[Federal Register Volume 63, Number 8 (Tuesday, January 13, 1998)]
[Rules and Regulations]
[Pages 1901-1903]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-71]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-ANE-41-AD; Amendment 39-10231; AD 97-25-07]
RIN 2120-AA64
Airworthiness Directives; GE Aircraft Engines CT7 Series
Turboprop Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to GE Aircraft Engines (GE) CT7 series turboprop
engines, that currently requires eddy current inspection (ECI) of disk
holes of stage 1 and 2 gas generator turbine (GGT) disks for cracks,
and, if necessary, replacement with serviceable parts. This amendment
increases the initial cyclic compliance threshold while decreasing the
calendar time for performing the ECI. This amendment is prompted by
corrections to the applicable alert service bulletin (ASB) serial
number (S/N) tables. The ASB contained S/Ns which appeared in more than
one table creating confusion over which cyclic limit applied to each S/
N. The actions specified by this AD are intended to prevent a stage 1
or 2 GGT disk failure, which could result in an uncontained engine
failure and damage to the aircraft.
DATES: Effective January 28, 1998.
The incorporation by reference of GE (CT7-TP Series) Service
Bulletin 72-390, Revision 1, dated December 11, 1996, was previously
approved by the Director of the Federal Register as of April 15, 1997
(62 FR 15094, March 31, 1997).
The incorporation by reference of GE (CT7-TP Series) Alert Service
Bulletin A72-393, Revision 1, dated February 13, 1997, is approved by
the Director of the Federal Register as of January 28, 1998.
Comments for inclusion in the Rules Docket must be received on or
before March 16, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 97-ANE-41-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ad-
[email protected]''. 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
GE Aircraft Engines, 1000 Western Ave., Lynn, MA 01910; telephone (781)
594-3140, fax (781) 594-4805. This information may be examined at the
FAA, New England Region, Office of the Assistant Chief 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: Barbara Caufield, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7146, fax (781) 238-7199.
SUPPLEMENTARY INFORMATION: On February 24, 1997, the Federal Aviation
Administration (FAA) issued airworthiness directive (AD) 97-05-12,
Amendment 39-9956 (62 FR 15094, March 31, 1997), applicable to General
Electric Aircraft Engines (GE) CT7 series turboprop engines, to require
a one-time eddy current inspection (ECI) for cracks of disk holes of
stage 1 and 2 gas generator turbine (GGT) disks, and, if necessary,
replacement with serviceable parts. That action was prompted by a
report of a GE CT7 series turboprop engine, installed on a SAAB-SCANIA
SF340 aircraft, that experienced an uncontained stage 2 GGT failure
during takeoff. The investigation revealed that the failure was caused
by a crack in a disk cooling hole. The most likely cause of the
cracking was machining damage to the disk cooling hole during
manufacturing. That condition, if not corrected, could result in a
stage 1 or 2 GGT disk failure, which could result in an uncontained
engine failure and damage to the aircraft.
This amendment is prompted by a revision to the applicable alert
service bulletin (ASB) that provides corrections to the serial number
(S/N) tables. The ASB contained S/Ns which appeared in more than one
table creating confusion over which cyclic limit applied to each S/N.
This amendment supersedes the existing AD and increases the initial
cyclic compliance threshold while decreasing the calendar time for
performing the ECI. The compliance times have been adjusted to ensure
that no part exceeds the cyclic limits nor the compliance end date as
calculated by GE's risk analysis.
The FAA has reviewed and approved the technical contents of GE
(CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that
lists by S/N affected stage 1 and 2 GGT disks, and GE (CT7-TP Series)
Service Bulletin 72-390, Revision 1, dated December 11, 1996, that
describes procedures for ECI of disk holes for cracks.
Since an unsafe condition has been identified that is likely to
exist or develop on other engines of this same type design, this AD
supersedes AD 97-05-12 to increase the initial cyclic compliance
threshold while decreasing the calendar time for performing the ECI.
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
[[Page 1902]]
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 97-ANE-41-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 removing Amendment 39-9956, (62 FR
15094, March 31, 1997), and by adding a new airworthiness directive,
Amendment 39-10231, to read as follows:
97-25-07 GE Aircraft Engines: Amendment 39-10231. Docket 97-ANE-41-
AD. Supersedes AD 97-05-12, Amendment 39-9956.
