[Federal Register Volume 59, Number 220 (Wednesday, November 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-28109]
[[Page Unknown]]
[Federal Register: November 16, 1994]
BILLING CODE 4910-13-M
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-ANE-01; Amendment 39-9067; AD 94-23-05]
Airworthiness Directives; AlliedSignal Inc. TFE731-3A and -3AR
Model 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 AlliedSignal Inc. (formerly Garrett Engine Division)
TFE731-3A-200G and -3AR-200G model turbofan engines. This action
requires removing from service certain low-pressure turbine (LPT)
disks, imposing an hourly life limit on the first stage and second
stage LPT disks, performing a dimensional inspection of second stage
LPT disks at repetitive intervals, and incorporating honeycomb material
in the second stage LPT nozzle air seal. This amendment is prompted by
reports of LPT disk web separations. The actions specified in this AD
are intended to prevent LPT disk web separations, which can result in
an uncontained engine failure and damage to the aircraft.
DATES: Effective December 1, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 1, 1994.
Comments for inclusion in the Rules Docket must be received on or
before January 17, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 94-ANE-01, 12 New England
Executive Park, Burlington, MA 01803-5299.
The service information referenced in this AD may be obtained from
AlliedSignal Inc., Aviation Services Division, Data Distribution, Dept.
64-3/2102-1M, P.O. Box 29003, Phoenix, AZ 85038-9003; telephone (602)
365-2548. 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: Joseph Costa, Aerospace Engineer, Los
Angeles Aircraft Certification Office, FAA, Transport Airplane
Directorate, 3229 East Spring Street, Long Beach, CA 90806-2425;
telephone (310) 988-5246; fax (310) 988-5210.
SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA)
has received reports of two low pressure turbine (LPT) disks that
failed in the disk web area due to creep fatigue on AlliedSignal Inc.
(formerly Garrett Engine Division) Model TFE731-3A-200G turbofan
engines. Both disk failures were uncontained. A metallurgical
examination of first and second stage LPT disks found that two heat
treatment production processes created a microstructure more
susceptible to creep fatigue cracking. Both production processes
affected AlliedSignal Inc. TFE731-3 series engines' first and second
stage LPT disks.
In addition, a field inspection of LPT disks on AlliedSignal Inc.
TFE731-3 series turbofan engines revealed that excessive disk growth
occurred on AlliedSignal Inc. Model TFE731-3A-200G and TFE731-3AR-200G
engines, which are installed on Israel Aircraft Industries, Ltd. (IAI)
1125 Westwind Astra series aircraft. The FAA has determined that the
IAI Astra flight profile subjects the first and second stage LPT disks
to prolonged flight time at or near the maximum continuous inner
turbine temperatures limit. Repeated prolonged exposure to high
temperatures can cause a more rapid deterioration of the nickel-
graphite abradable material on the LPT second stage nozzle air seal
than originally anticipated during the certification process of the
engine. This deterioration results in increased seal clearance, which
contributes to disk growth. This disk growth, also known as creep,
resulting either from certain heat treatment production processes,
excessive LPT second stage nozzle air seal clearance, or the LPT
disk(s) prolonged exposure to elevated operating temperatures, if not
corrected, could result in LPT disk web separations, which can result
in an uncontained engine failure and damage to the aircraft.
The FAA has reviewed and approved the technical contents of
AlliedSignal Aerospace Alert Service Bulletin (ASB) No. TFE731-A72-
3519, Revision 3, dated May 6, 1994, that imposes an hourly life limit
on first and second stage LPT disks and describes procedures for
removal and replacement of these LPT disks; SB No. TFE731-72-3530,
Revision 1, dated October 8, 1993, that describes procedures for
installing a second stage LPT turbine nozzle that incorporates a
honeycomb air seal; and ASB No. TFE731-A72-3544, dated October 8, 1993,
and ASB No. TFE731-A72-3557, dated May 12, 1994, that describe
procedures for removal and replacement of specific serial numbered
first and second stage LPT disks. Certain requirements of this AD may
be accomplished using an earlier version of a service bulletin (SB) or
ASB than the one cited in the AD. The original version of AlliedSignal
Aerospace SB No. TFE731-72-3530 differs only by minor changes that do
not impact the technical content of the procedures, and is an
acceptable method of compliance to paragraph (c)(1) of this AD. Prior
to the effective date of this AD, replacement of LPT disks in
accordance with previous revisions of SB No. TFE731-A72-3519 is an
acceptable method of compliance to paragraph (b) or (c)(2) of this AD.
Since an unsafe condition has been identified that is likely to
exist or develop on other AlliedSignal Inc. TFE731-3A-200G series
turbofan engines of the same type design, this AD is being issued to
prevent LPT disk web separations, which can result in an uncontained
engine failure and damage to the aircraft. This AD requires removing
from service certain LPT disks, imposing an hourly life limit on first
and second stage LPT disks, performing a dimensional inspection of
second stage LPT disks at repetitive intervals, and incorporating
honeycomb material in the second stage LPT nozzle air seal. The actions
are required to be accomplished in accordance with the service
bulletins 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 94-ANE-01.'' 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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
94-23-05 AlliedSignal Inc.: Amendment 39-9067. Docket 94-ANE-01.
