[Federal Register Volume 70, Number 160 (Friday, August 19, 2005)]
[Proposed Rules]
[Pages 48660-48661]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-16452]



[[Page 48660]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-22124; Directorate Identifier 2005-NE-21-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-45A, CF6-
50A, CF6-50C, and CF6-50E Series Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for General Electric Company (GE) CF6-45A, CF6-50A, CF6-50C, and CF6-
50E series turbofan engines. This proposed AD would require removing 
from service pre-GE Service Bulletin (SB) No. CF6-50 S/B 72-1268 
configuration low pressure turbine (LPT) stage 2 interstage seal 
assemblies and stage 3 interstage seal assemblies. The proposed AD 
would also require installing new or reworked configuration stage 2 
interstage seal assemblies and stage 3 interstage seal assemblies. This 
proposed AD results from reports of fan mid shaft separation, leading 
to separation of the LPT stage 1 disk, disk overspeed, and uncontained 
engine failure. We are proposing this AD to prevent uncontained engine 
failure and damage to the airplane.

DATES: We must receive any comments on this proposed AD by October 18, 
2005.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact General Electric Company via Lockheed Martin Technology 
Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 45215, 
telephone (513) 672-8400, fax (513) 672-8422, for the service 
information identified in this proposed AD.

    You may examine the comments on this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Karen Curtis, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; telephone (781) 238-
7192; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send us any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-22124; 
Directorate Identifier 2005-NE-21-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of the 
Docket Management System (DMS) web site, anyone can find and read the 
comments in any of our dockets. This includes the name of the 
individual who sent the comment (or signed the comment on behalf of an 
association, business, labor union, etc.). You may review the DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, any comments 
received and, any final disposition in person at the DMS Docket Office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the DMS receives them.

Discussion

    Since 1975, there have been 13 reports of fan mid shaft separation 
in GE CF6-45A, CF6-50A, CF6-50C, and CF6-50E series turbofan engines. 
Two of these separations resulted in disk separation and uncontained 
engine failure. Another of these separations resulted in partial cut-
through of the stage 1 disk spacer arm. On December 3, 1998, the 
National Transportation Safety Board issued Safety Recommendation No. 
A-98-125, to require GE to modify the engines to eliminate the cause of 
these uncontained engine failures. GE performed an extensive 
investigation which revealed that when a fan mid shaft separates, early 
contact and heavy rubbing of the stage 2 interstage seal assembly and 
stage 3 interstage seal assembly occurs with the stage 1 disk spacer 
arms. This heavy rubbing leads to separation of the LPT stage 1 disk, 
disk overspeed, and uncontained engine failure. The axial length of the 
current configuration seals, and their honeycomb density are the cause 
for the early contact and heavy rubbing. When a fan mid shaft 
separates, the intended failure sequence is for the LPT blade airfoils 
to be fragmented by contact with the LPT nozzles, causing the LPT rotor 
to decelerate, preventing uncontained engine failure. This condition, 
if not corrected, could result in uncontained engine failure and damage 
to the airplane. As corrective action, GE has introduced a redesigned 
stage 2 interstage seal assembly configuration and a redesigned stage 3 
interstage seal assembly configuration that have a reduced axial length 
and a lower density honeycomb.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other products 
of this same type design. We are proposing this AD, which would 
require:
     Removal from service of the pre-SB No. CF6-50 S/B 72-1268 
configuration LPT stage 2 interstage seal assembly.
     Installation of a new or reworked configuration LPT stage 
2 interstage seal assembly, part number (P/N) 9198M81G05, 2092M13G01, 
2092M13G02, or 2092M13G03, or other FAA-approved equivalent part.
     Removal from service of the pre-SB No. CF6-50 S/B 72-1268 
configuration stage 3 interstage seal assembly.

