AD Amdt-39-11438

[Federal Register Volume 64, Number 227 (Friday, November 26, 1999)]
[Rules and Regulations]
[Pages 66366-66368]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 99-30624]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-52-AD; Amendment 39-11438; AD 99-24-14]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-80E1A2 
Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to General Electric Company (GE) CF6-80E1A2 series 
turbofan engines. This action requires removing from service stage 2 
high pressure turbine (HPT) disks and impeller spacers prior to 
exceeding new, lower cyclic life limits and imposes a drawdown program 
for those parts that currently exceed, or will exceed, the new lower 
limits. This amendment is prompted by the results of a refined low 
cycle fatigue (LCF) analysis. The actions specified in this AD are 
intended to prevent LCF cracking and failure of stage 2 HPT disks and 
impeller spacers, which could result in an uncontained engine failure 
and damage to the aircraft.

DATES: Effective December 13, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before January 25, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 99-NE-52-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: <a href="/cdn-cgi/l/email-protection#2545451c08444b40084441464a4848404b51654344440b424a53">``<span class="__cf_email__" data-cfemail="80b9ade1eee5ade1e4e3efedede5eef4c0e6e1e1aee7eff6">[email&#160;protected]</span></a>''. Comments sent 
via the Internet must contain the docket number in the subject line.
    The service information referenced in this AD may be obtained from 
General Electric Company via Lockheed Martin Technology Services, 10525 
Chester Road, Suite C, Cincinnati, OH 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: John E. Golinski, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7135, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
received results of a refined low cycle fatigue (LCF) analysis for 
stage 2 high pressure turbine (HPT) disks and impeller spacers 
installed on General Electric Company (GE) CF6-80E1A2 series turbofan 
engines. GE has advised the FAA that the retirement lives of the CF6-
80E1A2 HPT stage 2 disk and impeller spacer identified in Chapter 5 of 
the Engine Manual need to be reduced. Updated stress analysis showed 
the operating stresses to be higher than originally predicted, 
resulting in lower calculated cyclic retirement lives for these 
components. The lower calculated cyclic lives are below the current 
retirement lives found in Chapter 5 of the Engine Manual. There have 
been no reports to date of LCF cracking or distress on these components 
attributed to parts exceeding the new reduced Chapter 5 retirement 
lives. The LCF analysis completed as part of a CF6-80E1 derivative 
model certification program showed significantly different retirement 
lives for the two engine models with similar components. GE initiated 
an investigation and assessment of the LCF analysis to understand the 
disparity and determined the updated and refined analysis resulted in a 
more complete understanding of the operating stresses for certain 
critical features for these components. This condition, if not 
corrected, could result in LCF cracking and failure of stage 2 HPT 
disks and impeller spacers, which could result in an uncontained engine 
failure and damage to the aircraft.

Service Information

    GE CF6-80E1A2 SB 72-0169, dated July 22, 1999, that describes the 
new, lower life cyclic life limits and a drawdown plan for both the 
stage 2 HPT disks and impeller spacers.

Difference Between AD and SB

    The SB, unlike this AD, includes a drawdown plan for impeller 
spacers.
    A recent reassessment of the need for a drawdown program for the 
impeller spacer occurred when a high cycle engine with the affected 
stage 2 HPT disk and impeller spacer had recently been removed from 
service due to high vibration. The assessment shows a drawdown program 
was not required for the impeller spacer.

[[Page 66367]]

    In addition, the SB includes a drawdown program for the diffuser 
vane ring which is not included in the AD.

Required Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of the same type design, this AD is 
being issued to prevent an uncontained engine failure. This AD requires 
removing from service stage 2 HPT disks, part number (P/N) 1639M50P03, 
prior to exceeding new, lower cyclic life limits, and replacing with 
serviceable parts. The AD also imposes a drawdown program for those 
parts that currently exceed, or will exceed, the new lower limits. The 
HPT impeller spacers, P/N 1473M85P02, need only to be removed and 
replaced prior to exceeding the new, lower cyclic life limit. The FAA 
has determined, based on a current fleet histogram, that a separate 
drawdown program for the HPT impeller spacer is not needed since there 
are no impeller spacers in service which exceed the new reduced cyclic 
life limit. The new life limits are based on an updated stress and life 
analysis.

Immediate Adoption

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    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 9X-NE-XX-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    This rule does not have federalism implications, as defined in 
Executive Order No. 13132, because it does 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 rule.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from 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.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

99-24-14 General Electric Company: Amendment 39-11438. Docket 99-NE-
52-AD.

    Applicability: General Electric Company (GE) CF6-80E1A2 series 
turbofan engines, with stage 2 high pressure turbine (HPT) disks, 
part number (P/N) 1639M50P03, and HPT impeller spacers, P/N 
1473M85P02, installed. These engines are installed on but not 
limited to Airbus Industrie A330 series airplanes.

    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 (d) 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 low cycle fatigue (LCF) cracking and failure of stage 
2 HPT disks and impeller spacers, which could result in an 
uncontained engine failure and damage to the aircraft, accomplish 
the following:

Stage 2 HPT Disks Drawdown Plan

    (a) Remove from service stage 2 HPT disks, P/N 1639M50P03, and 
replace with serviceable parts, as follows:

    Note 2: GE CF6-80E1A2 Service Bulletin (SB) 72-0169, dated July 
22, 1999, describes the stage 2 HPT disk drawdown plan.

    (1) For disks that have accumulated greater than or equal to 
3,800 cycles-since-new (CSN) on the effective date of this AD, 
remove within 200 cycles-in-service (CIS) after the effective date 
of this AD, but not to exceed 6,400 CSN.
    (2) For disks that have accumulated greater than or equal to 
2,500 CSN on the effective date of this AD and less than 3,800 CSN 
on the effective date of this AD, remove from service prior to 
accumulating 4,000 CSN.
    (3) For disks that have accumulated greater than or equal to 
1,900 CSN on the effective date of this AD and less than 2,500 CSN 
on the effective date of this AD, remove from service within 1,500 
CIS after the effective date of the AD.
    (4) For disks that have accumulated less than 1,900 CSN on the 
effective date of this AD, remove prior to accumulating 3,400 CSN.

New, Stage 2 HPT Disk Lower Life Limit

    (b) Except for the provisions of paragraph (d) of this AD, no 
stage 2 HPT disk, P/N 1639M50P03, may be installed with 3,400 or 
greater CSN.

[[Page 66368]]

New, Lower HPT Impeller Spacer Life Limit

    (c) Remove from service HPT impeller spacers, P/N 1473M85P02, 
prior to accumulating 5,100 CSN. Except for the provisions of 
paragraph (d) of this AD, no HPT impeller spacer, P/N 1473M85P02, 
may be installed with 5,100 or greater CSN.

    Note 3: GE CF6-80E1A2 SB 72-0169, dated July 22, 1999, describes 
an HPT impeller spacer drawdown plan that is not utilized in this 
AD.

Alternative Method of Compliance

    (d) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Ferry Flights

    (e) 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 
requirements of this AD can be accomplished.
    (f) This amendment becomes effective on December 13, 1999.

    Issued in Burlington, Massachusetts, on October 18, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-30624 Filed 11-24-99; 8:45 am]
BILLING CODE 4910-13-U