[Federal Register Volume 63, Number 134 (Tuesday, July 14, 1998)]
[Rules and Regulations]
[Pages 37761-37763]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18647]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-17-AD; Amendment 39-10654; AD 98-15-03]
RIN 2120-AA64
Airworthiness Directives; General Electric Company GE90 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) GE90 series turbofan
engines. This action requires initial and repetitive eddy current
inspections (ECI) for cracks in the high pressure compressor (HPC)
stage 2-6 spool, and, if necessary, replacement with serviceable parts.
This amendment is prompted by reports of cracks in the stage 3-4 and
stage 4-5 interstage seal teeth and spacer arms. The actions specified
in this AD are intended to identify cracks in the HPC stage 2-6 spool,
which could result in an uncontained engine failure and damage to the
aircraft.
DATES: Effective July 29, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of July 29, 1998.
Comments for inclusion in the Rules Docket must be received on or
before September 14, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 98-ANE-17-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``engineprop@faa.dot.gov''. 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 Technical Services, Attention: Leader for
distribution/ microfilm, 10525 Chester Road, Cincinnati, OH 45215;
telephone (513) 672-8400 Ext. 130, 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; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Ian Dargin, Aerospace Engineer, Engine
Certification Office, FAA, Engine and Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7178, fax (781) 238-7199.
SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA)
has received reports of cracked high pressure compressor (HPC) stage 2-
6 spools installed on General Electric Company (GE) GE90-76B/ -77B/ -
85B/ -90B/ -92B series turbofan engines. There have been 10 HPC spools
found with cracks. The investigation into the cause of the cracking is
ongoing; however, the FAA has determined that the HPC stage 2-6 spool
may develop cracks in the stage 3-4 and stage 4-5 interstage seal teeth
that could propagate into the stage 3-4 and stage 4-5 spacer arms, aft
of the seal teeth. This AD requires inspection of the spacer arm aft of
the seal teeth and also includes an inspection requirement for the
spacer arm forward of the seal teeth that provides additional data to
support the investigation and mitigates the risk of an HPC stage 2-6
spool failure from a crack propagating into the spacer arm forward of
the seal teeth. The FAA has determined the most likely cause of crack
initiation is due to areas of heat affected zone in the seal teeth that
is the result of excessive heat generated when
[[Page 37762]]
the rotating seal teeth rub into the static honeycomb material. This
condition, if not corrected, could result in HPC stage 2-6 spool
cracking, which could result in an uncontained engine failure and
damage to the aircraft.
The FAA has reviewed and approved the technical contents of GE
Alert Service Bulletin (ASB) No. 72-A357, Revision 2, dated April 21,
1998, that describes procedures for on-wing eddy current inspection
(ECI) for cracks in the HPC stage 2-6 spool spacer arm forward and aft
of the stage 3-4 and stage 4-5 interstage seal teeth, and GE Service
Bulletin (SB) No. 72-352, Revision 2, dated March 31, 1998, that
describes procedures for ECI of stage 3-4 and stage 4-5 interstage seal
teeth.
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 identify cracks in the HPC stage 2-6 spool, which could
result in an uncontained engine failure and damage to the aircraft.
This AD requires:
(1) Initial and repetitive on-wing ECI for cracks in the HPC stage
2-6 spool spacer arms forward and aft of the stage 3-4 and stage 4-5
interstage seal teeth, and, if necessary, replacement with a
serviceable engine.
(2) A shop level ECI for cracks in the HPC stage 2-6 spool stage 3-
4 and stage 4-5 interstage seal teeth, and, if necessary, replacement
with serviceable parts.
Since this investigation is ongoing, further rulemaking may be
necessary. The actions are required to be accomplished in accordance
with the service documents described previously.
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
in triplicate 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 98-ANE-17-AD.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
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, Incorporation by
reference, 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:
98-15-03 General Electric Company: Amendment 39-10654. Docket 98-
ANE-17-AD.
Applicability: General Electric Company (GE) GE90-76B/ -77B/ -
85B/ -90B/ -92B series turbofan engines, with high pressure
compressor (HPC) stage 2-6 spools, Part Numbers 350-005-761-0, 350-
005-765-0, 350-005-769-0, 350-005-770-0, or 350-005-771-0,
installed. These engines are installed on but not limited to Boeing
777 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 (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 identify cracks in the high pressure compressor (HPC) stage
2-6 spool, which could result in an uncontained engine failure and
damage to the aircraft, accomplish the following:
(a) Perform initial and repetitive on-wing eddy current
inspections (ECI) for cracks in HPC stage 2-6 spool spacer arms in
accordance with GE Alert Service Bulletin (ASB) No. 72-A357,
Revision 2, dated April 21, 1998.
(1) Perform inspections of the spacer arm forward and aft of the
stage 3-4 and 4-5 seal teeth as follows:
(i) Perform the initial inspection prior to exceeding 500 cycles
since new (CSN).
(ii) Thereafter, inspect at intervals not to exceed 250 cycles
in service (CIS) since last inspection.
(2) Remove the engine from service if the ECI reveals a spool
with a crack indication and replace with a serviceable engine prior
to further flight.
(b) Perform initial and repetitive ECI for cracks in the HPC 2-6
spool stage 3-4 and
[[Page 37763]]
stage 4-5 interstage seal teeth during each shop visit as defined in
paragraph (c) of this AD, and if necessary, replace with serviceable
parts prior to returning the engine to revenue service, in
accordance with GE Service Bulletin (SB) No. 72-352, Revision 2,
dated March 31, 1998.
(c) For the purpose of this AD, an engine shop visit is defined
as any time an engine has maintenance performed that involves
separation of a major engine flange (such as removal of an LPT
module or HPC ``top case'').
(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.
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.
(e) Special flight permits may be issued in accordance with
sections 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.
(f) The actions required by this AD shall be done in accordance
with the following GE service documents:
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Document Number Pages Revision Date
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SB No. 72-352................................ 1-32 2 March 31, 1998.
Total pages: 32
ASB No. 72-A357.............................. 1-30 2 April 21, 1998.
Total pages: 30
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This incorporation by reference was approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part
51. Copies may be obtained from General Electric Technical Services,
Attention: Leader for distribution/microfilm, 10525 Chester Road,
Cincinnati, OH 45215; telephone (513) 672-8400 Ext. 130, fax (513)
672-8422. Copies may be inspected at the FAA, New England Region,
Office of the Regional Counsel, 12 New England Executive Park,
Burlington, MA; or at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on July 29, 1998.
Issued in Burlington, Massachusetts, on July 6, 1998.
Jay J. Pardee,
Manager, Engine and Propeller Directorate,
Aircraft Certification Service.
[FR Doc. 98-18647 Filed 7-10-98; 9:29 a.m.]
BILLING CODE 4910-13-P
