[Federal Register Volume 59, Number 86 (Thursday, May 5, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10502]


[[Page Unknown]]

[Federal Register: May 5, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-ANE-41; Amendment 39-8907; AD 94-09-18]

 

Airworthiness Directives; General Electric Company; CF6 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to General Electric Company (GE) CF6-6/-45/-50 series 
turbofan engines, that requires an inspection for cracks in the stage 1 
high pressure turbine (HPT) disk rim bolt holes, and stage 2 HPT disk 
rim and inner bolt holes; and replacement, if necessary, with 
serviceable parts. This amendment is prompted by a report of an 
uncontained stage 1 HPT disk failure which resulted in an aborted 
takeoff. The actions specified by this AD are intended to prevent an 
uncontained stage 1 or stage 2 HPT disk failure, which could result in 
an inflight engine shutdown, rejected takeoff, or damage to the 
aircraft.

DATES: Effective June 6, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 6, 1994.

ADDRESSES: The service information referenced in this AD 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 Federal Aviation Administration 
(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: 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: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to General Electric Company (GE) CF6-6/-45/-50 series 
turbofan engines was published as a notice of proposed rulemaking 
(NPRM) in the Federal Register on October 19, 1993 (58 FR 53893). That 
action proposed to require an eddy current inspection for cracks in the 
stage 1 high pressure turbine (HPT) disk rim bolt holes, and stage 2 
HPT disk rim and inner bolt holes; and replacement, if necessary, with 
serviceable parts. The inspection, and replacement, if necessary, would 
be performed in accordance with GE CF6-6 Service Bulletin (SB) No. 72-
1002, dated February 12, 1993; CF6-6 SB No. 72-1003, Revision 1, dated 
June 17, 1993; CF6-50 SB No. 72-1057, Revision 1, dated June 17, 1993; 
and CF6-50 SB No. 72-1059, dated February 12, 1993.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the rule as proposed.
    One commenter states that the compliance end-date of February 28, 
1994, in compliance paragraph (b)(6) of the proposed rule should be 
replaced by 1,000 cycles in service (CIS) after the effective date of 
this AD, in order to avoid forced engine removals. The FAA concurs. 
This change is consistent with the results of the failure analysis 
performed by the manufacturer, and is supported by the positive 
inspection results to date. This final rule has been revised 
accordingly.
    One commenter states that the compliance end-date of February 28, 
1994, in compliance paragraph (b)(6) of the proposed rule should be 
extended to one year after the effective date of this AD, in order to 
avoid forced engine removals. The FAA concurs in part. The FAA agrees 
that the current compliance end-date may cause forced engine removals; 
however, an extension of this date alone may still cause an undue 
burden on low cycle/low time operators. A cyclic definition in lieu of 
a compliance end-date will help alleviate this potential problem. The 
manufacturer has informed the FAA that a typical operator accumulates 
approximately 1,000 CIS in one year. This change is consistent with the 
results of the failure analysis performed by the manufacturer, and is 
supported by the positive inspection results to date. Therefore, the 
compliance end-date of February 28, 1994, in paragraph (b)(6) in the 
proposed rule has been replaced in this final rule by 1,000 CIS after 
the effective date of this AD.
    Two commenters state that the compliance end-date of May 31, 1994, 
in compliance paragraph (a)(1) and (a)(2) should be removed, and 4,500 
cycles since new (CSN) should be replaced by 5,400 CSN to avoid forced 
engine removals. The FAA concurs. This change is consistent with the 
results of the failure analysis performed by the manufacturer, and is 
supported by the positive inspection results to date. This final rule 
has been revised accordingly.
    Two commenters state that the compliance end-date of May 31, 1994, 
in compliance paragraph (a)(3) should be replaced by 1,400 CIS after 
