[Federal Register Volume 61, Number 53 (Monday, March 18, 1996)]
[Rules and Regulations]
[Pages 10881-10884]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-6450]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-ANE-53; Amendment 39-9529; AD 96-05-03]
Airworthiness Directives; AlliedSignal Inc. TFE731 Series
Turbofan 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 AlliedSignal Inc. (formerly Garrett Engine
Division) TFE731 Series
[[Page 10882]]
Turbofan Engines, that currently requires inspection of fan rotor disks
within certain schedules. This amendment requires initial and
repetitive eddy current inspections using an improved, more definitive
procedure for detecting fan rotor disk dovetail slot cracks. Also, this
amendment adds additional engine models and fan rotor disk part numbers
and disallows fluorescent penetrant inspection (FPI) as an alternative
inspection method for detecting fan rotor disk dovetail slot cracks.
This amendment is prompted after additional analyses revealed that
stress levels in the fan rotor disk dovetail slots for the applicable
engine models are higher than initially calculated. The actions
specified by this AD are intended to prevent uncontained failure of fan
rotor disks due to fatigue cracking in the dovetail slots, which can
result in inflight engine shutdowns, severe secondary damage, and fan
rotor assembly separation from the engine.
DATES: Effective April 2, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of April 2, 1996.
Comments for inclusion in the Rules Docket must be received on or
before May 17, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 95-ANE-53, 12 New England
Executive Park, Burlington, MA 01803-5299.
The service information referenced in this AD may be obtained from
AlliedSignal Aerospace, Attn: Data Distribution, M/S 64-3/2101-201,
P.O. Box 29003, Phoenix, AZ 85038-9003; telephone (602) 365-2493, fax
(602) 365-5577. This information may be examined at the FAA, New
England Region, Office of the Assistant Chief Counsel, 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, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone
(310) 627-5246; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION: On July 15, 1993, the Federal Aviation
Administration (FAA) issued airworthiness directive (AD) 91-08-13,
Amendment 39-8611 (58 FR 40732, July 30, 1993), to require inspection
of fan rotor disks within certain schedules installed on AlliedSignal
Inc. (formerly Garrett Engine Division) Model TFE731-2, -3, and -3R
turbofan engines. That action was prompted by a report of an in-service
uncontained failure of the first stage fan rotor disk in which a
segment of the fan rotor disk rim and five fan blades departed the
engine. Metallurgical examination of the fractured fan rotor disk
determined that a fatigue crack had initiated in the area of the aft
acute corner of one of the dovetail slots in the fan rotor disk.
Failure of this fan rotor disk occurred at 3,300 cycles which was less
than the then FAA-approved life limit of 4,100 cycles. That condition,
if not corrected, could result in uncontained failure of fan rotor
disks due to fatigue cracking in the dovetail slots, which can result
in inflight engine shutdowns, severe secondary damage, and fan rotor
assembly separation from the engine.
Since the issuance of that AD, the FAA has determined from
additional analyses that stress levels in the fan rotor disk dovetail
slots for the applicable engine models are higher than initially
calculated. Also, additional TFE731 series engine models have similar
stress levels. From fan rotor disk dovetail slot eddy-current
inspection data, the FAA has determined that 8 (or 1%) of those TFE731-
3A, -3AR, -3B, -3BR, -3C, -3CR, and -4R fan rotor disks inspected
exhibited fatigue cracking and were removed from service. Moreover,
similar eddy-current inspection data from the TFE731-2, -3, and -4
series engines has indicated that crack detectability from a one-time
eddy-current inspection is between 80-90 percent, which is not as high
as previously evaluated. Therefore, the FAA has determined that initial
and repetitive eddy-current inspections must be performed using an
improved, more definitive procedure. Furthermore, the FAA has
determined that fluorescent penetrant inspection (FPI) is not adequate
to detect fan rotor disk dovetail slot cracks. Accordingly, this AD
disallows FPI as an alternative inspection method for detecting fan
rotor disk dovetail slot cracks.
The FAA has reviewed and approved the technical contents of
AlliedSignal Inc. Alert Service Bulletin (ASB) No. TFE731-A72-3432,
dated April 11, 1991; AlliedSignal Inc. ASB No. TFE731-A72-3432,
Revision 1, dated April 30, 1991; AlliedSignal Inc. ASB No. TFE731-A72-
3432, Revision 2, dated June 3, 1991; AlliedSignal Inc. ASB No. TFE731-
A72-3432, Revision 3, dated October 17, 1991; AlliedSignal Inc. ASB No.
TFE731-A72-3432, Revision 4, dated August 6, 1993; AlliedSignal Inc.
