[Federal Register Volume 60, Number 66 (Thursday, April 6, 1995)]
[Proposed Rules]
[Pages 17487-17489]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8444]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-10]


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 an initial 
and repetitive on-wing visual inspection of the side links of the five-
link forward mount assembly for cracks, and replacement of the side 
links and pylon attachment bolts, and inspection of the fail-safe bolt 
and platform lug, if the side links are found cracked. This proposal 
would also require a shop-level refurbishment of the side links as a 
terminating action to the on-wing inspection program. This proposal is 
prompted by four reports of cracked side links detected during routine 
engine shop visits. The actions specified by the proposed AD are 
intended to prevent a side link fracture, which could result in the 
failure of the second side link, or the forward engine mount pylon 
attachment bolts, and possible separation of the engine from the 
aircraft.

DATES: Comments must be received by May 8, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 95-ANE-10, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location between 8:00 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 95-ANE-10.'' 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 [[Page 17488]] Assistant 
Chief Counsel, Attention: Rules Docket No. 95-ANE-10, 12 New England 
Executive Park, Burlington, MA 01803-5299.

Discussion

    This proposed airworthiness directive (AD) is applicable to the 
General Electric Company (GE) CF6-45/-50 series turbofan engines. The 
Federal Aviation Administration (FAA) has received four reports of 
cracked side links of the five-link forward mount assembly. These 
cracks were detected during routine engine shop visits. Metallurgical 
analysis performed on the fractured side links indicate that the 
cracking is the result of stress corrosion. Stress corrosion cracking 
occurs when the protective coating is locally missing, allowing 
corrosive materials to come in contact with the base material of the 
side link. Preliminary analysis conducted with a simulated side link 
failure indicates that the second side link, or the pylon attachment 
bolts depending on the type of aircraft, may not be capable of 
withstanding the resulting loads in this configuration. A shop-level 
refurbishment procedure exists which enhances the durability of the 
side links' protective coating, therefore reducing the chance of cracks 
due to stress corrosion. This condition, if not corrected, could result 
in a side link fracture, which could result in the failure of the 
second side link or the forward engine mount pylon attachment bolts, 
and possible separation of the engine from the aircraft. The 
requirements of this AD have been reviewed by the Transport Airplane 
Directorate.
    The FAA has reviewed and approved the technical contents of GE 
Aircraft Engines CF6-50 Service Bulletin No. 72-1092, dated November 
18, 1994, that describes procedures for the initial and repetitive on-
wing visual inspection and side link refurbishment.
    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 an initial and repetitive on-wing visual 
inspection of the side links of the five-link forward mount assembly 
for cracks, replacement of the side links and pylon attachment bolts, 
and inspection of the fail-safe bolt and platform lug, if side links 
are found cracked. This proposal would also require a shop-level 
refurbishment of the side links as a terminating action to the on-wing 
inspection program.
    The FAA estimates that 220 engines installed on aircraft of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 7.5 work hours per engine to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. The FAA 
has estimated that only a small percentage of parts will actually 
require replacement as a result of this AD, and therefore, has 
determined the parts cost to be negligible. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be $99,000.

    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 (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:

General Electric Company: Docket No. 95-ANE-10.

    Applicability: General Electric Company (GE) CF6-45/-50 series 
turbofan engines installed on, but not limited to, Airbus A300 
series, Boeing 747 series, and McDonnell Douglas DC-10 series 
aircraft.

    Note: This 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 use the authority provided in paragraph (d) to 
request approval from the FAA. This approval may address either no 
action, if the current configuration eliminates the unsafe 
condition, or different actions necessary to address the unsafe 
condition described in this AD. Such a request should include an 
assessment of the effect of the changed configuration on the unsafe 
condition addressed by this AD. In no case does the presence of any 
modification, alteration, or repair remove any engine from the 
applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent a side link fracture, which could result in failure 
of the second side link, or the forward engine mount pylon 
attachment bolts, and possible separation of the engine from the 
aircraft, accomplish the following:
    (a) Inspect left-hand side links, Part Numbers (P/N) 9204M94P01, 
9204M94P03, and 9346M99P01, and right-hand side links, P/N's 
9204M94P02, 9204M94P04, and 9346M99P02, that have not had the side 
link refurbishment done in accordance with GE CF6-50 Task Numbered 
Shop Manual, GEK 50481, Chapter 72-23-11, including Temporary 
Revision No. 72-0821 and 72-0822, both dated November 1, 1994, as 
follows:
    (1) For side links that have not been previously inspected in 
accordance with GE Aircraft Engines (GEAE) CF6-50 Service Bulletin 
(SB) No. 72-1092, dated November 18, 1994, inspect in accordance 
with paragraph 2.A of GEAE CF6-50 SB No. 72-1092, dated November 18, 
1994, prior to accumulating 350 cycles in service (CIS), or 750 
hours time in service (TIS), after the effective date of this AD, 
whichever occurs earlier.
    (2) For side links that have been previously inspected in 
accordance with GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, 
inspect in accordance with paragraph 2.A of GEAE CF6-50 SB No. 72-
1092, dated November 18, 1994, prior to accumulating 350 CIS, or 750 
hours TIS since inspected in accordance with GEAE CF6-50 SB No. 72-
1092, dated November 18, 1994, whichever occurs earlier.
    (3) Thereafter, inspect in accordance with paragraph 2.A of GEAE 
CF6-50 SB No. 72-1092, dated November 18, 1994, at intervals 
[[Page 17489]] not to exceed 350 CIS, or 750 hours TIS since the 
last inspection, whichever occurs earlier.
    (4) If side links are found cracked, replace the cracked side 
links and pylon attachment bolts with serviceable parts, and inspect 
the fail-safe bolt and platform lug in accordance with paragraph 2.B 
of GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, prior to 
further flight.
    (b) Refurbish the left-hand and right-hand side links identified 
in paragraph (a) of this AD at the next engine shop visit after the 
effective date of this AD in accordance with paragraph 2.C of GEAE 
CF6-50 SB No. 72-1092, dated November 18, 1994. Refurbishment of 
side links in accordance with this paragraph constitutes terminating 
action to the on-wing inspection requirements of paragraph (a) of 
this AD.
    (c) 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 the fan and core modules.
    (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 alternate 
methods of compliance with this airworthiness directive, if any, may 
be obtained from the Engine Certification Office.

    Issued in Burlington, Massachusetts, on March 22, 1995.
James C. Jones,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 95-8444 Filed 4-3-95; 1:31 pm]
BILLING CODE 4910-13-P