[Federal Register Volume 65, Number 140 (Thursday, July 20, 2000)]
[Proposed Rules]
[Pages 44997-44999]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-18406]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-35-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-80A3 
Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to General Electric Company 
CF6-80A3 series turbofan engines. The existing AD currently requires 
initial and repetitive on-wing borescope inspections of the left hand 
aft engine mount link assembly for cracks, bearing migration, and, 
bearing race rotation, and if necessary, replacement with serviceable 
parts. This proposal would require initial and repetitive visual 
inspections of both left hand and right hand aft engine mount link 
assemblies for separations, cracks, and bearing race migration. Cracked 
or separated parts would have to be replaced prior to further flight. 
If spherical bearing race migration is discovered, a borescope 
inspection for cracks is also proposed. If no cracks are discovered by 
the additional borescope inspection, assemblies would have a 75-cycle 
grace period for remaining in service before replacement. Finally, 
installation of improved aft engine mount link assemblies would 
constitute terminating action to the inspections of this proposed AD. 
This proposal is prompted by a recent analysis of internal bearing 
friction and bearing migration and inspections which revealed migrated 
spherical bearing races on two CF6-80A3 series and ten CF6-80C2 series 
aft engine mount links. The actions specified by the proposed AD are 
intended to prevent aft engine mount link failure, which can result in 
adverse redistribution of the aft engine mount loads and possible aft 
engine mount system failure.

DATES: Comments must be received by September 18, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 98-ANE-35-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. Comments sent 
via the Internet must contain the docket number in the subject line. 
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 Rohr, Inc., 850 Lagoon Dr., Chula Vista, CA 91910-2098; 
telephone 619-691-3102, fax 619-498-7215. This information may be 
examined at the FAA, New England Region, Office of the Regional 
Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Karen Curtis, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone 781-
238-7192, fax 781-238-7199.

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 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 98-ANE-35-AD.'' 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 Regional Counsel, 
Attention: Rules Docket No. 98-ANE-35-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    On July 15, 1998, the Federal Aviation Administration (FAA) issued 
airworthiness directive (AD) 98-15-17, Amendment 39-10668 (63 FR 39489, 
July 23, 1998), applicable to General Electric Company (GE) CF6-80A3 
series turbofan engines. That AD requires initial and repetitive on-
wing borescope inspections of the left hand aft engine mount link 
assembly for cracks, bearing migration, and bearing race rotation, and, 
if necessary, replacement with serviceable parts. That action was

[[Page 44998]]

prompted by a report of a fractured left hand aft engine mount link 
discovered during a scheduled engine removal. That condition, if not 
corrected, could result in aft engine mount link failure, which can 
result in adverse redistribution of the aft mount loads and possible 
aft mount system failure.
    Due to the similarities between the link assembly designs, on June 
28, 2000, the FAA also published a comparable rule for CF6-80C2 engine 
models installed on A300, A310, and MD-11 applications (AD 2000-12-08).

Recent Analysis

    Since the issuance of AD 98-15-17, analysis into internal bearing 
friction and bearing race migration that could result in higher stress 
levels and reduced fatigue capability of aft engine mount links has 
been conducted. The analysis indicates that aft engine mount link 
spherical bearing race migration adversely affects link fatigue life 
and that right hand, as well as left hand, aft engine mount link 
assemblies are affected. Recent inspections also revealed migrated 
spherical bearing races on two CF6-80A3 series and ten CF6-80C2 series 
aft engine mount links. This condition, if not corrected, could result 
in aft engine mount link failure, which can result in adverse 
redistribution of the aft engine mount loads and possible aft engine 
mount system failure.

Service Information

    The FAA has reviewed and approved the technical contents of Rohr 
Service Bulletin CF6-80A3-NAC-A71-064, dated April 4, 2000, that 
describes the aft engine mount link replacement. The FAA also has 
reviewed and approved the technical contents of Rohr Service Bulletin 
CF6-80A3-NAC-A71-061, Revision 1, dated February 22, 2000, that 
describes procedures for visual inspections of existing left hand and 
right hand aft engine mount link assemblies for separations, cracks, 
and spherical bearing race migration and provides rejection criteria.

Proposed Actions

    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 supersede AD 98-15-17 to require initial and 
repetitive visual inspections of both left hand and right hand aft 
engine mount link assemblies for separations, cracks, and bearing race 
migration. If bearing race migration is discovered, this proposal would 
require a borescope inspection for cracks. Aft engine mount link 
assemblies found cracked would have to be replaced with serviceable 
parts prior to further flight. Aft engine mount link assemblies 
discovered with bearing race migration would be able to remain in 
service for another 75 cycles-in-service (CIS) following borescope 
inspection prior to replacement with serviceable parts. All left hand 
and right hand aft engine mount link assemblies would have to be 
replaced at the next engine shop visit with improved assemblies, which 
would constitute terminating action to the inspections. These actions 
would be required to be accomplished in accordance with the service 
bulletins described previously.

Economic Analysis

    There are approximately 120 engines of the affected design in the 
worldwide fleet. The FAA estimates that 59 engines installed on 
aircraft of US registry would be affected by this proposed AD, that the 
cost of replacement link assemblies is approximately $9,737, that it 
would take approximately 2 work hours per engine to accomplish the 
proposed interim inspections, and that the average labor rate is $60 
per work hour. Based on these figures, the total cost impact of the 
proposed AD over 3 years on US operators is estimated to be $588,614.

Regulatory Impact

    This proposal does not have federalism implications, as defined in 
Executive Order 13132, because it would not have a substantial direct 
effect 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. Accordingly, 
the FAA has not consulted with state authorities prior to publication 
of this proposal.
    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 
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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-10668 (63 FR 
39489, July 23, 1998) and by adding a new airworthiness directive to 
read as follows:

General Electric Company: Docket No. 98-ANE-35-AD. Supersedes AD 98-
15-17, Amendment 39-10668.