[[Page 48661]]

     Installation of a new or reworked configuration stage 3 
interstage seal assembly, P/N 9044M29G17 or 2092M14G01, or other FAA-
approved equivalent part.
    These actions would be required at the next disassembly of the LPT 
stage 2 interstage seal assembly and stage 3 interstage seal assembly 
from the LPT stator after the effective date of the proposed AD, but no 
later than December 31, 2010.

Costs of Compliance

    There are about 2,079 CF6-45A, CF6-50A, CF6-50C, and CF6-50E series 
turbofan engines of the affected design in the worldwide fleet. We 
estimate that 790 engines installed on airplanes of U.S. registry would 
be affected by this proposed AD. We also estimate that it would take 
about 5 work hours per engine to rework the stage 2 interstage seal 
assembly and the stage 3 interstage seal assembly. The average labor 
rate is $65 per work hour. We estimate that 90% of the affected engines 
will have the parts reworked, and 10% will have new parts installed. A 
new stage 2 interstage seal assembly and new stage 3 interstage seal 
assembly would cost about $26,758 per engine. Based on these figures, 
we estimate the total cost of the proposed AD to U.S. operators to be 
$2,344,957.

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 proposed 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 proposed 
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 have 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 that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration 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:

General Electric Company: Docket No. FAA-2005-22124; Directorate 
Identifier 2005-NE-21-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by October 18, 
2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to General Electric Company (GE) CF6-45A, 
CF6-50A, CF6-50C, and CF6-50E series turbofan engines. These engines 
are installed on, but not limited to, Boeing DC10 and 747 series 
airplanes, and Airbus Industrie A300 series airplanes.

Unsafe Condition

    (d) This AD results from reports of fan mid shaft separation, 
leading to separation of the LPT stage 1 disk, disk overspeed, and 
uncontained engine failure. We are issuing this AD to prevent 
uncontained engine failure and damage to the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed at the next disassembly of the low pressure turbine 
(LPT) stage 2 interstage seal assembly and stage 3 interstage seal 
assembly from the LPT stator after the effective date of this AD, 
but no later than December 31, 2010, unless the actions have already 
been done.

Stage 2 Interstage Seal Assemblies

    (f) Remove from service the pre-GE Service Bulletin (SB) No. 
CF6-50 72-1268 configuration LPT stage 2 interstage seal assembly.
    (g) Install a new or reworked configuration LPT stage 2 
interstage seal assembly, part number (P/N) 9198M81G05, 2092M13G01, 
2092M13G02, or 2092M13G03, or other FAA-approved equivalent part.
    (h) Information on reworking the pre-SB No. CF6-50 S/B 72-1268 
configuration stage 2 interstage seal assembly to the new 
configuration can be found in GE SB No. CF6-50 S/B 72-1268, dated 
December 16, 2004.

Stage 3 Interstage Seal Assemblies

    (i) Remove from service the pre-SB No. CF6-50 S/B 72-1268 
configuration stage 3 interstage seal assembly.
    (j) Install a new or reworked configuration LPT stage 3 
interstage seal assembly, P/N 9044M29G17 or 2092M14G01, or other 
FAA-approved equivalent part.
    (k) Information on reworking the pre-SB No. CF6-50 S/B 72-1268 
configuration stage 3 interstage seal assembly to the new 
configuration can be found in GE SB No. CF6-50 S/B 72-1268, dated 
December 16, 2004.

Prohibition of Pre-SB No. CF6-50 S/B 72-1268 Configurations

    (l) After the effective date of this AD, do not install pre-SB 
No. CF6-50 S/B 72-1268 configuration LPT stage 2 interstage seal 
assemblies or stage 3 interstage seal assemblies into any engine.

Alternative Methods of Compliance

    (m) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (n) National Transportation Safety Board Safety Recommendation 
No. A-98-125, dated December 3, 1998, pertains to the subject of 
this AD.

    Issued in Burlington, Massachusetts, on August 12, 2005.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 05-16452 Filed 8-18-05; 8:45 am]
BILLING CODE 4910-13-P