Document ID: FAA-2011-0278-0010
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: General Electric Co. (GE) GE90-110B1 and GE90-115B Turbofan Engines
Posted Date: 2011-12-30T05:00Z

[Federal Register Volume 76, Number 251 (Friday, December 30, 2011)]
[Rules and Regulations]
[Pages 82103-82105]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-32832]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0278; Directorate Identifier 2010-NE-10-AD; 
Amendment 39-16901; AD 2011-26-11]
RIN 2120-AA64

Airworthiness Directives; General Electric Company (GE) GE90-
110B1 and GE90-115B 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 the 
products listed above, with certain part number (P/N) high-pressure 
compressor (HPC) stages 2-5 spools installed. This AD was prompted by 
an aborted takeoff caused by liberation of small pieces from the HPC 
stages 1-2 seal teeth and two shop findings of cracks in the seal 
teeth. This AD requires eddy current inspection (ECI) or spot 
fluorescent penetrant inspection (FPI) of the stages 1-2 seal teeth of 
the HPC stages 2-5 spool for cracks. This AD only allows installation 
of either HPC stator stage 1 interstage seals that are pregrooved or 
previously worn seals with acceptable wear marks to prevent heavy rubs. 
We are issuing this AD to detect cracks in the HPC stages 1-2 seal 
teeth due to heavy rubs that could result in failure of the seal of the 
HPC stages 2-5 spool, uncontained engine failure, and damage to the 
airplane.

DATES: This AD is effective February 3, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of February 3, 
2012.

ADDRESSES: For service information identified in this proposed AD, 
contact General Electric, GE-Aviation, Room 285, 1 Neumann Way, 
Cincinnati, Ohio 45215; email: geae.aoc@ge.com; phone: (513) 552-3272; 
fax: (513) 552-3329. You may review copies of the referenced 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.

[[Page 82104]]

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 
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, Engine & Propeller Directorate, 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. 
That NPRM published in the Federal Register on May 26, 2011 (76 FR 
30573). That NPRM proposed to require ECI or spot FPI of the stages 1-2 
seal teeth of the HPC stages 2-5 spool for cracks and to prohibit 
installation of HPC stator stage 1 interstage seals that are not 
pregrooved to prevent heavy rubs.

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.

Remove Reference to ``Uncontained Engine Failure and Damage to the 
Airplane''

    Two commenters, Boeing Company (Boeing) and GE, wanted us to remove 
the reference to ``uncontained engine failure, and damage to the 
airplane'' from the Summary and Unsafe Condition paragraphs. GE claimed 
that all instances to date of material liberation have been contained. 
The commenters further stated that it has been demonstrated that once 
the crack reaches the aft tooth, it turns circumferentially, which 
minimizes the amount of material liberated.
    We disagree. While all of the fractures to date have resulted in 
small pieces that are contained by the engine case, the direction that 
the crack will propagate cannot be determined with great certainty. 
Cracks propagating into the seal will result in a more substantial 
failure of the HPC stages 1-2 seal. Historical experience has shown 
that catastrophic failure of critical rotating engine parts can result 
in an uncontained engine failure that can damage the airplane. We did 
not change the AD based on this comment.

Request Change to Service Bulletin Reference

    Two commenters, Boeing and GE, requested that we change the 
``Previous Credit'' section by replacing ``SB GE90-100 S/B 72-0320, 
Revision 01, dated May 11, 2010 or earlier revision'' with ``SB GE90-
100 S/B 72-0320, Revision 02, dated October 1, 2010, or earlier 
version.'' The commenters indicated that the NPRM (76 FR 30573, May 26, 
2011) mandates accomplishment of GE Service Bulletin (SB) GE90-100 S/B 
72-0320, Revision 02, dated October 1, 2010, and therefore it would be 
consistent to provide credit for accomplishment of GE SB GE90-100 S/B 
72-0320, Revision 02, dated October 1, 2010, or an earlier revision.
    We agree. We changed the reference in the service bulletin to 
Revision 02 in the Previous Credit paragraph.

Request To Allow Reinstallation of Previously Worn Seals

    Three commenters, FedEx, Japan Airlines and All Nippon Airways, 
requested that the FAA allow the installation of previously worn seals. 
Use of these seals is allowed by GE SB GE90-100 S/B 72-0360.
    We agree. We replaced the Installation Prohibition paragraph in the 
AD with a new paragraph called ``Installation of HPC Stator Stage 1 
Interstage Seals'' to allow for the installation of previously worn 
seals. Refer to GE SB GE90-100 S/B 72-360, Revision 04, dated November 
7, 2011, for seals eligible for installation.

Request Change in Installation Prohibition Section

    FedEx requested that wording in the ``Installation Prohibition'' 
section that states ``do not install any HPC forward case unless it has 
an HPC stator stage 1 interstage seals, P/N 351-109-503-0'' be changed 
to ``allow the installation of previously worn seals and/or potential 
future (post-SB 72-0358) interstage seal configurations.'' FedEx 
indicated that the current wording unnecessarily prohibits the 
installation of any forthcoming design improvements to the interstage 
seals that GE might develop.
    We partially agree. We agree with use of a previously worn 
interstage seal because a worn interstage seal could prevent the HPC 
stages 2-5 spool from cracking. We disagree with use of the phrase 
``potential future (post-SB 72-0358) interstage seal configurations'' 
because the AD compliance section can only mandate the use of currently 
approved designs. We added a new paragraph called ``Installation of HPC 
Stator Stage 1 Interstage Seals,'' which allows for the installation of 
previously worn seals.

