[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:

------------------------------------------------------------------------
         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]
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