[Federal Register Volume 62, Number 188 (Monday, September 29, 1997)]
[Rules and Regulations]
[Pages 50862-50865]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-25581]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-15; Amendment 39-10137; AD 97-19-17]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT58 Series 
Turboshaft Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to General Electric Company CT58 series turboshaft engines, 
that requires removal from service of certain compressor rear shafts, 
initial and repetitive inspections of specific critical rotating parts, 
and replacement if found cracked, until those parts are removed from 
service and replaced with improved design parts. This amendment is 
prompted by a stage 2 turbine wheel

[[Page 50863]]

incident in 1993 which resulted in an increased awareness of small 
features on critical rotating parts which could affect part life. The 
actions specified by this AD are intended to prevent fatigue cracking 
on specific critical rotating parts, which could result in failure of 
the part, causing an uncontained engine failure and damage to the 
aircraft.

DATES: Effective November 28, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 28, 1997.

ADDRESSES: The service information referenced in this AD may be 
obtained from General Electric Aircraft Engines, Technical 
Publications, 1000 Western Avenue, Lynn, MA 01910; telephone (781) 594-
5102, fax (781) 594-2717. This information may be examined at the 
Federal Aviation Administration (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.

FOR FURTHER INFORMATION CONTACT: Diane Cook, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7133, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to General Electric Company (GE) CT58 
series turboshaft engines was published in the Federal Register on 
April 3, 1997 (62 FR 15861). That action proposed to require removal 
from service of certain compressor rear shafts, initial and repetitive 
inspections of specific critical rotating parts, and replacement if 
found cracked, until those parts are removed from service and replaced 
with improved design parts.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposal or the FAA's determination of the cost to the public.
    Since publication of the Notice of Proposed Rulemaking (NPRM), GE 
has issued Revision 2 to GE Aircraft Engines Service Bulletin (SB) No. 
(CT58) 72-181, CEB-284, dated July 15, 1997, which adds serial numbers 
(S/Ns) of certain affected Stage 1 and Stage 2 turbine wheels that 
require inspections. Revision 1 to GE Aircraft Engines SB No. (CT58) 
72-181, CEB-284, dated November 29, 1995, is no longer current and is 
not an acceptable Alternative Method of Compliance (AMOC) for this AD.
    In addition, GE has issued Revision 8 to GE Aircraft Engines SB No. 
(CT58) A72-162, CEB-258, dated June 16, 1997, that makes editorial 
changes to the SB. Revisions 5 through 7 of this SB are considered 
acceptable AMOCs for this AD.
    Also, the FAA has revised the economic analysis to better reflect 
the lower number of affected engines, since not all Stage 1 and Stage 2 
turbine wheels now require inspections, only those listed by S/Ns in GE 
Aircraft Engines SB No. (CT58) 72-181, CEB-284, dated July 15, 1997.
    After careful review of the available data, the FAA has determined 
that air safety and the public interest require the adoption of the 
rule with the changes described previously. The FAA has determined that 
these changes will neither increase the economic burden on any operator 
nor increase the scope of the AD.
    There are approximately 400 engines of the affected design in the 
worldwide fleet. The FAA estimates that 126 engines installed on 
aircraft of U.S. registry will be affected by this AD, that it will 
take approximately zero additional work hours per engine to accomplish 
the required actions. Required parts will cost approximately $2,730 per 
engine, based on the estimated current part cost, as the manufacturer 
will prorate the cost to the operator downward by a factor equal to the 
quotient of the difference between the original life limit (4,000 hours 
time in service) and the total cycles of life consumed at time of 
removal, divided by the original life limit. Based on these figures, 
the total cost impact of the AD on U.S. operators is estimated to be 
$56,650.
    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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action 
and it is contained in the rules docket. A copy of it 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 adding the following new 
airworthiness directive:

97-19-17  General Electric Company: Amendment 39-10137. Docket 97-
ANE-15.

    Applicability: General Electric Company (GE) Models CT58-100-2, 
-110-1/-2, -140-1/-2, and T58-GE-3/-5/-10/-100 turboshaft engines, 
installed on but not limited to Boeing Vertol 107 series, and 
Sikorsky S61 and S62 series aircraft.

