[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                               
------------------------------------------------------------------------
         Fan rotor disk (CSN)              Initial inspection schedule  
------------------------------------------------------------------------
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                               
------------------------------------------------------------------------
          Fan rotor disk CSN               Initial inspection schedule  
------------------------------------------------------------------------
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                               
------------------------------------------------------------------------
          Fan rotor disk CSN               Initial inspection schedule  
------------------------------------------------------------------------
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                               
------------------------------------------------------------------------
          Fan rotor disk CSN               Initial inspection schedule  
------------------------------------------------------------------------
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:

----------------------------------------------------------------------------------------------------------------
             Document No.                 Pages             Revision                         Date               
----------------------------------------------------------------------------------------------------------------
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.                                                                                                
----------------------------------------------------------------------------------------------------------------

    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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