[Federal Register Volume 66, Number 96 (Thursday, May 17, 2001)]
[Proposed Rules]
[Pages 27475-27476]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-12425]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 66, No. 96 / Thursday, May 17, 2001 / 
Proposed Rules  

[[Page 27475]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NE-19-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-50 and 
CF6-80C2 Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) proposes to adopt a 
new airworthiness directive (AD) that is applicable to General Electric 
Company CF6-50 and CF6-80C2 turbofan engines. This proposal would 
require replacement of certain existing CF6-50 and CF6-80C2 shrouds 
with new design shrouds. This proposal is prompted by 37 low pressure 
turbine (LPT) uncontained events on the CF6-50 and 24 on the CF6-80C2 
engine models since 1993, and the development and certification of 
newly designed shrouds that will improve LPT containment capability. 
The actions specified by the proposed AD are intended to prevent 
uncontained engine failure and possible airplane damage.

DATES: Comments must be received by July 16, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 2001-NE-19-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``[email protected]''. Comments sent via the Internet must contain the 
docket number in the subject line. Comments may be inspected at this 
location between 8 a.m. and 4:30 p.m., Monday through Friday, except 
Federal holidays. The service information referenced in the proposed 
rule may be obtained from General Electric Company via Lockheed Martin 
Technology Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 
45215, telephone: (513) 672-8400; fax: (513) 672-8422. This information 
may be examined at the FAA, New England Region, Office of the Regional 
Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Karen Curtis, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone: (781) 
238-7192, fax: (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NE-19-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRM's

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 2001-NE-19-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    Since 1993, the General Electric CF6 turbofan engine has 
experienced a number of low pressure turbine (LPT) failures in which 
debris from the engine has escaped from the engine case and nacelle. 
The engine shroud is part of the containment system intended to prevent 
such debris from an LPT failure from threatening the aircraft. For the 
CF6-50 engine model, there have been 16 such events where the debris 
escaped the engine case, 12 where the debris escaped both the case and 
nacelle, and nine where the debris escaped the case and nacelle and 
impacted the aircraft. The CF6-80C2 has experienced 16 events where the 
debris escaped the engine case, six where the debris escaped the case 
and nacelle, and two where the debris impacted the aircraft.
    Many different upstream failures have led to the secondary breakup 
and separation of LPT blades, and resulted in low energy LPT case 
penetrations. High pressure turbine (HPT) blade failures, HPT nozzle 
failures, and fan mid shaft separations due to high pressure compressor 
airduct failures have been the leading causes for uncontained LPT 
failures for these engine models. In addition, multiple shroud repairs 
can lead to reduced shroud backsheet thickness and result in reduced 
containment system capability.
    The manufacturer has developed, and the FAA has certified, newly 
designed shrouds that will improve LPT contaiment capability and 
enhance engine safety. Although the manufacturer and the FAA have also 
designed and certified design improvements to address the known 
upstream failure modes, not all such failure modes can be anticipated 
and therefore improved LPT containment capability is necessary to 
protect the airplane from debris from an LPT failure, and enhance 
safety for these engine models.
    This proposal would require replacement of certain existing CF6-50 
and CF6-80C2 shrouds with new design shrouds.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of GE 
Aircraft

[[Page 27476]]

Engines Service Bulletin (GEAE SB) CF6-80C2 S/B 72-1006, dated April 
11, 2001 and GEAE SB CF60-50 S/B 72-1170, dated May 7, 1999, that 
specify part numbers and procedures for the removal and replacement of 
the shrouds.

FAA's Determination of an Unsafe Condition and Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other General Electric Company CF6-50 and CF6-80C2 
turbofan engines of the same type design, the proposed AD would require 
replacement of certain existing CF6-50 and CF6-80C2 shrouds with new 
design shrouds at the next shroud piece part exposure, but no later 
than December 31, 2006. The actions would be required to be 
accomplished in accordance with the service bulletins described 
previously.

Economic Impact

    There are approximately 5,055 GE CF6-50 and CF6-80C2 turbofan 
engines of the affected design in the worldwide fleet. The FAA 
estimates that 1,106 engines installed on airplanes of U.S. registry 
would be affected by this proposed AD. Because this proposal calls for 
the replacement of shrouds at piece part exposure, the FAA does not 
expect that additional labor costs will be accrued beyond that normally 
required to remove the existing shroud. New shrouds will cost 
approximately $63,250 for the CF6-50 engines, and $87,020 for the CF6-
80C2 engines. Based on these figures, the total cost to retrofit all 
installed US registered engines is estimated to be $85,096,038 over a 
five year period, or $17,019,207 annually.

Regulatory Impact

    This proposed rule does not have federalism implications, as 
defined in Executive Order 13132, because it 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. 
Accordingly, the FAA has not consulted with state authorities prior to 
publication of this proposed rule.
    For the reasons discussed above, I certify that 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); 
and (3) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new 
airworthiness directive:

General Electric Company: Docket No. 2001-NE-19-AD.
    Applicability: This airworthiness directive (AD) is applicable 
to General Electric Company (GE) CF6-50 and CF6-80C2 turbofan 
engines These engines are installed on, but not limited to DC-10-15, 
DC-10-30, MD11, 747, 767, A300 and A310 airplanes.

    Note 1: This AD applies to each engine identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For engines that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Compliance with this AD is required as indicated, 
unless already done. To prevent uncontained engine failure and 
possible airplane damage, do the following:
    (a) Remove existing Stage 2, 3 and 4 low pressure turbine (LPT) 
CF6-80C2 shrouds and replace with new design part numbers (P/N's) 
2083M12G01, 2083M13G01, and 2083M14G01, respectively, in accordance 
with GE Aircraft Engines Service Bulletin (GEAE SB) CF6-80C2 S/B 72-
1006, dated April 11, 2001, at the next shroud piece part exposure, 
but no later than December 31, 2006.
    (b) Remove existing Stage 1, 2, 3 and 4 LPT CF6-50 shrouds and 
replace with new design P/N's 1822M35G01, 1822M36G01, 1822M36G02, 
and 1822M37G01, respectively, in accordance with GEAE SB CF6-50 S/B 
72-1170, dated May 7, 1999, at the next shroud piece part exposure, 
but no later than December 31, 2006.

Alternative Methods of Compliance

    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Engine Certification Office (ECO). 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

    (d) Special flight permits may be issued in accordance 
Secs. 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 
requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on May 11, 2001.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-12425 Filed 5-16-01; 8:45 am]
BILLING CODE 4910-13-P