    Note 1: 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 request 
approval for an alternative method of compliance in accordance with 
paragraph (f) of this AD. The request should include an assessment 
of the effect of the modification, alteration, or repair on the 
unsafe condition addressed by this AD; and, if the unsafe condition 
has not been eliminated, the request should include specific 
proposed actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fatigue cracking on specific critical rotating parts, 
which could result in failure of the part, causing an uncontained 
engine failure and damage to the aircraft, accomplish the following:
    (a) Determine hours time in service (TIS) and cycles in service 
(CIS) in accordance with the improved methodology described in GE 
Aircraft Engines Service Bulletin (SB) No.

[[Page 50864]]

(CT58) A72-162, CEB-258, Revision 8, dated June 16, 1997.
    (b) For engines that have engaged in repeated heavy lift (RHL) 
operations, as defined in paragraph (e) of this
    AD, accomplish the following:
    (1) For compressor rear shafts, Part Numbers (P/N's) 4000T29P01/
P03, 5016T95P01/P04, and 5013T86P03, accomplish the following:
    (i) For compressor rear shafts, with either 2,975 or more hours 
TIS, or 9,550 or more CIS, on the effective date of this AD, remove 
compressor rear shafts and replace with a serviceable compressor 
rear shaft at the next light overhaul or next exposure of compressor 
rear shafts after the effective date of this AD, whichever occurs 
first.
    (ii) For all other compressor rear shafts, remove compressor 
rear shafts and replace with a serviceable compressor rear shaft, 
prior to accumulating 3,000 hours TIS, or 9,600 CIS, whichever 
occurs first.
    (iii) For all compressor rear shafts, remove from service and 
replace with a serviceable, redesigned compressor rear shaft, P/N 
5016T95P06, not later than December 31, 1997.
    (2) Initially inspect the ten rotating parts specified in 
paragraph (d) of this AD for cracks at the times specified in sub-
paragraphs (i) and (ii) of this paragraph, and, thereafter, inspect 
at each light overhaul or major overhaul until the parts are retired 
from service. Perform the inspections in accordance with the 
procedures described in GE Aircraft Engines SB No. (CT58) 72-181, 
CEB-284, Revision 2, dated July 15, 1997. Prior to further flight, 
replace parts found cracked during these inspections with 
serviceable parts.
    (i) For parts with greater than the baseline time in service 
(TIS) on the effective date of this AD, inspect at the earliest 
occurrence of the following after the effective date of this AD: the 
next light overhaul, the next major overhaul, or the next exposure 
of the affected parts.
    (ii) For parts with less than or equal to the baseline TIS on 
the effective date of this AD, inspect within 1,000 hours TIS from 
the listed baseline TIS.
    (c) For engines that have never engaged in RHL operations, 
accomplish the following:
    (1) For compressor rear shafts, P/N's 4000T29P01/P03, 
5016T95P01/P04, and 5013T86P03, remove compressor rear shafts and 
replace with a serviceable compressor rear shaft, prior to 
accumulating 9,600 CIS, or 9,000 hours TIS, whichever occurs first. 
Prior to December 31, 1999, replace compressor rear shafts with a 
serviceable, redesigned compressor rear shaft, P/N 5016T95P06.
    (2) Initially inspect the ten rotating parts specified in 
paragraph (d) of this AD for cracks at the times specified in sub-
paragraphs (i) and (ii) of this paragraph, and, thereafter, at each 
light overhaul or major overhaul until the parts are retired from 
service. Perform the inspections in accordance with the procedures 
described in GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, 
Revision 2, dated July 15, 1997. Prior to further flight, replace 
parts found cracked during these inspections with serviceable parts.
    (i) For parts with greater than the baseline TIS on the 
effective date of this AD, inspect at the earliest occurrence of the 
following after the effective date of this AD: the next light 
overhaul, the next major overhaul, or the next exposure.
    (ii) For parts with less than or equal to the baseline TIS on 
the effective date of this AD, inspect within 2,000 hours TIS from 
the listed baseline hours.
    (d) For the purpose of performing the inspections required by 
paragraphs (b)(2) and (c)(2) of this AD, the following baseline TIS 
are established:
    (1) For compressor rotor spool assemblies, P/N's 6010T57G04 and 
6010T57G08, whether or not used in RHL operations, baseline is 2,000 
hours TIS.
    (2) For turbine front shafts, P/N's 5003T35P01 and 573D358P002, 
whether or not utilized in RHL operation, baseline is 1,000 hours 
TIS.
    (3) For turbine coupling shafts, P/N's 4001T26P01 and 
278D987P002, if utilized in RHL operation, baseline is 1,000 hours 
TIS; if never utilized in RHL operations, baseline is 2,000 hours 
TIS.
    (4) For turbine rear shafts, P/N's 4005T29P01 and 37D400244P101, 
whether or not utilized in RHL operation, baseline is 2,000 hours 
TIS.
    (5) For Stage 1 front cooling plates, P/N's 37C300055P101, 
whether or not utilized in RHL operation, baseline is 1,000 hours 
TIS.
    (6) For Stage 1 aft cooling plates, P/N's 3002T25P01 and 
645C334P002, whether or not utilized in RHL operation, baseline is 
1,000 hours TIS.
    (7) For Stage 2 front cooling plates, P/N's 3000T88P02 and 
645C332P002, whether or not utilized in RHL operation, baseline is 
1,000 hours TIS.
    (8) For Stage 2 aft cooling plates, P/N's 3002T27P01 and 
645C336P002, whether or not utilized in RHL operation, baseline is 
1,000 hours TIS.
    (9) For Stage 1 turbine wheels, P/N 4002T17P02 TF3, listed by 
Serial Numbers (S/Ns) in paragraph 1.A. (3) of GE Aircraft Engines 
SB No. (CT58) 72-181, CEB-284, Revision 2, dated July 15, 1997, if 
utilized in RHL operation, baseline is 1,000 hours TIS; if never 
utilized in RHL operation, baseline is 2,000 hours TIS.
    (10) For Stage 2 turbine wheels, P/N 4002T96P02 TF3, listed by 
S/Ns in paragraph 1.A. (3) of GE Aircraft Engines SB No. (CT58) 72-
181, CEB-284, Revision 2, dated July 15, 1997, if utilized in RHL 
operation, baseline is 1,000 hours TIS; if never utilized in RHL 
operation, baseline is 2,000 hours TIS.
    (e) For the purpose of this AD, the following definitions apply:
    (1) RHL operation is defined as performing more than 10 lift-
carry-drop cycles per hour TIS without landing, or more than 10 
takeoffs and landings per hour TIS.
    (2) Light overhaul is defined as scheduled engine maintenance 
that allows the engine to continue in service until scheduled major 
overhaul time is reached.
    (3) Major overhaul is defined as scheduled engine maintenance 
including complete engine inspections and tests with repair or 
replacement of parts or components as necessary.
    (f) 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, Engine 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, Engine Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (g) 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 inspection requirements of this AD can be accomplished.
    (h) The actions required by this AD shall be done in accordance 
with the following GE Aircraft Engines SBs:

