[Federal Register Volume 59, Number 1 (Monday, January 3, 1994)]
[Unknown Section]
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From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 93-31908]


Federal Register / Vol. 59, No. 1 / Monday, January 3, 1994 /

[[Page Unknown]]

[Federal Register: January 3, 1994]


                                                     VOL. 59, NO. 1

                                            Monday, January 3, 1994
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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 92-ANE-08; Amendment 39-8781; AD 93-25-17]

 

Airworthiness Directives; General Electric CT7 Series Turboprop 
and 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 (GE) CT7 series turboprop and turboshaft 
engines. This proposal would require the removal from service of 
certain gas generator turbine (GGT) rotor assembly parts that were 
plasma-sprayed during manufacture. This amendment is prompted by 
material testing that indicates that the plasma-spray process reduces 
the low cycle fatigue (LCF) capability of the material. The actions 
specified by this AD are intended to prevent fatigue cracks that can 
result in uncontained engine failure.

DATES: Effective February 2, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register, as 
of February 2, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from General Electric Aircraft Engines, 1000 Western Avenue, 
Lynn, Massachusetts 01910. This information may be examined at the FAA, 
New England Region, Office of the Assistant Chief Counsel, Attn: Rules 
Docket No. 92-ANE-08, 12 New England Executive Park, Burlington, 
Massachusetts 01803-5299; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC 20001.

FOR FURTHER INFORMATION CONTACT: Barbara G. Caufield, Aerospace 
Engineer, Engine Certification Branch, ANE-141, Engine Certification 
Office, FAA, New England Region, Engine and Propeller Directorate, 
Aircraft Certification Service, 12 New England Executive Park, 
Burlington, Massachusetts 01803-5299; telephone (617) 238-7146; fax 
(617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to General Electric CT7 series turboprop and turboshaft 
engines was published in the Federal Register on November 13, 1992 (57 
FR 53862). That action proposed to require the removal from service of 
certain gas generator turbine (GGT) rotor assembly parts that were 
plasma-sprayed during manufacture, and replacement with serviceable 
parts. The actions would be required to be accomplished in accordance 
with GE CT7 Turboprop Service Bulletin (SB) A72-252, dated August 31, 
1990; and GE CT7 Turboshaft SB A72-17 and SB A72-18, both dated 
September 10, 1990.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the rule as proposed.
    One commenter observes that the economic analysis in the proposed 
AD is based on 23 engines being affected by the AD, when, in fact, 
there are only 11 engines containing a combination of 23 parts. The FAA 
concurs. The wording of the economic analysis for the final rule has 
been changed accordingly.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.
    The FAA estimates that 11 engines (containing 23 affected parts) 
installed on aircraft of U.S. registry will be affected by this AD, 
that it will take approximately 7 work hours per engine to accomplish 
the required actions, and that the average labor rate is $55 per work 
hour. Required parts will cost approximately $8,255 per engine. Based 
on these figures, the total cost impact of the AD on U.S. operators is 
estimated to be $95,040. The manufacturer has advised the FAA that a 
pro-rata credit allowance will be granted for labor and parts required 
to accomplish these removals and replacements at a GE authorized 
service or overhaul facility. Based on this information, the FAA has 
determined that the total cost impact of the AD on U.S. operators would 
be approximately $5,940 ($540 per engine).
    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 14 CFR part 
39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

93-25-17. General Electric: Amendment 39-8781. Docket No. 93-ANE-08.

    Applicability: General Electric (GE) Models CT7-5A2, -7A, and -
9C Turboprop Engines; and Models CT7-2A, and -6 Turboshaft Engines, 
incorporating gas generator turbine (GGT) disks and cooling plates, 
as listed by Part Number (P/N) and Serial Number (S/N) in GE CT7 
Turboprop Service Bulletin (SB) A72-252, dated August 31, 1990; GE 
CT7 Turobshaft SB A72-17, and GE CT7 Turboshaft SB A72-18, both 
dated September 10, 1990, installed on, but not limited to, Saab 
340A, Casa CN235-10, Bell 214ST, and European Helicopter Industries 
EH101.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fatigue cracks that can result in uncontained engine 
failure, accomplish the following:
    (a) Remove from service the affected GE Model(s) CT7-5A2, -7A, 
and -9C engines GGT rotor stage 1 and 2 disks, and stage 2 forward 
and aft cooling plates, prior to exceeding the ``Max total allowable 
cycles''; as listed in GE CT7 Turboprop SB A72-252, dated August 31, 
1990, and replace with serviceable parts.
    (b) Remove from service the affected GE Model(s) CT7-6 engine 
GGT rotor stage 1 disk and stage 2 forward cooling plate prior to 
exceeding the ``Max total allowable cycles''; as listed in GE CT7 
Turboprop SB A72-17, dated September 10, 1990, and replace with 
serviceable parts.
    (c) Remove from service the affected GE Model(s) CT7-2A engine 
GGT rotor stage 2 disk and stage 2 forward cooling plate prior to 
exceeding the ``Max total allowable cycles''; as listed in GE CT7 
Turboshaft SB A72-8, dated September 10, 1990, and replace with 
serviceable parts.
    (d) 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: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.
    (e) Special flight permits may be issued, in accordance with FAR 
21.197 and 21.199, to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (f) The removals and replacements of the affected rotor stage 
disks and cooling plates shall be done in accordance with the 
following service bulletins: 

------------------------------------------------------------------------
   Document No.         Page No.            Issue             Date      
------------------------------------------------------------------------
GE CT7 Turboprop    1-13............  Original........  Aug 31, 1990    
 SB A72-252.                                                            
Total pages: 13                                                         
GE CT7 Turboshaft   1-4.............  Original........  Sep 10, 1990    
 SB A72-17.                                                             
Total pages: 4                                                          
GE CT7 Turboshaft   1-4.............  Original........  Sep 10, 1990    
 SB A72-18.                                                             
Total pages: 4                                                          
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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, 1000 Western Avenue, Lynn, Massachusetts 01910. Copies may 
be inspected at the FAA, New England Region, Office of the Assistant 
Chief Counsel, Attn: Rules Docket No. 92-ANE-08, 12 New England 
Executive Park, Burlington, Massachusetts; or at the Office of the 
Federal Register, 800 North Capitol Street NW., suite 700, 
Washington, DC.
    (g) This amendment becomes effective on February 2, 1994.

    Issued in Burlington, Massachusetts, on December 21, 1993.
Jay J. Pardee,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 93-31908 Filed 12-30-93; 8:45 am]
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