[Federal Register Volume 59, Number 7 (Tuesday, January 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-588]


[[Page Unknown]]

[Federal Register: January 11, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-ANE-69]

 

Airworthiness Directives; General Electric Company CF6 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to General Electric Company (GE) CF6-
45/-50 series turbofan engines. This proposal would require repetitive 
inspections of the left compressor discharge pressure (CDP) manifold 
and lower CDP tube for cracks, and if found cracked, rework or 
replacement with serviceable parts. This proposal would also require 
rework or replacement of the left CDP manifold, lower CDP tube, stage 
14 turnbuckle, and other related CDP bleed air hardware, and inspection 
of the compressor rear frame (CRF) as a terminating action to the 
inspection program. This proposal is prompted by reports of cracks in 
the left CDP manifold, lower CDP tube, and CRF bleed port struts, that 
have resulted in inflight engine shutdowns and rejected takeoffs. The 
actions specified by the proposed AD are intended to prevent cracks in 
the left CDP manifold, lower CDP tube, and CRF bleed port struts, which 
could result in an inflight engine shutdown, rejected takeoff, or 
damage to the engine nacelle.

DATES: Comments must be received by March 14, 1993.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 93-ANE-69, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location between 8 a.m. and 4:30 p.m., Monday through Friday, 
except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from General Electric Aircraft Engines, CF6 Distribution 
Clerk, room 132, 111 Merchant Street, Cincinnati, OH 45246. This 
information may be examined at the FAA, New England Region, Office of 
the Assistant Chief Counsel, 12 New England Executive Park, Burlington, 
MA.

FOR FURTHER INFORMATION CONTACT: Robert J. Ganley, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7138; fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal 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 93-ANE-69.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 93-ANE-69, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    This proposed airworthiness directive (AD) is applicable to General 
Electric Company (GE) CF6-45/-50 series turbofan engines. The Federal 
Aviation Administration (FAA) has received 228 reports of cracks in the 
left compressor discharge pressure (CDP) manifold, lower CDP tube, and 
compressor rear frame (CRF) bleed port struts. Of these 228 reports, 24 
have resulted in inflight engine shutdowns, and 24 in rejected 
takeoffs. The current type design hardware has been found to crack, 
allowing hot air to leak into the core cowl area, resulting in false 
fire warnings.
    The cracks in the current type design hardware are the result of 
high cycle fatigue (HCF). The excessive stress is the result of both 
thermal and airframe installation loading factors. New hardware exists 
which decreases operating stresses, therefore reducing the chance of 
cracks due to HCF. This condition, if not corrected, may result in 
cracks in the left CDP manifold, lower CDP tube, and CRF bleed port 
struts, which could result in an inflight engine shutdown, rejected 
takeoff, or damage to the engine nacelle.
    The FAA has reviewed and approved the technical contents of GE CF6-
50 Service Bulletin (SB) No. 75-065, Revision 1, dated March 26, 1993, 
that describes procedures for rework or replacement of the left CDP 
manifold, lower CDP tube, and other related CDP bleed air hardware, and 
inspection of the CRF bleed port struts; GE CF6-50 SB No. 75-067, dated 
March 15, 1993, that describes procedures for rework or replacement of 
the stage 14 turnbuckle; and GE CF6-50 SB No. 75-064, Revision 2, dated 
July 23, 1992, that describes procedures for repetitive inspections of 
the left CDP manifold and lower CDP tube for cracks.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require repetitive inspections of the left CDP 
manifold and lower CDP tube for cracks, and if found cracked, rework or 
replacement with serviceable parts. This proposal would also require 
rework or replacement of the left CDP manifold, lower CDP tube, stage 
14 turnbuckle, and other related CDP bleed air hardware, and inspection 
of the CRF as a terminating action to the inspection program. The 
compliance end-date of October 31, 1996, is proposed to ensure timely 
compliance. Based upon engine shop visit rates, a compliance end-date 
of October 31, 1996, will ensure timely compliance while minimizing the 
number of forced engine removals. The actions would be required to be 
accomplished in accordance with the service bulletins described 
previously.
    There are approximately 2202 GE CF6-45/-50 series engines of the 
affected design in the worldwide fleet. The FAA estimates that 223 
engines installed on aircraft of U.S. registry would be affected by 
this proposed AD, that it would take approximately 2 work hours per 
engine to accomplish the proposed inspections, 32 work hours per engine 
to accomplish the proposed terminating action, and that the average 
labor rate is $55 per work hour. Required parts would cost 
approximately $27,500 per engine. Based on these figures, the total 
cost impact of the proposed AD on U.S. operators is estimated to be 
$6,549,510.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
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) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 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:

General Electric Company: Docket No. 93-ANE-69.

    Applicability: General Electric Company (GE) CF6-5/-50 series 
turbofan engines installed on but not limited to Airbus A300 series, 
Boeing 747 series, and McDonnell Douglas DC-10 series aircraft.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent cracks in the left compressor discharge pressure 
(CDP) manifold, lower CDP tube, and the compressor rear frame (CRF) 
bleed port struts, which could result in an inflight engine 
shutdown, rejected takeoff, or damage to the engine nacelle, 
accomplish the following:
    (a) Inspect the left CDP manifold, Part Number (P/N) 9057M84G02 
and 9057M84G03, and lower CDP tube, P/N 9068M40G01, in accordance 
with GE CF6-50 Service Bulletin (SB) No. 75-064, Revision 2, dated 
July 23, 1992, within the next 500 hours time in service (TIS) or 
150 cycles in service (CIS) after the effective date of this 
airworthiness directive (AD), whichever occurs later. Thereafter, 
inspect at intervals not to exceed 500 hours TIS or 150 CIS since 
the last inspection, whichever occurs later.
    (b) For left CDP manifolds and lower CDP tubes found cracked, 
accomplish the following prior to further flight:
    (1) Rework or replace the left CDP manifold, lower CDP tube, and 
other related CDP bleed air hardware, and fluorescent penetrant 
inspect (FPI) the CRF in accordance with GE CF6-50 SB No. 75-065, 
Revision 1, dated March 26, 1993. For CRF's found cracked, either 
repair in accordance with GE CF6-50 Task Number Shop Manual, GEK 
50481, Chapter 72-34-01, or replace with a serviceable part.
    (2) Rework or replace the stage 14 turnbuckle, P/N 1555M42P01, 
in accordance with GE CF6-50 SB No. 75-067, dated March 15, 1993.
    (c) Rework or replace the left CDP manifold, P/N 9057M84G02 and 
9057M84G03, lower CDP tube, P/N 9068M40G01, and other related CDP 
bleed air hardware, and FPI the CRF in accordance with GE CF6-50 SB 
No. 75-065, Revision 1, dated March 26, 1993, at the next engine 
shop visit, or by October 31, 1996, whichever occurs earlier. For 
CRF's found cracked, either repair in accordance with GE CF6-50 Task 
Number Shop Manual, GEK 50481, Chapter 72-34-01, or replace with a 
serviceable part.
    (d) Rework or replace the stage 14 turnbuckle, P/N 1555M42P01, 
in accordance with GE CF6-50 SB No. 75-067, dated March 15, 1993, at 
the next engine shop visit, or by October 31, 1996, whichever occurs 
earlier.
    (e) Rework or replacement of the left CDP manifold, lower CDP 
tube, and stage 14 turnbuckle, in accordance with paragraph (b), or 
paragraphs (c) and (d), as applicable, of this AD constitutes 
terminating action to the repetitive inspections required in 
paragraph (a) of this AD.
    (f) For the purpose of this AD, an engine shop visit is defined 
as the induction of an engine into a shop for maintenance involving 
the separation of any major module.
    (g) 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.

    (h) 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.

    Issued in Burlington, Massachusetts, on December 27, 1993.
Jay J. Pardee,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 94-588 Filed 1-10-94; 8:45 am]
BILLING CODE 4910-13-P