[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
