Airworthiness Directives; General Electric Company CT64-820-4 Turboprop Engines

[Federal Register Volume 71, Number 75 (Wednesday, April 19, 2006)]
[Rules and Regulations]
[Pages 20001-20005]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3724]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23705; Directorate Identifier 2005-NE-45-AD; 
Amendment 39-14567; AD 2006-08-10]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT64-820-4 
Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
General Electric Company (GE) CT64-820-4 turboprop engines with certain 
part number (P/N) rotating parts. The parts are in the compressor rotor 
assembly, gas generator turbine rotor assembly, and power turbine rotor 
assembly that are subject to low-cycle fatigue. This AD requires 
removing from service these affected rotating parts at reduced 
compliance times. This AD results from the manufacturer's discovery of 
cracks in some rotating parts. We are issuing this AD to prevent cracks 
in the rotating parts that could cause compressor and turbine wheel 
fracture and uncontained engine failure. An uncontained engine failure 
could cause possible damage to the airplane.

DATES: This AD becomes effective May 24, 2006.

ADDRESSES: Use one of the following addresses to comment on this AD:
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact GE Aircraft Engines Customer Support Center, M/D 285, 1 
Neumann Way, Evendale, OH 45215, telephone (513) 552-3272; fax (513) 
552-3329; e-mail address: [email protected], for the service 
information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Anthony W. Cerra Jr., Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803; 
telephone 781-238-7128; fax 781-238-7199; e-mail address: 
[email protected].

SUPPLEMENTARY INFORMATION: GE has informed us that cracks have been 
found in certain P/N rotating parts. The manufacturer reported that 
cracks were found in the outer rim of a stage 1 aft cooling plate, P/N 
4022T37P01, installed on the gas generator turbine (GGT) rotor of a 
military T64 engine. They also found cracks in the sawcut slots of the 
GGT rear air seals of stage 2 aft cooling plates, P/N 4022T36P01, in 
the CT64-820-4 engine model and a similar military T64 engine model. 
There have been at least 13 reports of cracked GGT rear air seals.
    Investigation by the manufacturer showed that compressor rotor 
assemblies, GGT rotor assemblies, and power turbine rotor assemblies 
have small feature locations. A ``small feature'' location is any 
rotating hardware feature with drawing radii less than 0.020 inch. 
Engineering analysis determined that the small feature locations and 
other life-limited locations of the rotating parts identified in this 
action have levels of stress during engine operation that are higher 
than originally anticipated and could result in cracks on these parts. 
This condition, if not corrected, could cause compressor and turbine 
wheel fracture and uncontained engine failure. An uncontained engine 
failure could cause possible damage to the airplane.

FAA's Determination and Requirements of This AD

    Although no airplanes registered in the United States use these 
engines, the possibility exists that the engines could be used on 
airplanes that are registered in the United States in the future. The 
unsafe condition described previously is likely to exist or develop on 
other GE CT64-820-4 turboprop engines of the same type design. We are 
issuing this AD to prevent cracks in the rotating parts that could 
cause compressor and turbine wheel fracture and uncontained engine 
failure. An uncontained engine failure could cause possible damage to 
the airplane. This AD requires removing from service these affected 
life-limited rotating parts at reduced compliance times.

FAA's Determination of the Effective Date

    Since there are currently no domestic operators of this engine 
model, notice and opportunity for public comment before issuing this AD 
are unnecessary. A situation exists that allows the immediate adoption 
of this regulation.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety and was not preceded by notice and an opportunity for public 
comment; however, we invite you to send us any written relevant data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``AD Docket No. FAA-2006-23705; 
Directorate Identifier 2005-NE-45-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify it. We will post all comments we receive, 
without change, to http://dms.dot.gov, including any personal 
information you provide. We will also post a report summarizing each 
substantive verbal contact with FAA personnel concerning this AD. Using 
the search function of the DMS Web site,

