 72-0528, dated 
November 15, 2012, to determine the degree of shroud corrosion and 
oxidation.
    (iii) Use paragraph 3.B. of the Accomplishment Instructions of 
GE SB No. SB 72-0528 R01, Revision 1, dated April 1, 2013, or GE 
GE90-100 SB No. SB 72-0528, dated November 15, 2012, to determine 
the next inspection interval.
    (5) Remove from service before further flight, any stage 1 HPT 
stator shroud found with any hole further than 0.35-inch from the 
shroud leading edge, and more than 0.25-inch in diameter, and that 
is more than 0.049 square inch in area.

(g) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, may approve AMOCs 
for this AD. Use the procedures in 14 CFR 39.19 to make your 
request.

(h) Related Information

    For more information about this AD, contact Jason Yang, 
Aerospace Engineer, Engine Certification Office, FAA, 12 New England 
Executive Park, Burlington, MA 01803; phone: 781-238-7747; fax: 781-
238-7199; email: jason.yang@faa.gov.

(i) 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 this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) General Electric Company (GE) Service Bulletin (SB) No. SB 
72-0528 R01, Revision 1, dated April 1, 2013.
    (ii) GE SB No. GE90-100 SB 72-0528, dated November 15, 2012.
    (iii) GE SB No. GE90 S/B 72-1076, dated November 19, 2012.
    (3) For GE service information identified in this AD, contact 
General Electric Company, One Neumann Way, MD Y-75, Cincinnati, OH; 
phone: 513-552-2913; email: geae.aoc@ge.com; Web site: www.GE.com.
    (4) You may view this service information at the FAA, Engine & 
Propeller Directorate, 12 New England Executive Park, Burlington, 
MA. For information on the availability of this material at the FAA, 
call 781-238-7125.
    (5) You may view this service information 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: 
http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on August 22, 2013.
Dorenda D. Baker,
Director, Aircraft Certification Service.
[FR Doc. 2013-22243 Filed 9-12-13; 8:45 am]
BILLING CODE 4910-13-P


