[Federal Register Volume 59, Number 138 (Wednesday, July 20, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17328]


[[Page Unknown]]

[Federal Register: July 20, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-ANE-07; Amendment 39-8972; AD 94-15-01]

 

Airworthiness Directives; General Electric Aircraft Engines CT7 
Series Turboprop Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule, request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to General Electric Aircraft Engines (GE) CT7 series 
turboprop engines. This action requires a one-time ultrasonic 
inspection of a suspect population of propeller shafts for 
metallurgical defects, and if necessary, replacement with a serviceable 
part. This amendment is prompted by a report of an inflight propeller 
separation due to a metallurgical defect. The actions specified in this 
AD are intended to prevent failure of the propeller shaft, which can 
result in separation of the propeller from the propeller shaft and 
possible damage to the aircraft.

DATES: Effective August 4, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 4, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before September 19, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 94-ANE-07, 12 New England 
Executive Park, Burlington, MA 01803-5299.
    The service information referenced in this AD may be obtained from 
General Electric Aircraft Engines, 1000 Western Avenue, Lynn, MA 01910. 
This information may be examined 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.

FOR FURTHER INFORMATION CONTACT: Daniel Kerman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7130, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
has determined that certain propeller shafts on General Electric 
Aircraft Engines (GE) CT7 series turboprop engines may have a 
metallurgical defect that could cause separation of the propeller from 
the propeller shaft. The FAA's investigation has revealed this 
population of propeller shafts may contain a metallurgical defect known 
as a pipe inclusion, which developed during manufacture of the shaft. 
This defect typically forms during the process of melting the ingot 
used to form the shaft and positions itself at either end of the ingot. 
During this phase of the manufacturing process cropping both ends of 
the ingot normally ensures complete removal of such defects. The FAA 
has determined, however, that for five heat lots of material, pipe 
inclusions may not have been completely removed from the material used 
to form the propeller shaft. The FAA has determined that suspect 
material was used to manufacture approximately 326 propeller shafts.
    The FAA received a report of a propeller separating from a SAAB-
SCANIA SF340 series aircraft inflight following severe vibration. The 
FAA's investigation revealed that the propeller shaft separated due to 
a pipe inclusion defect positioned in a high stress location of the 
propeller shaft. That defect initiated a crack which propagated to 
failure. This condition, if not corrected, could result in failure of 
the propeller shaft, which can result in separation of the propeller 
from the propeller shaft and possible damage to the aircraft.
    The FAA has reviewed and approved the technical contents of GE 
(CT7-TP Series) Service Bulletin (SB) No. A72-350, Revision 3, dated 
June 9, 1994, that describes procedures for a one-time ultrasonic 
inspection of the propeller shaft flange outer diameter (OD) fillet 
radius and inner diameter (ID) bore for detection of subsurface 
defects. In addition, Table 3 of this SB lists by propeller gearbox 
serial number (S/N) a certain population of suspect propeller shafts to 
be identified by internal markings during a one-time borescope 
inspection. Those propeller shafts with markings identified as suspect 
in accordance with this SB must be ultrasonically inspected prior to 
further flight.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other GE CT7 series turboprop engines of the same 
type design, this airworthiness directive (AD) is being issued to 
prevent separation of the propeller from the propeller shaft, which 
could result in damage to the aircraft. This AD requires a one-time 
ultrasonic inspection of the propeller shaft flange OD fillet radius 
and ID bore on a suspect population of propeller shafts for subsurface 
metallurgical defects, and if necessary, replacement with a serviceable 
part. This inspection must be performed at the next shop visit after 
the effective date of this AD, or prior to October 31, 1994, whichever 
occurs first. The FAA has determined that the compliance end-date of 
October 31, 1994, will be necessary to ensure timely inspection of all 
propeller shafts and thus minimize the potential for additional 
propeller shaft failures. The actions are required to be accomplished 
in accordance with the service bulletin 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 94-ANE-07.'' 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. 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:

94-15-01  General Electric Aircraft Engines: Amendment 39-8972. 
Docket 94-ANE-07.

    Applicability: General Electric Aircraft Engines (GE) Models 
CT7-5A2, -5A3, -7A, -7A1, -9B, -9B1, -9B2, -9C, -9D turboprop 
engines, with propeller gearboxes listed by serial number in GE 
(CT7-TP Series) Service Bulletin (SB) No. A72-350, Revision 3, dated 
June 9, 1994. These engines are installed on but not limited to 
Construcciones Aeronauticas, SA (CASA) CN-235 series and SAAB-SCANIA 
SF340 series aircraft.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the propeller shaft, which can result in 
separation of the propeller from the propeller shaft and possible 
damage to the aircraft, accomplish the following:
    (a) Perform a one-time ultrasonic inspection of the propeller 
shaft flange outer diameter (OD) fillet radius and inner diameter 
(ID) bore for subsurface metallurgical defects, and replace, if 
necessary, with a serviceable part, at the next shop visit after the 
effective date of this AD, or prior to October 31, 1994, whichever 
occurs first. Perform the ultrasonic inspection, and replacement, if 
necessary, in accordance with GE (CT7-TP Series) SB No. A72-350, 
Revision 3, dated June 9, 1994, on propeller shafts listed by 
propeller gearbox serial number (S/N) in Table 2 of that SB.
    (b) Perform a one-time borescope inspection to identify all 
markings on the propeller shaft at the next shop visit after the 
effective date of this AD, or prior to October 31, 1994, whichever 
occurs first. Perform the borescope inspection in accordance with GE 
(CT7-TP Series) SB No. A72-350, Revision 3, dated June 9, 1994, on 
propeller shafts listed by propeller gearbox S/N in Table 3 of that 
SB, and before further flight, proceed as follows:
    (1) For those propeller shafts that are determined to be 
suspect, perform a one-time ultrasonic inspection, and replace, if 
necessary with serviceable parts, in accordance with the 
Accomplishment Instructions of GE (CT7-TP Series) SB No. A72-350, 
Revision 3, dated June 9, 1994.
    (2) For those propeller shafts that are determined not to be 
suspect, no further action is required.
    (c) For the purpose of this AD, a shop visit is defined as the 
induction of the engine into the shop for maintenance, or separation 
of the propeller for maintenance.
    (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 
Sec. Sec. 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.
    (f) The inspections, and replacement, if necessary, shall be 
done in accordance with the following service document: 

------------------------------------------------------------------------
                                            Revision                    
           Document No.             Pages                    Date       
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GE (CT7-TP Series) SB No. A72-350.    1-40         3  June 9, 1994.     
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Total pages: 40.                                                        

    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, MA 01910. 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.
    (g) This amendment becomes effective on August 4, 1994.

    Issued in Burlington, Massachusetts, on July 8, 1994.
Michael H. Borfitz,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 94-17328 Filed 7-19-94; 8:45 am]
BILLING CODE 4910-13-P