[[Page 20002]]

anyone can find and read the comments in any of our dockets, including 
the name of the individual who sent the comment (or signed the comment 
on behalf of an association, business, labor union, etc.). You may 
review the DOT's complete Privacy Act Statement in the Federal Register 
published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the AD, any comments 
received, and any final disposition in person at the Docket Management 
Facility Docket Offices between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays. The Docket Office (telephone (800) 
647-5227) is located on the plaza level of the Department of 
Transportation Nassif Building at the street address stated in 
ADDRESSES. Comments will be available in the AD docket shortly after 
the DMS receives them.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect 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. For the 
reasons discussed above, I certify that the regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act. We prepared a summary of the costs 
to comply with this AD and placed it in the AD Docket. You may get a 
copy of this summary at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

0
Under 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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2006-08-10 General Electric Company: Amendment 39-14567. Docket No. 
FAA-2006-23705; Directorate Identifier 2005-NE-45-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective May 24, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to General Electric Company (GE) CT64-820-4 
turboprop engines that use any of the rotating parts listed in Table 
1 of this AD. These engines are installed on, but not limited to, 
DeHavilland DHC-5D Buffalo airplanes.

                    Table 1.--Affected Rotating Parts
------------------------------------------------------------------------
         Rotor assembly             Part nomenclature        Part No.
------------------------------------------------------------------------
Compressor.....................  Shaft, Front...........      5007T03P03
                                 Disk, Stage 1..........      5015T92P01
                                 Retainer, Disk, Stage 1      5013T71P01
                                 Disk, Stage 2..........      5015T93P01
                                 Spacer, Disk, Stage 2..      5015T94P01
                                 Disk, Stage 3..........      5015T95P01
                                 Spool, Rotor, Front....      6003T84P02
                                 Spool, Rotor, Rear.....      6005T18P01
                                 Shaft, Rear............      6005T26P01
Gas Generator Turbine..........  Disk and Shaft, Stage 1      6014T70P02
                                 Disk, Stage 2..........      4007T83P02
                                 Ring, Torque...........      3008T60P02
                                 Seal, Air, Stage 1.....      4007T94G02
                                 Plate, Cooling.........      3008T52P02
                                 Plate, Cooling.........      4022T37P01
                                 Seal, Interstage.......      5006T54P02
                                 Seal, Air, Rear........      4022T36P01
                                 Seal, Air, Rear........      4022T36P03
Power Turbine..................  Disk, Stage 3..........      4008T65P02
                                 Disk, Stage 4..........      5006T16P03
                                 Disk, Stage 4..........      5006T16P04
                                 Seal, Interstage.......      4008T29P01
                                 Shaft, Main............      5009T73P02
                                 Shaft, Main............      6012T83P02
                                 Tiebolt, Power Turbine       3008T44P02
                                  Rotor.
------------------------------------------------------------------------


[[Page 20003]]

Unsafe Condition

    (d) This AD results from the manufacturer's discovery of cracks 
in some rotating parts. We are issuing this AD to prevent cracks in 
the rotating parts that could cause compressor and turbine wheel 
fracture and uncontained engine failure. An uncontained engine 
failure could cause possible damage to the airplane.

Definition of ``Data Fleet'' and ``No-Data'' Fleet Engines

    (e) For the purposes of this AD, ``Data Fleet'' is defined as a 
category of engines for which the engine serial numbers (SNs) are 
listed in Table 2 of this AD, and the following information has been 
provided to the manufacturer and included in the data analysis:
    (1) Current configuration of all life-limited parts.
    (2) Current cycles of life-limited parts.
    (3) Engine utilization rate (hours/month).