Applicability: GE Aircraft Engines (GE) Models CT7-5A2, -7A, -
9B, -9C turboprop engines, installed on but not limited to
Construcciones Aeronauticas, SA (CASA) CN-235 series and SAAB-SCANIA
SF340 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 (l) 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 a stage 1 or 2 gas generator turbine (GGT) disk
failure, which could result in an uncontained engine failure and
damage to the aircraft, accomplish the following:
(a) For all stage 1 GGT disks, Part Number (P/N) 6064T06P01,
identified in Table 1 of GE (CT7-TP Series) Alert Service Bulletin
(ASB) A72-393, Revision 1, dated February 13, 1997, that have
accumulated 8,500 or more cycles since new (CSN) on the effective
date of this AD, perform a one time eddy current inspection (ECI)
for cracks in accordance with the Accomplishment Instructions of GE
(CT7-TP Series) Service Bulletin (SB) 72-390, Revision 1, dated
December 11, 1996, at the next GGT module removal, or not to exceed
3 months after the effective date of this AD, whichever occurs
first.
(b) For all stage 1 GGT disks, P/N 6064T06P01, identified in
Table 1 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated less than 8,500 CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, but not to exceed 9,000 CSN.
(c) For all stage 1 GGT disks, P/N 6064T06P01, identified in
Table 2 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated 11,500 or more CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, or not to exceed 3 months after the effective
date of this AD, whichever occurs first.
(d) For all stage 1 GGT disks, P/N 6064T06P01, identified in
Table 2 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated less than 11,500 CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, but not to exceed 12,000 CSN.
(e) For all stage 2 GGT disks, P/N 6064T12P01, identified in
Table 3 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated 8,500 or more CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, or not to exceed 3 months after the effective
date of this AD, whichever occurs first.
(f) For all stage 2 GGT disks, P/N 6064T12P01, identified in
Table 3 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated less than 8,500 CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
[[Page 1903]]
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, but not to exceed 9,000 CSN.
(g) For all stage 2 GGT disks, P/N 6064T12P01, identified in
Table 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated 11,500 or more CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, or not to exceed 3 months after the effective
date of this AD, whichever occurs first.
(h) For all stage 2 GGT disks, P/N 6064T12P01, identified in
Table 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated
February 13, 1997, that have accumulated less than 11,500 CSN on the
effective date of this AD, perform a one time ECI for cracks in
accordance with the Accomplishment Instructions of GE (CT7-TP
Series) SB 72-390, Revision 1, dated December 11, 1996, at the next
GGT module removal, but not to exceed 12,000 CSN.
(i) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2
GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of
GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997,
that have accumulated 8,500 or more CSN on the effective date of
this AD, perform a one time ECI for cracks in accordance with the
Accomplishment Instructions of GE (CT7-TP Series) SB 72-390,
Revision 1, dated December 11, 1996, at the next GGT module removal,
or not to exceed 3 months after the effective date of this AD,
whichever occurs first.
(j) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2
GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of
GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997,
that have accumulated less than 8,500 CSN on the effective date of
this AD, perform a one time ECI for cracks in accordance with the
Accomplishment Instructions of GE (CT7-TP Series) SB 72-390,
Revision 1, dated December 11, 1996, at the next GGT module removal,
but not to exceed 9,000 CSN.
(k) Prior to further flight, remove from service cracked disks,
and replace with serviceable parts.
(l) 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.
(m) 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 requirements of this AD can be accomplished.
(n) The actions required by this AD shall be done in accordance
with the following GE (CT7-TP Series) service documents:
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Document No. Pages Revision Date
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ASB A72-393.................. 1-16 1 Feb. 13, 1997.
Total pages: 16.
SB 72-390.................... 1-6 1 Dec. 11, 1996.
Total pages: 6.
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(o) The incorporation by reference of GE (CT7-TP Series) SB 72-
390, dated December 11, 1996, was previously approved by the
Director of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51 as of April 15, 1997 (62 FR 15094, March 31,
1997).
(p) The incorporation by reference of GE (CT7-TP Series ) ASB
A72-393, Revision 1, dated February 13, 1997, is approved by the
Director of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51 as of January 28, 1998.
(q) Copies of the service documents may be obtained from GE
Aircraft Engines, 1000 Western Ave., Lynn, MA 01910; telephone (781)
594-3140, fax (781) 594-4805. Copies may be inspected at the FAA,
New England Region, Office of the Assistant Chief 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.
(r) This amendment becomes effective on January 28, 1998.
Issued in Burlington, Massachusetts, on December 23, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 98-71 Filed 1-12-98; 8:45 am]
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