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[Federal Register Volume 75, Number 245 (Wednesday, December 22, 2010)]
[Proposed Rules]
[Pages 80370-80372]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-32156]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-1024; Directorate Identifier 2010-NE-34-AD]
RIN 2120-AA64

Airworthiness Directives; General Electric Company GE90-76B; 
GE90-77B; GE90-85B; GE90-90B; and GE90-94B Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for the 
products listed above. This proposed AD would require initial and 
repetitive fluorescent penetrant inspections (FPIs) and eddy current 
inspections (ECIs) of the high-pressure compressor rotor (HPCR) 8-10 
stage spool, part numbers (P/Ns) 1844M90G01 and 1844M90G02, for cracks 
between the 9-10 stages, at each piece-part exposure. This proposed AD 
was prompted by cracks discovered on one HPCR 8-10 spool between the 9-
10 stages in the weld joint. We are proposing this AD to prevent 
failure of the HPCR 8-10 stage spool, uncontained engine failure, and 
damage to the airplane.

DATES: We must receive comments on this proposed AD by February 7, 
2011.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be

[[Page 80371]]

available in the AD docket shortly after receipt.

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; e-mail: 
jason.yang@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2010-1024; 
Directorate Identifier 2010-NE-34-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    General Electric Company (GE) recently informed us of cracks 
discovered during a shop visit of a GE90-94B turbofan engine. The 
cracks were in the HPCR 8-10 stage spool weld joint between the 9-10 
stages. These cracks can lead to failure of the HPCR 8-10 stage spool. 
GE informed us that the cracking is caused by defects during part 
manufacture, in the inertia weld process. This unsafe condition could 
also occur on GE90-76B; GE90-77B; GE90-85B; and GE90-90B turbofan 
engines, as they use the same design HPCR 8-10 stage spool. GE90 Engine 
Manual Chapter 5 requires mandatory inspections of the HPCR 8-10 stage 
spool, specifically, inspection of the weld joint between the 8-9 
stages. Because of the cracking between the 9-10 stages in the weld 
joint, GE has updated Chapter 5 to include inspection of the weld joint 
between the 9-10 stages. They also changed the inertia weld process 
during manufacture. These cracks, if not corrected, could result in 
failure of the HPCR 8-10 stage spool, uncontained engine failure, and 
damage to the airplane.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would require initial and repetitive FPIs and ECIs 
of the HPCR 8-10 stage spool, P/Ns 1844M90G01 and 1844M90G02 for 
cracks, at each piece-part exposure.

Costs of Compliance

    We estimate that this proposed AD would affect 33 GE90-76B; GE90-
77B; GE90-85B; GE90-90B; and GE90-94B engines installed on airplanes of 
U.S. registry. We also estimate that it would take about 2 work-hours 
per engine to perform one proposed inspection, and that the average 
labor rate is $85 per work-hour. Based on these figures, we estimate 
the total cost of the proposed AD to U.S. operators to be $5,610 for 
one inspection cycle.

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

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979),
    (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, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

General Electric Company: Docket No. FAA-2010-1024; Directorate 
Identifier 2010-NE-34-AD.

Comments Due Date

    (a) We must receive comments by February 7, 2011.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to General Electric Company GE90-76B; GE90-
77B; GE90-85B; GE90-90B; and GE90-94B turbofan engines with a high-
pressure compressor rotor (HPCR) 8-10 stage spool, part number (P/N) 
1844M90G01 or 1844M90G02, installed. These engines are installed on 
but not limited to Boeing 777 series airplanes.

Unsafe Condition

    (d) This AD was prompted by cracks discovered on one HPCR 8-10 
spool between the 9-10 stages in the weld joint. We are issuing this 
AD to prevent failure of the HPCR 8-10 stage spool, uncontained 
engine failure, and damage to the airplane.

Compliance

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

Inspections of the HPCR 8-10 Stage Spool

    (f) At the next piece-part exposure after the effective date of 
this AD of the HPCR 8-10 stage spool, perform a fluorescent 
penetrant inspection (FPI) and eddy current inspection (ECI) of the 
weld joint between the 9-10 stages of the HPCR 8-10 stage spool for 
cracks.
    (g) Thereafter, perform repetitive FPIs and ECIs of the weld 
joint between the 9-10 stages of the HPCR 8-10 stage spool for

[[Page 80372]]

cracks at every piece-part exposure of the HPCR 8-10 stage spool.
    (h) Remove from service any HPCR 8-10 stage spool found cracked.
    (i) Guidance on performing the FPI can be found in GE90 
(GEK100700) Engine Manual, Chapter 72-31-08, Inspection 001.
    (j) Guidance on performing the ECI can be found in GE90 
(GEK100700) Engine Manual, Chapter 72-31-08, Special Procedures 001.

Definition

    (k) For the purpose of this AD, piece-part exposure is when the 
HPCR stage 8-10 spool is completely disassembled using the 
disassembly instructions in the GE90 Engine Manual.

Alternative Methods of Compliance (AMOCs)

    (l) The Manager, Engine Certification Office, FAA, has the 
authority to approve AMOCs for this AD, if requested using the 
procedures found in 14 CFR 39.19.

Related Information

    (m) 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; e-mail: jason.yang@faa.gov.
    (n) For service information identified in this AD, contact 
General Electric Company, GE--Aviation, Room 285, 1 Neumann Way, 
Cincinnati, OH 45215, telephone 513-552-3272; fax 513-552-3329; e-
mail: geae.aoc@ge.com. For information on the availability of this 
material at the FAA, call 781-238-7125.

    Issued in Burlington Massachusetts, on December 10, 2010.
Peter A. White,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2010-32156 Filed 12-21-10; 8:45 am]
BILLING CODE 4910-13-P
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