[Federal Register Volume 66, Number 210 (Tuesday, October 30, 2001)]
[Proposed Rules]
[Pages 54731-54733]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-27191]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NE-33-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company (GE) CF6-45 
and CF6-50 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 GE CF6-45 and 
CF6-50 series turbofan engines. This proposal would require a reduction 
of the cyclic life limit for certain low pressure turbine rotor (LPTR) 
stage 2 disks, and would require removing certain LPTR stage 2 disks 
from service before exceeding the new, lower cyclic life limit. In 
addition, the proposal would require removing from service certain LPTR 
stage 2 disks that currently exceed, or will exceed, the new, lower 
cyclic life limit according to the compliance schedule described in 
this proposal. This proposal is prompted by a report of a cracked LPTR 
stage 2 disk found during a visual inspection. The actions specified by 
the proposed AD are intended to prevent an uncontained engine failure 
and damage to the airplane, resulting from cracks in the LPTR stage 2 
disk.

DATES: Comments must be received by December 31, 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-33-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected, 
by appointment, at this location 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: Ann Mollica, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7740; 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

[[Page 54732]]

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-33-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-33-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    An LPTR stage 2 disk cracked in the forward slot area was 
discovered during a shop visit visual inspection. The manufacturer has 
determined that the crack is a result of low cycle fatigue failure. As 
a result, the manufacturer has reevaluated the 15,500 cycles-since-new 
(CSN) cyclic life limit for LPTR stage 2 disks part numbers (P/N's) 
9061M22P08 and 9061M22P10, and has recalculated the cyclic life limit. 
This proposal would establish a new, lower cyclic life limit of 10,400 
CSN for LPTR stage 2 disks P/N's 9061M22P08 and 9061M22P10 and would 
require removing certain LPTR stage 2 disks from service before 
exceeding the new, lower cyclic life limit. In addition, the proposal 
would require removing from service certain LPTR stage 2 disks that 
currently exceed, or will exceed, the new, lower cyclic life limit 
according to a compliance schedule based on accumulated cycles on the 
disk on the effective date of the AD. The compliance schedule is 
established on the basis of a risk analysis that the FAA has reviewed. 
The FAA has determined that the compliance schedule based on that risk 
analysis establishes an acceptable level of safety for those disks 
operated beyond the new life limit. The actions specified by the 
proposed AD are intended to prevent an uncontained engine failure and 
damage to the airplane, resulting from cracks in the LPTR stage 2 disk.

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 CF6-45 and CF6-50 series turbofan engines 
of the same type design, the proposed AD would establish a new, lower 
cyclic life limit of 10,400 CSN for LPTR stage 2 disks 
P/N's 9061M22P08 and 9061M22P10 and would require removing certain LPTR 
stage 2 disks from service before exceeding the new, lower cyclic life 
limit. In addition, the proposal would require removing from service 
certain LPTR stage 2 disks that currently exceed, or will exceed, the 
new, lower cycle life limit according to a compliance schedule based on 
accumulated cycles on the disk on the effective date of this AD.

Economic Analysis

    There are approximately 1,376 GE CF6-45 and CF6-50 series turbofan 
engines of the affected design in the worldwide fleet. The FAA 
estimates that 664 engines installed on airplanes of U.S. registry 
would be affected by this proposed AD. The proposed action does not 
impose any additional labor costs. A new disk would cost approximately 
$72,870 per engine. Based on these figures, and on the prorating for 
the usage of the disks, the cost effect of the proposed AD on U.S. 
operators is estimated to be $10,385,724.

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. 2001-NE-33-AD.

    Applicability: This airworthiness directive (AD) is applicable 
to General Electric Company (GE) CF6-45 and CF6-50 series turbofan 
engines. These engines are installed on, but not limited to, Airbus 
Industrie A300 series, Boeing 747 series, and 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 an uncontained engine failure and damage to the 
airplane, resulting from cracks in the low pressure turbine rotor 
(LPTR) stage 2 disk, do the following:
    (a) Remove from service LPTR stage 2 disks, part numbers (P/N's) 
9061M22P08 and 9061M22P10 in accordance with Table 1 as follows:

[[Page 54733]]



              Table 1.--LPTR Stage 2 Disk Removal Schedule
------------------------------------------------------------------------
 If disk cycles-since-new (CSN) on the
     effective date of this AD are:             Then remove disk:
------------------------------------------------------------------------
(1) Fewer than 5,300 CSN...............  Before exceeding 10,400 CSN.
(2) 5,300 CSN or more, but fewer than    Within 5,100 additional cycles-
 10,400 CSN.                              in-service from the effective
                                          date of this AD.
(3) 10,400 CSN or more.................  At next LPTR stage 2 disk
                                          exposure, or by 15,500 CSN,
                                          whichever occurs earlier.
------------------------------------------------------------------------

    (b) After the effective date of this AD, do not install any LPTR 
stage 2 disk, P/N 9061M22P08 or 9061M22P10, that has 10,400 or more 
CSN into an engine.
    (c) Except for as provided in paragraph (a) of this AD, this 
action establishes a new, cyclic life limit of 10,400 CSN for LPTR 
stage 2 disk, P/N 9061M22P08 and 9061M22P10, which is published in 
Chapter 05-10-00 of CF6-45 and CF6-50 Engine Shop Manual, GEK 50481.

Definition

    (d) For the purpose of this AD, LPTR stage 2 disk exposure is 
defined as disassembly and removal of the LPTR stage 2 disk from the 
LPTR structure, regardless of whether any blades, bolts, nuts, bolt 
retainers, blade retainers, blade inserts, balance weights, wear 
strips, or seals remain assembled to the disk.

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 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the aircraft to a location where the 
requirements of this AD can be done.

    Issued in Burlington, Massachusetts, on October 22, 2001.
Thomas Boudreau,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-27191 Filed 10-29-01; 8:45 am]
BILLING CODE 4910-13-P