ASB No. TFE731-A72-3432, Revision 5, dated May 31, 1995, and
AlliedSignal Inc. ASB No. TFE731-A72-3445, Revision 2, dated May 31,
1995. These ASB's describe procedures for initial and repetitive eddy
current inspections of fan rotor disks 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 91-08-13 to require initial and repetitive eddy current
inspections using an improved, more definitive procedure for detecting
fan rotor disk dovetail slot cracks. In addition, this amendment adds:
the TFE731-2A, -3A, -3AR, -3B, -3BR, -3C, -3CR, -3D, -3DR, and -4R
engines models to the Applicability section; adds fan rotor disk part
numbers 3072161-5, 3073436-5, 3072816-1, -2, and -3, 3073539-(All), and
3074529-(All), where (All) denotes any dash number, to the Compliance
section; and disallows FPI as an alternative inspection method for
detecting fan rotor disk dovetail slot cracks. These actions are
required to be accomplished in accordance with the ASB's 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
[[Page 10883]]
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 95-ANE-53.'' 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 39-8611, (58 FR
40732, July 30, 1993), and by adding a new airworthiness directive,
Amendment 39-9529, to read as follows:
96-05-03 AlliedSignal Inc.: Amendment 39-9529. Docket 95-ANE-53.
Supersedes AD 91-08-13, Amendment 39-8611.
Applicability: AlliedSignal Inc. (formerly Garrett Engine
Division) TFE731-2, -2A, -3, -3A, -3AR, -3B, -3BR, -3C, -3CR, -3D, -
3DR, -3R, and -4R series turbofan engines with fan rotor disk part
numbers (P/N's) 3072162-1 through -5, 3072816-1, -2, and -3,
3073436-1 through -5, 3073539-(All), and 3074529-(All), where (All)
denotes any dash number, installed on but not limited to the
following aircraft: Avions Marcel Dassault Falcon 10, 50, 100
series; Learjet 31, 35, 36, and 55 series; Lockheed-Georgia 1329-23
and -25 series; Israel Aircraft Industries 1124 and 1125 series;
Cessna 650, Citations III, VI, and VII; Raytheon British Aerospace
HS-125 series; and Sabreliner NA-265-65.
Note: 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 use the
authority provided in paragraph (b) to request approval from the
Federal Aviation Administration (FAA). This approval may address
either no action, if the current configuration eliminates the unsafe
condition, or different actions necessary to address the unsafe
condition described in this AD. Such a request should include an
assessment of the effect of the changed configuration on the unsafe
condition addressed by this AD. In no case does the presence of any
modification, alteration, or repair remove any engine from the
applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent uncontained failure of fan rotor disks due to fatigue
cracking in the dovetail slots, which can result in inflight engine
shutdowns, severe secondary damage, and fan rotor assembly
separation from the engine, accomplish the following:
(a) Remove and conduct initial and repetitive eddy current
inspections for cracks on affected fan rotor disks, and, if
necessary, replace cracked fan rotor disks with a serviceable disk,
as follows:
(1) Fan rotor disks whose dovetail slots have never been eddy-
current inspected must comply with the initial inspection described
in paragraphs (3), (4), (5), or (6) of this AD, as applicable.
Additionally, all fan rotor disks whose dovetail slots have been
previously eddy-current inspected must comply with the repetitive
inspections in accordance with paragraphs (7), (8), or (9) of this
AD, as applicable.
(2) For paragraphs (3) and (7) of this AD, incorporate new eddy
current inspection procedures in accordance with the Accomplishment
Instructions (AI) of AlliedSignal Inc. Alert Service Bulletin (ASB)
No. TFE731-A72-3432, Revision 5, dated May 31, 1995, within 30 days
after the effective date of this AD. Those fan rotor disks requiring
eddy current inspection, prior to the incorporation of the new eddy
current procedure, may be inspected in accordance with the AI 's of
Allied-Signal Inc. ASB No. TFE731-A72-3432, dated April 11, 1991;
Allied-Signal Inc. ASB No. TFE731-A72-3432, Revision 1, dated April
30, 1991; Allied-Signal Inc. ASB No. TFE731-A72-3432, Revision 2,
dated June 3, 1991; Allied-Signal Inc. ASB No. TFE731-A72-3432,
Revision 3, dated October 17, 1991; or AlliedSignal Inc. ASB No.
TFE731-A72-3432, Revision 4, dated August 6, 1993.
(3) For engines with Part Number (P/N) 3072162-1 through -4, and
P/N 3073436-1 through -4, inspect in accordance with the AI of
AlliedSignal Inc. ASB No. TFE731-A72-3432, Revision 5, dated May 31,
1995, as required by Schedule A, using fan rotor disks cycles since
new (CSN) on August 16, 1993 (effective date of AD 91-08-13).
Schedule A
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Fan rotor disk (CSN) Initial inspection schedule
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Greater than 2,800.................... Within the next 50 cycles in
service (CIS) after August 16,
1993 (effective date of AD 91-
08-13).
2,301 through 2,800................... Within the next 100 CIS after
August 16, 1993 (effective date
of AD 91-08-13), or prior to
2,850 CSN, whichever occurs
first.
1,601 through 2,300................... Within the next 200 CIS after
August 16, 1993 (effective date
of AD 91-08-13) or prior to
2,400 CSN, whichever occurs
first.
1,600 or less......................... Prior to accumulating 1,800 CSN.
------------------------------------------------------------------------
(4) For engines with P/N's 3072162-5, 3073436-5, 3073539-1, and
3074529-1, inspect in accordance with the AI of AlliedSignal Inc.