    Applicability: General Electric Company (GE) CF6-80A3 series 
turbofan engines, with left hand aft engine mount link assemblies, 
part numbers (P/Ns) 224-1608-501, 224-1608-503, or 224-1608-505 
installed, or right hand aft engine mount link assemblies, P/Ns 224-
1609-503, 224-1609-505, or 224-1609-507 installed. These engines are 
installed on but not limited to Airbus Industrie A310-200 series 
aircraft.

    Note 1: This airworthiness directive (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 request 
approval for an alternative method of compliance in accordance with 
paragraph (d) of this AD. The request should include an assessment 
of the effect of the modification, alteration, or repair on the 
unsafe condition addressed by this AD; and, if the unsafe condition 
has not been eliminated, the request should include specific 
proposed actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent aft engine mount link failure, which can result in 
adverse redistribution of the aft engine mount loads and possible 
aft engine mount system failure, accomplish the following:

Initial Inspection

    (a) Inspect aft engine mount link assemblies as follows:

Not Previously Inspected

    (1) Within 400 cycles-in-service (CIS) after the effective date 
of this AD, if not previously inspected using Rohr Service Bulletin 
CF6-80A3-NAC-A71-061, Revision 1, dated

[[Page 44999]]

February 22, 2000, or Rohr Service Bulletin CF6-80A3-NAC-A71-061, 
dated April 16, 1999; or

Previously Inspected

    (2) Within 400 cycles-since-last-inspection (CSLI), if 
previously inspected using Rohr Service Bulletin CF6-80A3-NAC-A71-
061, Revision 1, dated February 22, 2000, or Rohr Service Bulletin 
CF6-80A3-NAC-A71-061, dated April 16, 1999.
    (3) Visually inspect for: separations, cracks, and spherical 
bearing race migration.
    (4) Inspect in accordance with the Accomplishment Instructions 
of Rohr Service Bulletin CF6-80A3-NAC-A71-061, Revision 1, dated 
February 22, 2000.

Cracked or Separated Parts

    (5) If a crack or separation is discovered, prior to further 
flight, remove the cracked or separated aft engine mount link 
assembly and the attaching hardware from service, and replace with 
serviceable parts.

Removal of Aft Engine Mount Link Assemblies With Spherical Bearing Race 
Migration

    (6) If an aft engine mount link assembly is found with spherical 
bearing race migration, but no cracks or separations, prior to 
further flight, do either of the following:

Removal

    (i) Remove the aft engine mount link assembly and the attaching 
hardware from service and replace with serviceable parts; or

Additional Borescope Inspection of Aft Engine Mount Link Assemblies 
With Spherical Bearing Race Migration

    (ii) Perform an additional borescope inspection for cracks in 
accordance with paragraphs (2)(D)(5) and (2)(G)(5) of the 
Accomplishment Instructions of Rohr Service Bulletin CF6-80A3-NAC-
A71-061, Revision 1, dated February 22, 2000, and perform the 
following:

After Additional Borescope Inspection, if Parts Are Cracked

    (A) If a crack indication is discovered, prior to further 
flight, remove the cracked aft engine mount link assembly and the 
attaching hardware from service, and replace with serviceable parts.

After Additional Borescope Inspection, If Parts Are Not Cracked (Grace 
Period)

    (B) If crack indications are not discovered, within 75 CIS after 
the inspection performed in accordance with paragraph (a)(6)(ii) of 
this AD, remove the aft engine mount link assembly from service, and 
replace with serviceable parts.

Attaching Hardware

    (iii) Attaching hardware may be returned to service after 
inspection in accordance with paragraphs 2(D)(6)(a) or 2(G)(6)(a) of 
Rohr Service Bulletin CF6-80A3-NAC-A71-061, Revision 1, dated 
February 22, 2000, only if inspection of the removed link shows no 
cracks or separations.

    Note 2: Link attaching hardware includes the nuts, bolts and 
washers that secure the link.

Repetitive Inspections

    (b) Thereafter, perform the actions required by paragraph (a) 
and associated subparagraphs at intervals not to exceed 400 CSLI.

Replacement With Improved Link Assemblies

    (c) Replace aft engine mount link assemblies with improved aft 
engine mount link assemblies at the next engine shop visit (ESV), or 
prior to accumulating 29,000 engine cycles since new (CSN), 
whichever occurs first.
    (1) Replace in accordance with the Accomplishment Instructions 
of Rohr Service Bulletin CF6-80A3-NAC-A71-064, dated April 4, 2000.

Left Hand Aft Engine Mount Link Assemblies

    (2) Replace left hand aft engine mount link assemblies, P/Ns 
224-1608-501, 224-1608-503, or 224-1608-505, with improved left hand 
aft engine mount link assemblies, P/Ns 224-1608-507 or 224-1608-509.

Right Hand Aft Engine Mount Link Assemblies

    (3) Replace right hand aft engine mount link assemblies, P/Ns 
224-1609-503, 224-1609-505, or 224-1609-507, with improved right 
hand aft engine mount link assemblies, P/Ns 224-1609-509 or 224-
1609-511.

Terminating Action

    (4) Installation of improved aft engine mount link assemblies in 
accordance with paragraph (c) and its subparagraphs constitutes 
terminating action to the inspections required by paragraphs (a) and 
(b) of this AD.

Alternate Methods of Compliance

    (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. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

Ferry Flights

    (e) Special flight permits may be issued in accordance with 
Secs. 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 
inspection requirements of this AD can be accomplished.


    Issued in Burlington, Massachusetts, on July 14, 2000.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-18406 Filed 7-19-00; 8:45 am]
BILLING CODE 4910-13-U