[Federal Register Volume 61, Number 41 (Thursday, February 29, 1996)]
[Rules and Regulations]
[Pages 7690-7692]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-4243]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-ANE-54; Amendment 39-9512; AD 96-04-01]
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 turbofan engines, that currently requires eddy
current inspection of certain fan rotor disks for cracks, and
replacement, if necessary, with serviceable parts. This amendment
requires reinspection of 33 additional fan rotor disks, beyond the
quantity of reinspections required by AD 93-25-16. This amendment is
prompted by discrepancies in several magnetic tape records discovered
as a result of recent improvements in the inspection tape review
process. The actions specified by this AD are intended to prevent an
uncontained failure of the fan rotor disk 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 March 15, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of March 15, 1996.
Comments for inclusion in the Rules Docket must be received on or
before April 29, 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-54, 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 64-03/2101-201,
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 December 21, 1993, the Federal Aviation
Administration (FAA) issued airworthiness directive (AD) 93-25-16,
Amendment 39-8780 (59 FR 4, January 3, 1994), applicable to
AlliedSignal Inc. (formerly Garrett Engine Division) TFE731-2, -3, and
-3R series turbofan engines. That AD requires eddy current inspection
of certain fan rotor disks for cracks, and replacement, if necessary,
of these fan rotor disks. That action was prompted by reports of an
uncontained failure of a fan rotor disk on an Allied Signal Inc. Model
TFE731-3 turbofan engine. The FAA investigation determined that a
fatigue crack originated in the aft acute corner of the dovetail slot.
The fan rotor disk had accumulated a total of 5,291 cycles in service
(CIS) at the time of the failure, and had been eddy current inspected
in 1990 when the disk had accumulated 4,055 CIS. The fan rotor disk
displayed evidence of broaching grooves produced during the manufacture
of the blade dovetail slots. These machining grooves may have
contributed to the fan rotor disk failure. From a metallurgical
analysis, the FAA determined that the failed fan rotor disk had
dovetail cracks which were not detected at the time of the eddy current
inspection. A review of the eddy current inspection process used to
inspect this fan rotor disk and all fan rotor disks inspected prior to
May 1991 determined that the inspection process was not acceptable.
Those fan rotor disk cracks, if not corrected, could result in an
uncontained failure of the fan rotor disk 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.
After 1991, the eddy current inspection process required magnetic
tape records (henceforth referred to as tapes) of the eddy current
inspection
[[Page 7691]]
results for the fan rotor disk dovetail slots. These tapes can be
reviewed at any time following the initial inspection without
inconveniencing the operator. Since the issuance of that AD, through
recent improvements in the inspection tape review process, and
continued review of the tapes, the FAA has identified several tape
records as having discrepancies. A discrepancy does not always indicate
that a crack exists. This superseding AD requires a re-inspection of 33
additional fan rotor disks, beyond the quantity of reinspections
required by AD 93-25-16, to ensure that cracked fan rotor disks are
removed from service. To date, eddy current inspections have detected
fatigue cracks in the dovetail slots in approximately 176 (or 4%)
TFE731-2, -2A, -3, and -3R fan rotor disks, and those fan rotor disks
have been removed from service.
The FAA has reviewed and approved the technical contents of
AlliedSignal Alert Service Bulletin (ASB) No. TFE731-A72-3578, dated
May 31, 1995, that describes procedures for an improved, more
definitive eddy current inspection for fan rotor disk dovetail slot
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 93-25-16 to require reinspection of 33 additional fan
rotor disks, beyond the quantity of reinspections required by AD 93-25-
16, to ensure that cracked fan rotor disks are removed from service.
This action is required to be accomplished in accordance with the ASB
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 95- ANE-54.'' 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 USC 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing Amendment 39-8780, (59 FR
4, January 3, 1994), and by adding a new airworthiness directive,
Amendment 39-9512, to read as follows:
96-04-01 AlliedSignal Inc.: Amendment 39-9512. Docket 95- ANE-54.
Supersedes AD 93-25-16, Amendment 39-8780.
Applicability: AlliedSignal Inc. (formerly Garrett Engine
Division) TFE731-2, -2A, -3, -3R series turbofan engines with fan
rotor disks, part numbers (P/N's) 3072162-1 through -4, 3073436-1
through -4, 3073539-2, and 3074529-2, installed on, but not limited
to: Avions Marcel Dassault Falcon 10, 50, 100 series; Learjet 31,
35, 36 series; Lockheed-Georgia 1329-23, -25 series; Israel Aircraft
Industries 1124 series; Raytheon British Aerospace HS125 series; and
Sabreliner NA-265-65 aircraft.
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 (e) 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 an uncontained failure of the fan rotor disk 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) No further action is required for fan rotor disks previously
eddy current inspected in accordance with the requirements of AD 92-
26-09 and AD 93-25-16.
