[Federal Register Volume 68, Number 5 (Wednesday, January 8, 2003)]
[Proposed Rules]
[Pages 1016-1017]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-330]


 ========================================================================
 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. 68, No. 5 / Wednesday, January 8, 2003 / 
Proposed Rules  

[[Page 1016]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NE-24-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-6 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The Federal Aviation Administration (FAA) proposes to adopt a 
new airworthiness directive (AD) that is applicable to General Electric 
(GE) CF6-6 series turbofan engines. This proposal would require a 
reduction of the cyclic life limit for certain high pressure turbine 
rotor (HPTR) rear shafts, and would require removing certain HPTR rear 
shafts from service before exceeding the new, lower cyclic life limit. 
In addition, the proposal would require removing from service certain 
HPTR rear shafts that currently exceed, or will exceed, the new, lower 
cyclic life limit according to the compliance schedule described in 
this proposal. The actions specified by the proposed AD are intended to 
prevent cracks in HPTR rear shafts that could result in uncontained 
engine failure and damage to the airplane.

DATES: Comments must be received by March 10, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 2002-NE-24-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location, by appointment, between 8 a.m. and 4:30 p.m., Monday 
through Friday, except Federal holidays. 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.

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, e-mail: [email protected].

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 2002-NE-24-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. 2002-NE-24-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    An updated low-cycle fatigue (LCF) analysis of certain HPTR rear 
shaft part numbers installed in CF6-6 engines, including an improved 3D 
finite element analysis of certain features, was performed by the 
manufacturer. That analysis indicated the need to lower the cyclic life 
limit for these part numbers. The updated analysis was prompted by a 
recently completed analysis on the same rotor assembly, but with 
different blades.
    This proposal will require a new life limit for these HPTR rear 
shaft P/N's of 8,950 cycles-since-new. On August 8, 2002, the 
manufacturer issued Temporary Revision TR 05-0022, revising the life 
limits section of the engine manual to reflect the new life limit for 
these shafts. Because the fleet contains rear shafts that exceed this 
new lower limit, a draw down plan is required. This condition, if not 
corrected could result in LCF cracking and failure of the shafts, which 
could result in uncontained engine failure and damage to the airplane.

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 GE CF6-6 series turbofan engines of the same 
type design, the proposed AD would establish a new, lower cyclic life 
limit of 8,950 CSN for HPTR rear shafts P/N's 9137M13G01/G02/G03, 
9138M22G01/G02/G09/G10, 9138M25G02, and 9687M22G04/G07/G10 and would 
require removing certain HPTR rear shafts from service before exceeding 
the new, lower cyclic life limit. In addition, the proposal would 
require removing from service certain HPTR rear shafts that currently 
exceed, or will exceed, the new, lower cycle life limit according to a 
compliance schedule based on accumulated cycles on the rear shaft on 
the effective date of this AD.

Economic Analysis

    There are approximately 55 GE CF6-6 series turbofan engines of the 
affected design in the domestic fleet that would be affected by this 
proposed AD. There are no foreign registered engines. There are no 
labor or parts costs associated with the implementation of this 
proposed action. The total cost of the proposed AD to U.S. operators is

[[Page 1017]]

estimated to be $41,690 per engine, which is the cost of new rear 
shafts.

Regulatory Analysis

    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. 2002-NE-24-AD.

Applicability

    This airworthiness directive (AD) is applicable to General 
Electric Company CF6-6 series turbofan engines. These engines are 
installed on, but not limited to McDonnell Douglas DC-10 series 
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 (e) 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 cracks in high pressure turbine rotor (HPTR) rear 
shafts, which could result in uncontained engine failure and damage 
to the airplane, do the following:
    (a) Remove from service HPTR rear shafts, part numbers (P/N's) 
9137M13G01/G02/G03, 9138M22G01/G02/G09/G10, 9138M25G02, and 
9687M22G04/G07/G10 in accordance with Table 1 as follows:

               Table 1.--HPTR Rear Shaft Removal Schedule
------------------------------------------------------------------------
   If the rear shaft cycles-since-new
 (CSN) on the effective date of this AD     Then remove the rear shaft
                  are:
------------------------------------------------------------------------
(1) Fewer than 5,000 CSN...............  Before exceeding 8,950 CSN
(2) 5,000 CSN or more, but fewer than    Within 3,950 additional cycles-
 8,950 CSN.                               in-service (CIS) from the
                                          effective date of this AD or
                                          before 11,550 CSN, whichever
                                          occurs earlier.
(3) 8,950 CSN or more..................  At next HPTR rear shaft piece
                                          part exposure, or within 2,600
                                          additional cycles-in-service
                                          (CIS), whichever occurs
                                          earlier.
------------------------------------------------------------------------

    (b) After the effective date of this AD, do not install any HPTR 
rear shaft, P/N 9137M13G01/G02/G03, 9138M22G01/G02/G09/G10, 
9138M25G02, or 9687M22G04/G07/G10, that has 8,950 or more CSN into 
an engine.
    (c) Except as provided in paragraph (a) of this AD, this action 
establishes a new, cyclic life limit of 8,950 CSN for HPTR rear 
shaft P/N's 9137M13G01/G02/G03, 9138M22G01/G02/G09/G10, 9138M25G02, 
and 9687M22G04/G07/G10 which is published in Chapter 05-11-03 of 
CF6-6 Engine Shop Manual, GEK 9266.

Definition

    (d) For the purpose of this AD, HPTR rear shaft piece-part 
exposure is defined as complete disassembly of the rear shaft from 
the HPTR structure in accordance with the manufacturer's engine 
manual.

Alternative Methods of Compliance

    (e) 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 must 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.

Special Flight Permits

    (f) Special flight permits may be issued in accordance 
Sec. Sec.  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 done.

    Issued in Burlington, Massachusetts, on January 3, 2003.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 03-330 Filed 1-7-03; 8:45 am]
BILLING CODE 4910-13-P