                                     Table 2.--Engine SNs in the Data Fleet
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
           268504                 268565                 268605                 268646                 268662
           268505                 268569                 268606                 268647                 268666
           268509                 268573                 268608                 268648                 268667
           268511                 268574                 268620                 268649                 268669
           268514                 268575                 268622                 268650                 268670
           268529                 268580                 268636                 268653                 268672
           268534                 268583                 268637                 268655                 268674
           268535                 268588                 268638                 268656                 268679
           268537                 268589                 268641                 268658                 268686
           268545                 268590                 268642                 268659                 268689
           268549                 268596                 268643                 268660                 268690
           268562                 268603                 268644                 268661                 268691
----------------------------------------------------------------------------------------------------------------

    (f) For the purposes of this AD, ``No-Data Fleet'' is defined as 
a category of engines for which the engine SNs are not listed in 
Table 2 of this AD. The operators of the ``No Data Fleet'' engines 
did not supply the data listed in paragraph (e) to the manufacturer.

Compliance

    (g) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.
    (h) If performing the actions required by this AD for ``Data 
Fleet'' engines, follow paragraphs (j) through (o).
    (i) If performing the actions required by this AD for ``No-Data 
Fleet'' engines, follow paragraphs (p) through (u).

Data Fleet Rotating Part Removal Requirements

    (j) For parts listed in Table 3 of this AD and installed in 
serviceable engines (those that are in service or have met the 
requirements for and have been approved for return to service) on 
the effective date of this AD, do the following:
    (1) If the cycles-since-new (CSN) of a part listed in Table 3 of 
this AD are equal to or more than Table 3, Limit 2 as of the 
effective date of this AD, remove the part before exceeding 900 
additional cycles-in-service (CIS) or Table 3, Limit 1, whichever 
occurs first, but not later than July 31, 2013.
    (2) If the CSN for a part listed in Table 3 of this AD are fewer 
than Table 3, Limit 2 as of the effective date of this AD, remove 
the part from service before exceeding Table 3, Limit 3, but not 
later than July 31, 2013.

                                            Table 3.--Affected Data Fleet Rotating Part Removal Requirements
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              Limit 1         Limit 2         Limit 3
                     Rotor                                     Nomenclature                  Part No.        (cycles)        (cycles)        (cycles)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Compressor.....................................  Shaft, Front...........................      5007T03P03          30,000          29,100          30,000
                                                 Disk, Stage 1..........................      5015T92P01          13,000           8,100           9,000
                                                 Retainer, Disk, Stage 1................      5013T71P01          30,000          29,100          30,000
                                                 Disk, Stage 2..........................      5015T93P01          23,000           8,100           9,000
                                                 Spacer, Disk, Stage 2..................      5015T94P01          30,000           8,100           9,000
                                                 Disk, Stage 3..........................      5015T95P01           9,000           8,100           9,000
                                                 Spool, Rotor, Front....................      6003T84P02           5,100           2,100           3,000
                                                 Spool, Rotor, Rear.....................      6005T18P01          19,000           3,500           4,400
                                                 Shaft, Rear............................      6005T26P01          30,000           8,100           9,000
Gas Generator Turbine..........................  Disk and Shaft, Stage 1................      6014T70P02           7,000            6100            7000
                                                 Disk, Stage 2..........................      4007T83P02          11,300           5,400           6,300
                                                 Ring, Torque...........................      3008T60P02          30,000           6,100           7,000
                                                 Seal, Air, Stage 1.....................      4007T94G02          30,000          11,700          12,600
                                                 Plate, Cooling.........................      3008T52P02           5,000           4,100           5,000
                                                 Plate, Cooling.........................      4022T37P01           5,000           4,100           5,000
                                                 Seal, Interstage.......................      5006T54P02           5,100           4,200           5,100
                                                 Seal, Air, Rear........................      4022T36P01           5,000           4,100           5,000
                                                 Seal, Air, Rear........................      4022T36P03           5,000           4,100           5,000
Power Turbine..................................  Disk, Stage 3..........................      4008T65P02          30,000          12,100          13,000
                                                 Disk, Stage 4..........................      5006T16P03          30,000          12,100          13,000
                                                 Disk, Stage 4..........................      5006T16P04          30,000          12,100          13,000
                                                 Seal, Interstage.......................      4008T29P01          30,000          12,100          13,000
                                                 Shaft, Main............................      5009T73P02          13,000          12,100          13,000
                                                 Shaft, Main............................      6012T83P02          13,000          12,100          13,000
                                                 Tiebolt, Power Turbine Rotor...........      3008T44P02          13,000          12,100          13,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (k) For all rotating parts listed in Table 3 of this AD and put 
into service after the effective date of this AD, remove from 
service before the CSN exceeds Table 3, Limit 3, but not later than 
July 31, 2013.