ASB No. TFE731-A72-3432, Revision 5, dated May 31, 1995, as required
by Schedule B, using fan rotor disk CSN on the effective date of
this AD.
Schedule B
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Fan rotor disk CSN Initial inspection schedule
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Greater than 1,600.................... Within the next 200 CIS after
the effective date of this AD.
1,600 or less......................... Prior to accumulating 1,800 CSN.
------------------------------------------------------------------------
(5) For engines with P/N's 3072816-1 and -2, inspect in accordance
with the AI of AlliedSignal Inc. ASB No. TFE731-A72-3445, Revision 2,
dated
[[Page 10884]]
May 31, 1995, as required by Schedule C, using fan rotor disk CSN on
the effective date of this AD.
Schedule C
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Fan rotor disk CSN Initial inspection schedule
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Greater than 2,800.................... Within 50 CIS after the
effective date of this AD.
2,301 to 2,800........................ Within 100 CIS after the
effective date of this AD, or
prior to 2,850 CSN, whichever
occurs first.
2,300 or less......................... Prior to accumulating 2,400 CSN.
------------------------------------------------------------------------
(6) For engines with P/N 3072816-3, inspect in accordance with
the AI of AlliedSignal Inc. ASB No. TFE731-A72-3445, Revision 2,
dated May 31, 1995, as required by Schedule D, using fan rotor disk
CSN on the effective date of this AD.
Schedule D
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Fan rotor disk CSN Initial inspection schedule
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Greater than 2,200.................... Within 200 CIS after the
effective date of this AD.
2,200 or less......................... Prior to accumulating 2,400 CSN.
------------------------------------------------------------------------
(7) For engines with P/N 3072162-1, -2, -3, and -4, P/N 3073436-
1, -2, -3, and -4, thereafter inspect in accordance with the AI of
AlliedSignal Inc. ASB No. TFE731-A72-3432, Revision 5, dated May 31,
1995, at every Major Periodic Inspection (MPI), as defined in the
applicable engine maintenance manual, or prior to accumulating 1,300
CIS since last eddy current inspection, whichever occurs first.
(8) For engines with P/N's 3072162-5, 3073436-5, 3073539-(All),
and 3074529-(All), where (All) denotes any dash number, thereafter
inspect in accordance with the AI of AlliedSignal Inc. ASB No.
TFE731-A72-3432, Revision 5, dated May 31, 1995, as required by
Schedule E.
Schedule E
------------------------------------------------------------------------
Fan rotor disk CIS since previous eddy
current inspection Repetitive inspection schedule
------------------------------------------------------------------------
Greater than 1,100.................... Within 200 CIS after the
effective date of this AD.
1,100 or less......................... Every engine MPI or prior to
accumulating 1,300 CIS since
last eddy current inspection,
whichever occurs first.
------------------------------------------------------------------------
(9) For engines with P/N 3072816-1, -2, and -3, thereafter
inspect in accordance with the AI of AlliedSignal Inc. ASB No.
TFE731-A72-3445, Revision 2, dated May 31, 1995, as required by
Schedule F.
Schedule F
------------------------------------------------------------------------
Fan rotor disk CIS since previous eddy
current inspection Repetitive inspection schedule
------------------------------------------------------------------------
Greater than 1,100.................... Within 200 CIS after the
effective date of this AD.
1,100 or less......................... Every engine MPI or prior to
accumulating 1,300 CIS since
last eddy current inspection,
whichever occurs first.
------------------------------------------------------------------------
(b) 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.
(c) 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.
(d) The actions required by this AD shall be done in accordance
with the following service documents:
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Document No. Pages Revision Date
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Allied-Signal Inc., ASB No. TFE731- 1-16 Original................ April 11, 1991.
A72-3432.
Total pages: 16.
Allied-Signal Inc., ASB No. TFE731- 1-22 1....................... April 30, 1991.
A72-3432.
Total pages: 22.
Allied-Signal Inc., ASB No. TFE731- 1-20 2....................... June 3, 1991.
A72-3432.
Total pages: 20.
Allied-Signal Inc., ASB No. TFE731- 1-22 3....................... October 17, 1991.
A72-3432.
Total pages: 22.
Allied-Signal Inc., ASB No. TFE731- 1-16 4....................... August 6, 1993.
A72-3432.
Total pages: 16.
Allied-Signal Inc., ASB No. TFE731- 1-14 5....................... May 31, 1995.
A72-3432.
Total Pages: 14.
Allied-Signal Inc., ASB No. TFE731- 1-14 2....................... May 31, 1995.
A72-3445.
Total Pages: 14.
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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 Allied-Signal Aerospace, Attn:
Data Distribution, M/S 64-3/2101-201, P.O. Box 29003, Phoenix, AZ
85038-9003; telephone (602) 365-2493, fax (602) 365-5577. 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.
(e) This amendment becomes effective on April 2, 1996.
Issued in Burlington, Massachusetts, on February 26, 1996.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 96-6450 Filed 3-15-96; 8:45 am]
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