Remove Reference to Pregrooved Seals

    GE stated that the AD requires the HPC module be reassembled with 
pregrooved seals. GE indicated that this requirement to use pregrooved 
seals is beyond the inspection requirements in GE90-100 S/B 72-0320. GE 
said that the inclusion of pregrooved seal references would cause 
disagreement with the ``Relevant Service Information'' and ``Previous 
Credit'' paragraphs which refer only to the inspection requirement in 
GE90-100 S/B 72-0320.
    We disagree. This AD is issued to mitigate a safety issue caused by 
failure of the HPC stages 2-5 spool stages 1-2 seal. Reassembling the 
HPC module with a pregrooved seal would prevent the heavy rubs that 
result in HPC stages 2-5 spool stages 1-2 seal failure. We did not 
change the AD based on this comment.

Request Correction to Address

    GE requested that its address in the Addresses paragraph be revised 
to correct a missing space.
    We agree. We corrected the GE address in the Addresses paragraph of 
the AD.

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 and minor editorial 
changes. We have determined that these minor changes:
     [Agr]re consistent with the intent that was proposed in 
the NPRM (76 FR 30573, May 26, 2011) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (76 FR 30573, May 26, 2011).
    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 19 GE90-110B1 and GE90-115B 
engines installed on airplanes of U.S. registry. We also estimate that 
it will take about

[[Page 82105]]

2 work-hours per engine to perform the proposed actions, and that the 
average labor rate is $85 per work-hour. Required parts will cost about 
$9,857 per engine. Based on these figures, we estimate the total cost 
of this AD to U.S. operators to be $190,513.

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, 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):

2011-26-11 General Electric Company: Amendment 39-16901; Docket No. 
FAA-2011-0278; Directorate Identifier 2010-NE-10-AD.

(a) Effective Date

    This AD is effective February 3, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) GE90-110B1 and 
GE90-115B turbofan engines with high-pressure compressor (HPC) 
stages 2-5 spool, part number (P/Ns) 351-103-106-0, 351-103-107-0, 
351-103-108-0, 351-103-109-0, 351-103-141-0, 351-103-142-0, 351-103-
143-0, or 351-103-144-0, installed.

(d) Unsafe Condition

    This AD was prompted by an aborted takeoff caused by liberation 
of small pieces from HPC stages 1-2 seal teeth and two shop findings 
of cracks in the seal teeth. We are issuing this AD to detect cracks 
in the HPC stages 1-2 seal teeth due to heavy rubs that could result 
in failure of the seal of the HPC stages 2-5 spool, uncontained 
engine failure, and damage to the airplane.

(e) Compliance

    Comply with this AD when the HPC forward case half is removed 
from the engine after the effective date of this AD, unless the 
actions have already been done.

(f) Inspection

    Perform an eddy current inspection (ECI) or a fluorescent 
penetrant inspection (FPI) of the HPC stages 1-2 seal teeth using 
paragraphs 3.B. or 3.C. of GE Service Bulletin (SB) GE90-100 S/B 72-
0320, Revision 02, dated October 1, 2010.

(g) Remove Cracked Spools

    Remove from service HPC stages 2-5 spool with cracked stages 1-2 
seal teeth before further flight.

(h) Previous Credit

    An ECI or FPI inspection performed before the effective date of 
this AD using GE SB GE90-100 S/B 72-0320, Revision 02, dated October 
1, 2010, or earlier revision, satisfies the inspection requirement 
of this AD.

(i) Installation of HPC Stator Stage 1 Interstage Seals

    (1) After the effective date of this AD, do not install or 
reinstall any HPC forward case unless it is equipped with either:
    (i) HPC stator stage 1 interstage seals, P/N 351-109-503-0;
    (ii) HPC stator stage 1 interstage seals, P/N 351-109-502-0, 
with the grooves on seals that meet the dimensional requirements 
defined in paragraph 3.D.(1) of GE SB GE90-100 S/B 72-360, Revision 
04, dated November 7, 2011.
    (iii) A mixture of the HPC stator stage 1 interstage seals 
listed in paragraphs (i)(1)(i) and (i)(1)(ii) of this AD.

(j) Alternative Methods of Compliance (AMOCs)

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

(k) Related Information

    (1) Contact Jason Yang, Aerospace Engineer, Engine Certification 
Office, FAA, Engine & Propeller Directorate, 12 New England 
Executive Park, Burlington, MA 01803; phone: (781) 238-7747; fax: 
(781) 238-7199; email: jason.yang@faa.gov, for more information 
about this AD.
    (2) GE Service Bulletins GE90-100 S/B 72-0320, Revision 02, 
dated October 1, 2010, and GE90-100 S/B 72-0360, Revision 04, 
November 7, 2011, pertain to the subject of this AD. Contact General 
Electric, GE-Aviation, Room 285, 1 Neumann Way, Cincinnati, Ohio 
45215; email: geae.aoc@ge.com; phone: (513) 552-3272; fax: (513) 
552-3329; for a copy of this service information.

(l) Material Incorporated by Reference

    (1) You must use the following service information to do the 
actions required by this AD, unless the AD specifies otherwise. The 
Director of the Federal Register approved the incorporation by 
reference (IBR) under 5 U.S.C. 552(a) and 1 CFR part 51 of the 
following service information:
    (i) General Electric Company (GE) Service Bulletin (SB) GE90-100 
S/B 72-0320, Revision 02, October 1, 2010; and
    (ii) GE SB GE90-100 S/B 72-0360, Revision 04, dated November, 7, 
2011.
    (2) For service information identified in this AD, contact 
General Electric, GE-Aviation, Room 285, 1 Neumann Way, Cincinnati, 
Ohio 45215; email: geae.aoc@ge.com; phone: (513) 552-3272; fax: 
(513) 552-3329.
    (3) You may review copies of the referenced 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.
    (4) You may also review copies of the service information 
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: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on December 15, 2011.
Thomas A. Boudreau,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-32832 Filed 12-29-11; 8:45 am]
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