[[Page 20004]]

    (l) After the effective date of this AD:
    (1) Do not install any part listed in Table 3 of this AD that 
has a CSN equal to or more than Table 3, Limit 3.
    (2) If the CSN for a part listed in Table 3 of this AD are fewer 
than Table 3, Limit 3:
    (i) Until July 31, 2007, you may return the part to service, if 
the part passes the applicable inspections specified in the CT64-
820-4 Engine Overhaul Manual, SEI-448.
    (ii) You must remove the part from service before Table 3, Limit 
3 is exceeded, but no later than July 31, 2013.
    (iii) After July 31, 2007, do not install any part listed in 
Table 3 of this AD.
    (m) On July 31, 2007, for engines in service that have a part 
listed in Table 3 of this AD, remove the affected part before 
exceeding Table 3, Limit 3, but no later than July 31, 2013.
    (n) For main shafts, P/N 5009T73P02, and P/N 6012T83P02, and 
power turbine rotor tiebolt, P/N 3008T44P02, with unknown CSN do the 
following:
    (1) Assign each part a CSN value of 7,400 CSN as of the 
effective date of this AD and refer to Table 3 of this AD for 
removal requirements.
    (2) Continue to track the parts starting from 7,400 CSN and 
remove from service as specified in paragraphs (j) through (n) of 
this AD, but no later than July 31, 2013.
    (o) For rear air seal, P/N 4022T36P03, and power turbine stage 4 
disk, P/N 5006T16P04, with unknown CSN, remove the part before 
exceeding 10 additional cycles, but no later than July 31, 2013.

No-Data Fleet Rotating Part Removal Requirements

    (p) For parts listed in Table 4 of this AD and installed in 
serviceable engines (those that are in service, or have met the 
requirements for and have been approved for return to service) on 
the effective date of this AD, do the following:
    (1) If the CSN of a part listed in Table 4 of this AD are equal 
to or more than Table 4, Limit 2 as of the effective date of this 
AD, remove the part before exceeding 50 additional CIS or Table 4, 
Limit 1, whichever occurs first, but not later than July 31, 2013.
    (2) If the CSN for a part listed in Table 4 of this AD are fewer 
than Table 4, Limit 2 as of the effective date of this AD, remove 
the part from service before exceeding Table 4, Limit 3, but not 
later than July 31, 2013.
    (q) For all rotating parts listed in Table 4 of this AD and put 
into service after the effective date of this AD, remove from 
service before the CSN exceeds Table 4, Limit 3, but not later than 
July 31, 2013.