(b) Remove prior to further flight fan rotor disk, P/N 3073539-2
or 3072162-2, with Serial Number (S/N) 8-18040-6300, in accordance
with Allied-Signal Inc. Alert Service Bulletin (ASB) No. TFE731-A72-
3504, dated November 25, 1992, or AlliedSignal Inc. ASB No. TFE731-
A72-
[[Page 7692]]
3504, Revision 1, dated July 2, 1993, and replace with a serviceable
fan rotor disk.
(c) Incorporate new eddy current inspection procedures in
accordance with ASB No. TFE731-A72-3578, dated May 31, 1995, within
30 days after the effective date of this AD. Fan rotor disks
requiring eddy current inspection, prior to the incorporation of the
new eddy current procedure previously mentioned, may be inspected in
accordance with AlliedSignal Inc. ASB No TFE731-A72-3504 dated
November 25, 1992, or TFE731-A72-3504, Revision 1, dated July 2,
1993.
(d) Eddy current inspect fan rotor disks, P/N 3072162-1 through
-4, 3073436-1 through -4, 3073539-2, and 3074529-2, in accordance
with the Accomplishment Instructions of AlliedSignal Inc. ASB No.
TFE731-A72-3578, dated May 31, 1995, and if necessary, replace with
a serviceable disk, as follows:
(1) For fan rotor disks listed by S/N in Table 2 of Allied-
Signal Inc. ASB No. TFE731-A72-3504, dated November 25, 1992, or
AlliedSignal Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2,
1993, inspect, and if necessary, replace with a serviceable fan
rotor disk within 50 cycles in service (CIS) after April 9, 1993
(effective date of AD 92-26-09).
(2) For the 10 added fan rotor disks listed by S/N in Table 3 of
AlliedSignal Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2,
1993, with 5,000 or more CIS since new on January 18, 1994
(effective date of AD 93-25-16), inspect, and if necessary, replace
with a serviceable fan rotor disk, within the next 50 CIS after
January 18, 1994 (effective date of AD 93-25-16).
(3) For fan rotor disks listed by S/N in Table 3 of AlliedSignal
Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2, 1993, other
than the 10 added fan rotor disks, with 5,000 or more CIS since new
on April 9, 1993, (effective date of AD 92-26-09), inspect, and if
necessary, replace with a serviceable fan rotor disk, within the
next 50 CIS after April 9, 1993 (effective date of AD 92-26-09).
(4) For the 10 added fan rotor disks listed by S/N in Table 3 of
AlliedSignal Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2,
1993, with less than 5,000 CIS since new on January 18, 1994,
(effective date of AD 93-25-16), inspect, and if necessary, replace
with a serviceable fan rotor disk within the next 100 CIS after
January 18, 1994, (effective date of AD 93-25-16) or prior to
accumulating 5,050 CIS since new, whichever occurs first.
(5) For fan rotor disks listed by S/N in Table 3 of AlliedSignal
Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2, 1993, other
than the 10 added fan rotor disks, with less than 5,000 CIS since
new on April 9, 1993 (effective date of AD 92-26-09), inspect, and
if necessary, replace with a serviceable fan rotor disk, within the
next 100 CIS after April 9, 1993 (effective date of AD 92-26-09), or
prior to accumulating 5,050 CIS since new, whichever occurs first.
(6) For fan rotor disks listed by S/N in Table 4 of AlliedSignal
Inc. ASB No. TFE731-A72-3504, Revision 1, dated July 2, 1993,
inspect, and if necessary, replace with a serviceable fan rotor
disk, within the next 100 CIS after January 18, 1994, (effective
date of AD 93-25-16).
(7) For fan rotor disks listed by S/N in Table 1 of AlliedSignal
Inc. ASB No. TFE731-A72-3578, dated May 31, 1995, inspect, and if
necessary, replace with a serviceable disk, within 50 CIS after the
effective date of this AD.
(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) 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.
(g) 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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AlliedSignal Inc. ASB No. 1-12 Original...... May 31, 1995.
TFE731-A72-3578.
Total pages: 12.
Allied-Signal Inc. ASB No. 1-24 Original...... November 25,
TFE731-A72-3504. 1992.
Total pages: 24.
Allied-Signal Inc. ASB No. 1-28 Revision 1.... July 2, 1993.
TFE731-A72-3504.
Total pages: 28.
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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 Aerospace, Attn: Data
Distribution, M/S 64-03/2101-201, 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.
(h) This amendment becomes effective on March 15, 1996.
Issued in Burlington, Massachusetts, on February 2, 1996.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 96-4243 Filed 2-28-96; 8:45 am]
BILLING CODE 4910-13-P