Applicability: AlliedSignal Inc. TFE731-3A-200G and -3AR-200G
turbofan engines installed on but not limited to Israel Aircraft
Industries, Ltd., 1125 Westwind Astra aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent low pressure turbine (LPT) disk web separations,
which can result in an uncontained engine failure and damage to the
aircraft, accomplish the following:
(a) Remove from service first and second stage LPT disks, with
Part Numbers (P/N) 3072351-( ), 3072542-( ), 3074103-1, and
3074105-1, where ( ) denotes any dash number, identified by serial
number in the Compliance Sections of AlliedSignal Aerospace Alert
Service Bulletin (ASB) No. TFE731-A72-3544, dated October 8, 1993,
and AlliedSignal Aerospace ASB No. TFE731-A72-3557, dated May 12,
1994, within 100 hours time in service (TIS) after the effective
date of this airworthiness directive (AD), in accordance with the
Accomplishment Instructions of AlliedSignal Aerospace ASB No.
TFE731-A72-3544, dated October 8, 1993, and AlliedSignal Aerospace
ASB No. TFE731-A72-3557, dated May 12, 1994, and replace with
serviceable disks.
(b) Remove first stage LPT disk, P/N 3072351-( ), where ( )
denotes any dash number, and install a serviceable first stage LPT
disk in accordance with the Accomplishment Instructions of
AlliedSignal Aerospace ASB No. TFE731-A72-3519, Revision 3, dated
May 6, 1994, as follows:
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Stage 1 LPT disk TIS since new
(TSN) Initial replacement schedule
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More than 850 hours.............. Replace within the next 50 hours TIS
after the effective date of this AD,
or at the next removal of the LPT
module, whichever occurs first.
551 to 850 hours................. Replace within the next 200 hours TIS
after the effective date of this AD,
900 hours TSN, or at the next
removal of the LPT module, whichever
occurs first.
Less than 551 hours.............. Replace prior to 750 hours TSN.
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(c) Prior to 1,500 hours TIS after the effective date of this
AD, or at the next removal of the LPT module, whichever occurs
first, accomplish the following:
(1) Replace the second stage LPT nozzle air seal, P/N 3071878-1,
in accordance with the Accomplishment Instructions of AlliedSignal
Aerospace SB No. TFE731-72-3530, Revision 1, dated October 8, 1993,
with a serviceable nozzle air seal.
(2) Replace or inspect the second stage LPT rotor assembly, P/N
3072541-( ), where ( ) denotes any dash number, and install a
serviceable assembly in accordance with the Accomplishment
Instructions of AlliedSignal Aerospace ASB No. TFE731-A72-3519,
Revision 3, dated May 6, 1994.
(d) Perform subsequent repetitive inspections and remove from
service first and second stage LPT disks, and replace with a
serviceable disk, as follows:
(1) Remove first stage LPT disks, P/N 3074103-1, prior to
accumulating 750 hours TSN, or 3,000 CSN.
(2) Remove first stage LPT disks, P/N 3073733-1, prior to
accumulating 1,500 hours TSN, or 3,000 CSN.
(3) Remove second stage LPT disks, P/N 3074105-1 prior to
accumulating 4,500 hours TSN, or 3,000 CSN.
(4) Inspect the second stage LPT rotor assembly, P/N 3074106-1,
by performing a balance rim dimensional inspection, wire gauge
check, and fluorescent penetrant inspection, in accordance with the
Engine Light Maintenance Manual, at intervals not to exceed 1,500
hours TIS since last inspection.
(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, Los Angeles Aircraft Certification
Office. The request should be forwarded through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, Los Angeles Aircraft Certification Office. NOTE:
Information concerning the existence of approved alternative methods
of compliance with this airworthiness directive, if any, may be
obtained from the Los Angeles Aircraft Certification Office.
(f) Accomplishment of the requirements of paragraph (c)(1) of
this AD in accordance with the original version of AlliedSignal
Aerospace SB No. TFE731-72-3530; or the requirements of paragraphs
(b) or (c)(2) of this AD in accordance with the original version,
Revision 1, or Revision 2 of AlliedSignal Aerospace ASB No. TFE731-
A72-3519 constitute acceptable alternative methods of compliance to
the applicable requirements of this AD.
(g) 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.
(h) The requirements of this AD shall be accomplished in
accordance with the following applicable service documents:
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Document No. Pages Revision Date
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AlliedSignal Aerospace ASB No. TFE731-A72-3544. 1-10 Original........ Oct. 8, 1993.
Total pages: 10.
AlliedSignal Aerospace SB No. TFE731-72-3530... 1-2 1............... Oct. 8, 1993.
3-4 Original........ July 2, 1993.
5 1............... Oct. 8, 1993.
6-8 Original........ July 2, 1993.
Total pages: 8.
AlliedSignal Aerospace ASB No. TFE731-A72-3519. 1-8 3............... May 6, 1994.
Total pages: 8.
AlliedSignal Aerospace ASB No. TFE731-A72-3557. 1-12 Original........ May 12, 1994.
Total pages: 12.
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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 AlliedSignal Inc., Aviation Services
Division, Data Distribution, Dept. 64-3/2102-1M, P.O. Box 29003,
Phoenix, AZ 85038-9003. 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.
(i) This amendment becomes effective on December 1, 1994.
Issued in Burlington, Massachusetts, on November 3, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-28109 Filed 11-15-94; 8:45 am]
BILLING CODE 4910-13-P