[Federal Register Volume 64, Number 227 (Friday, November 26, 1999)]
[Proposed Rules]
[Pages 66415-66416]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30804]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-51-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company GE90 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain General Electric Company 
(GE) GE90 series turbofan engines. This proposal would reduce the 
cyclic life limits for certain mid fan shafts with undesirable 
microstructure, and remove from service those mid fan shafts prior to 
exceeding the new limits and replace with serviceable parts. Reports of 
magnetic particle inspections conducted by the manufacturer identifying 
segregation in the raw material, resulting in lower fatigue life 
properties, prompted this proposal. The actions specified by the 
proposed AD are intended to prevent mid fan shaft failure, which could 
result in an uncontained engine failure and damage to the aircraft.

DATES: Comments must be received by December 27, 1999.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 98-ANE-51-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 8:00 a.m. and 4:30 
p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: William S. Ricci, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7742, 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 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 notice 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.

[[Page 66416]]

    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-ANE-51-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    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. 98-ANE-51-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received reports from 
General Electric Company (GE) that the cyclic life limits for certain 
mid fan shafts installed on GE90-90B, -85B, and -76B series turbofan 
engines must be reduced. The manufacturer advises that retained 
austenite has been observed in these mid fan shafts due to segregation 
in the raw material. Material property testing indicates that reduced 
low cycle fatigue (LCF) properties result, requiring reduced life 
limits. This condition, if not corrected, could result in mid fan shaft 
failure, which could result in an uncontained engine failure and damage 
to the aircraft.

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would reduce the cyclic life limits for affected mid fan 
shafts, and remove from service those mid fan shafts prior to exceeding 
the new limits and replace with serviceable parts.

Economic Analysis

    There are approximately 118 engines of the affected design in the 
worldwide fleet. The FAA estimates that 4 engines installed on aircraft 
of US registry would be affected by this proposed AD and that the 
prorated life reduction would cost approximately $71,000 per engine. 
Based on these figures, the total cost impact of the proposed AD on US 
operators is estimated to be $284,000.

Regulatory Impact

    This proposal does not have federalism implications, as defined in 
Executive Order No. 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 proposal.
    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. 98-ANE-51-AD.

    Applicability: General Electric Company (GE) GE90-90B, -85B, and 
-76B series turbofan engines, with mid fan shafts, part numbers (P/
Ns) 1767M71G01, 1767M71G02, and 1767M75G02, installed. These engines 
are installed on but not limited to Boeing 777 series aircraft.

    Note 1: This airworthiness directive (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: Required as indicated, unless accomplished 
previously.
    To prevent mid fan shaft failure, which could result in an 
uncontained engine failure and damage to the aircraft, accomplish 
the following:

Reduced Life Limits

    (a) Remove from service mid fan shafts and replace with 
serviceable parts prior to the following new, lower cyclic life 
limits:
    (1) For mid fan shafts, P/N 1767M71G01, installed on GE90-85B 
and -90B series engines, the new life limit is 4,200 cycles-since-
new (CSN).
    (2) For mid fan shafts, P/N 1767M71G02, installed on GE90-85B 
and -90B series engines, the new life limit is 4,200 CSN.
    (3) For mid fan shafts, P/N 1767M75G02, installed on GE90-76B, -
85B, and -90B series engines, the new life limit is 8,200 CSN.
    (b) This AD establishes new life limits for mid fan shafts, P/N 
1767M71G01, 1767M71G02, and 1767M75G02. Except as provided in 
paragraph (c) of this AD, no alternate life limits for these 
affected parts may be approved.

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. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

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

Ferry Flights

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

    Issued in Burlington, Massachusetts, on October 18, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-30804 Filed 11-24-99; 8:45 am]
BILLING CODE 4910-13-U