                                           Table 4.--Affected No-Data Fleet Rotating Part Removal Requirements
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              Limit 1         Limit 2         Limit 3
                     Rotor                                     Nomenclature                  Part No.        (cycles)        (cycles)        (cycles)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Compressor.....................................  Shaft, Front...........................      5007T03P03          30,000          29,950          30,000
                                                 Disk, Stage 1..........................      5015T92P01          13,000           8,950           9,000
                                                 Retainer, Disk, Stage 1................      5013T71P01          30,000          29,950          30,000
                                                 Disk, Stage 2..........................      5015T93P01          23,000           8,950           9,000
                                                 Spacer, Disk, Stage 2..................      5015T94P01          30,000           8,950           9,000
                                                 Disk, Stage 3..........................      5015T95P01           9,000           8,950           9,000
                                                 Spool, Rotor, Front....................      6003T84P02           5,100           2,950           3,000
                                                 Spool, Rotor, Rear.....................      6005T18P01          19,000           4,350           4,400
                                                 Shaft, Rear............................      6005T26P01          30,000           8,950           9,000
Gas Generator Turbine..........................  Disk and Shaft, Stage 1................      6014T70P02           7,000           6,950           7,000
                                                 Disk, Stage 2..........................      4007T83P02          11,300           6,250           6,300
                                                 Ring, Torque...........................      3008T60P02          30,000           6,950           7,000
                                                 Seal, Air, Stage 1.....................      4007T94G02          30,000          12,550          12,600
                                                 Plate, Cooling.........................      3008T52P02           5,000           4,950           5,000
                                                 Plate, Cooling.........................      4022T37P01           5,000           4,950           5,000
                                                 Seal, Interstage.......................      5006T54P02           5,100           5,050           5,100
                                                 Seal, Air, Rear........................      4022T36P01           5,000           4,950           5,000
                                                 Seal, Air, Rear........................      4022T36P03           5,000           4,950           5,000
Power Turbine..................................  Disk, Stage 3..........................      4008T65P02          30,000          12,950          13,000
                                                 Disk, Stage 4..........................      5006T16P03          30,000          12,950          13,000
                                                 Disk, Stage 4..........................      5006T16P04          30,000          12,950          13,000
                                                 Seal, Interstage.......................      4008T29P01          30,000          12,950          13,000
                                                 Shaft, Main............................      5009T73P02          13,000          12,950          13,000
                                                 Shaft, Main............................      6012T83P02          13,000          12,950          13,000
                                                 Tiebolt, Power Turbine Rotor...........      3008T44P02          13,000          12,950          13,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (r) After the effective date of this AD:
    (1) Do not install any part listed in Table 4 of this AD that 
has a CSN equal to or more than Table 4, Limit 3.
    (2) If the CSN for a part listed in Table 4 of this AD are fewer 
than Table 4, Limit 3:
    (i) Until July 31, 2007, you may return the part to service, if 
the part passes the applicable inspections specified in the CT64-
820-4 Engine Overhaul Manual, SEI-448.
    (ii) You must remove the part from service before Table 4, Limit 
3 is exceeded, but no later than July 31, 2013.
    (iii) After July 31, 2007, do not install any part listed in 
Table 4 of this AD.
    (s) On July 31, 2007, for engines in service that have a part 
listed in Table 4 of this AD, remove the affected part before 
exceeding Table 4, Limit 3, but no later than July 31, 2013.
    (t) For main shafts P/N 5009T73P02, and P/N 6012T83P02, and 
power turbine rotor tiebolt, PN 3008T44P02, with unknown CSN, remove 
the part before exceeding 50 additional cycles
    (u) For rear air seal, P/N 4022T36P03, and power turbine stage 4 
disk, P/N 5006T16P04, with unknown CSN, remove the part before 
exceeding 10 additional cycles, but no later than July 31, 2013.

Log Book Entry

    (v) For all engines, calculate the cycles remaining on the 
affected rotating parts and make an entry in the Engine Log Book 
marked with the engine S/N and its fleet category, either ``DATA 
FLEET'' or ``NO-DATA FLEET.''
    (1) Date and file the record in the Engine Log Book.
    (2) Note in the Engine Log Book that AD 2006-08-10 has been 
complied with.

Alternative Methods of Compliance

    (w) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (x) GE Aircraft Engines CT64 Alert Service Bulletin CT64 S/B 72-
A0130, dated January 24, 2006, pertains to the subject of this AD.


[[Page 20005]]


    Issued in Burlington, Massachusetts, on April 12, 2006.
Francis A. Favara,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3724 Filed 4-18-06; 8:45 am]
BILLING CODE 4910-13-P

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