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                Document number                    Pages      Revision                     Date                 
----------------------------------------------------------------------------------------------------------------
(CT58) 72-181, CEB-284.........................       1-22            2  July 15, 1997.                         
                                                -----------                                                     
      Total pages..............................         22                                                      
                                                ===========                                                     
(CT58) A72-162, CEB-258........................          1            7  April 25, 1997.                        
                                                       2,3            8  June 16, 1997.                         
                                                       4,5            5  May 12, 1994.                          
                                                         6            7  April 25, 1997.                        
                                                       7,8            5  May 12, 1994.                          
                                                     9-11,            7  April 25, 1997.                        
                                                     12-16            5  May 12, 1994.                          
                                                        17            7  April 25, 1997.                        
                                                     18-20            5  May 12, 1994.                          

[[Page 50865]]

                                                                                                                
                                                        21            8  June 16, 1997.                         
                                                     22-24            5  May 12, 1994.                          
                                                    25, 26            7  April 25, 1997.                        
                                                        27            5  May 12, 1994.                          
                                                -----------                                                     
      Total pages..............................         27                                                      
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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 General Electric Aircraft 
Engines, Technical Publications, 1000 Western Avenue, Lynn, MA 
01910; telephone (781) 594-5102, fax (781) 594-2717. 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.
    (i) This amendment becomes effective on November 28, 1997.

    Issued in Burlington, Massachusetts, on September 11, 1997.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 97-25581 Filed 9-26-97; 8:45 am]
BILLING CODE 4910-13-U