the effective date of this AD to avoid forced engine removals. The FAA 
concurs. This change is consistent with the results of the failure 
analysis performed by the manufacturer, and is supported by the 
positive inspection results to date. This final rule has been revised 
accordingly.
    Two commenters state that the compliance end-date of February 28, 
1994, in compliance paragraphs (a)(4)(i) and (a)(4)(ii) should be 
removed, 3,500 CSN should be replaced by 4,500 CSN, and 3,000 CSN 
should be replaced by 3,500 CSN to avoid forced engine removals. The 
FAA concurs in part. The FAA agrees that the current compliance end-
date may cause forced engine removals, but the proposed CSN changes are 
not consistent with the results of the failure analysis performed by 
the manufacturer. The results of this analysis suggest that 3,500 CSN 
can be changed to 4,000 CSN; however, 3,000 CSN can not be changed. 
This final rule has been revised accordingly.
    Two commenters state that the compliance end-date of February 28, 
1994, in compliance paragraph (a)(4)(iii) should be replaced by 1,000 
CIS after the effective date of this AD, and 3,000 CSN should be 
replaced by 3,500 CSN to avoid forced engine removals. The FAA concurs 
in part. The FAA agrees that the current compliance end-date may cause 
forced engine removals, but the proposed CSN change is not consistent 
with the results of the failure analysis performed by the manufacturer. 
The results of this analysis suggest that 3,000 CSN can not be changed. 
This final rule has been revised accordingly.
    One commenter states that the compliance end-date of May 31, 1994, 
in compliance paragraphs (a)(5)(i) and (a)(5)(ii) should be removed, 
and 4,500 CSN should be replaced by 6,000 CSN to avoid forced engine 
removals. The FAA concurs in part. The FAA agrees that the current 
compliance end-date may cause forced engine removals, but the proposed 
CSN change is not consistent with the results of the failure analysis 
performed by the manufacturer. The results of this analysis suggest 
that 4,500 CSN can be changed to 5,400 CSN. The final rule has been 
revised accordingly.
    One commenter states that the compliance end-date of May 31, 1994, 
in compliance paragraph (a)(5)(iii) should be replaced by 2,000 CIS 
after the effective date of this AD to avoid forced engine removals. 
The FAA concurs in part. The FAA agrees that the current compliance 
end-date may cause forced engine removals, but the proposed CIS is not 
consistent with the results of this failure analysis performed by the 
manufacturer. The results of this analysis suggest that 1,400 CIS is 
appropriate. This final rule has been revised accordingly.
    Although no comments were received regarding compliance paragraphs 
(b)(1) to (b)(5), the FAA has changed these paragraphs to be consistent 
with the corresponding paragraphs in paragraph (a) of this final rule.
    The economic analysis section of the proposed rule assumed that all 
inspected disks would require replacement. The manufacturer has 
informed the FAA that this assumption is overly conservative based on 
analysis and inspection results to date, and that only approximately 2% 
of the inspected disks will require replacement. The 2% figure 
translates to approximately 10 disks installed on aircraft of U.S. 
registry. The economic analysis section of this final rule has been 
revised accordingly.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 650 GE CF6-6/-45/-50 series turbofan 
engines of the affected design in the worldwide fleet. The FAA 
estimates that 500 engines installed on aircraft of U.S. registry will 
be affected by this AD, that it will take approximately 108 work hours 
per engine to accomplish the required actions, and that the average 
labor rate is $55 per work hour. Required parts will cost approximately 
$77,314 per engine. Based on these figures, and assuming that 10 of the 
inspected disks will require replacement, the total cost impact of the 
AD on U.S. operators is estimated to be $3,743,140.
    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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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 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:

94-09-18 General Electric Company: Amendment 39-8907. Docket 93-ANE-
41

    Applicability: General Electric Company (GE) CF6-6/ -45/-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 an uncontained stage 1 or stage 2 high pressure 
turbine (HPT) disk failure, which could result in an inflight engine 
shutdown, rejected takeoff, or damage to the aircraft, accomplish 
the following:
    (a) Eddy current inspect (ECI) stage 1 and stage 2 HPT disks for 
cracks in accordance with the Accomplishment Instructions of GE CF6-
6 Service Bulletin (SB) No. 72-1002, dated February 12, 1993, and 
CF6-6 SB No. 72-1003, Revision 1, dated June 17, 1993, as follows:
    (1) For GE CF6-6 series stage 1 HPT disks, Part Numbers (P/N) 
9137M40P01 and 9687M39P07, with serial numbers (S/N) listed in 
Appendix I or II of GE CF6-6 SB No. 72-1002, dated February 12, 
1993, which have accumulated less than 2,500 cycles since new (CSN) 
on the effective date of this airworthiness directive (AD), ECI the 
rim bolt holes at the next engine shop visit after accumulating 
2,500 CSN, but not to exceed 5,400 CSN.
    (2) For GE CF6-6 series stage 1 HPT disks, P/N 9137M40P01 and 
9687M39P07, with S/N listed in Appendix I or II or GE CF6-6 SB No. 
72-1002, dated February 12, 1993, which have accumulated 2,500 CSN 
or more, but less than 4,000 CSN on the effective date of this AD, 
ECI the rim bolt holes at the next engine shop visit, but not to 
exceed 5,400 CSN.
    (3) For GE CF6-6 series stage 1 HPT disks, P/N 9137M40P01 and 
9687M39P07, with S/N listed in Appendix I or II of GE CF6-6 SB No. 
72-1002, dated February 12, 1993, which have accumulated 4,000 CSN 
or more on the effective date of this AD, ECI the rim bolt holes at 
the next engine shop visit, or prior to accumulating 1,400 cycles in 
service (CIS) after the effective date of this AD, whichever occurs 
earlier.
    (4) For GE CF6-6 series stage 2 HPT disks, P/N 9084M52P02 and 
9084M52P05, with
S/N listed in Appendix I or II of GE CF6-6 SB No. 72-1003, Revision 
1, dated June 17, 1993, which have not accomplished the inner bolt 
hole ECI prior to the effective date of this AD in accordance with 
GE CF6-6 Shop Manual, GEK 9266, Chapter 72-53-04, accomplish the 
following:
    (i) For disks which have accumulated less than 2,000 CSN on the 
effective date of this AD, ECI the rim and inner bolt holes at the 
next engine shop visit after accumulating 2,000 CSN, but not to 
exceed 4,000 CSN.
    (ii) For disks which have accumulated 2,000 CSN or more, but 
less than 3,000 CSN on the effective date of this AD, ECI the rim 
and inner bolt holes at the next engine shop visit, but not to 
exceed 4,000 CSN.
    (iii) For disks which have accumulated 3,000 CSN or more on the 
effective date of this AD, ECI the rim and inner bolt holes at the 
next engine shop visit, or prior to accumulating 1,000 CIS after the 
effective date of this AD, whichever occurs earlier.
    (5) For GE CF6-6 series stage 2 HPT disks, P/N 9084M52P02 and 
9084M52P05, with
S/N listed in Appendix I or II of GE CF6-6 SB No. 72-1003, Revision 
1, dated June 17, 1993, which have accomplished the inner bolt hole 
ECI prior to the effective date of this AD in accordance with GE 
CF6-6 Shop Manual, GEK 9266, Chapter 72-53-04, and not found 
cracked, accomplish the following:
    (i) For disks which have accumulated less than 2,000 CSN on the 
effective date of this AD, ECI the rim and inner bolt holes at the 
next engine shop visit after accumulating 2,000 CSN, but not to 
exceed 5,400 CSN.
    (ii) For disks which have accumulated 2,000 CSN or more, but 
less than 4,000 CSN on the effective date of this AD, ECI the rim 
and inner bolt holes at the next engine shop visit, prior to 
accumulating 4,500 CSN, but not to exceed 5,400 CSN.
    (iii) For disks which have accumulated 4,000 CSN or more on the 
effective date of this AD, ECI the rim and inner bolt holes at the 
next engine shop visit, or prior to accumulating 1,400 CIS after the 
effective date of this AD, whichever occurs earlier.
    (6) GE CF6-6 series stage 1 HPT disks referenced in paragraphs 
(a)(1), (a)(2), and (a)(3) of this AD, that have been inspected by 
ECI in accordance with the procedures outlined in GE CF6-6 All 
Operators Wire (AOW) 92-6-09, dated September 24, 1992, or GE CF6-6 
Engine Shop Manual, GEK 9266, Chapter 72-53-03, prior to the 
effective date of this AD, and whose CSN at the time of inspection 
was 2,500 or more, already meet the inspection requirements of 
paragraphs (a)(1), (a)(2), and (a)(3) of this AD.
    (7) GE CF6-6 series stage 2 HPT disks referenced in paragraphs 
(a)(4) and (a)(5) of this AD, that have been inspected by ECI in 
accordance with the procedures outlined in GE CF6-6 AOW 92-6-09, 
dated September 24, 1992; GE CF6-6 SB No. 72-1003, dated February 
12, 1993; or GE CF6-6 Engine Shop Manual, GEK 9266, Chapter 72-53-
04, prior to the effective date of this AD, and whose CSN at the 
time of inspection was 2,000 or more, already meet the inspection 
requirements of paragraphs (a)(4) and (a)(5) of this AD.
    (b) ECI stage 1 and stage 2 HPT disks for cracks in accordance 
with the Accomplishment Instructions of GE CF6-50 SB No. 72-1057, 
Revision 1, dated June 17, 1993, and CF6-50 SB No. 72-1059, dated 
February 12, 1993, as follows:
    (1) For GE CF6-45/-50 series stage 1 HPT disks, P/N 9283M31P02, 
9283M55P04, and 9283M55P05, with S/N listed in Appendix I, II, or 
III of GE CF6-50 SB No. 72-1059, dated February 12, 1993, which have 
accumulated less than 2,500 CSN on the effective date of this AD, 
ECI the rim bolt holes at the next engine shop visit after 
accumulating 2,500 CSN, but not to exceed 5,400 CSN.
    (2) For GE CF6-45/-50 series stage 1 HPT disks, P/N 9283M31P02, 
9283M55P04, and 9283M55P05, with S/N listed in Appendix I, II, or 
III of GE CF6-50 SB No. 72-1059, dated February 12, 1993, which have 
accumulated 2,500 CSN or more, but less than 4,000 CSN on the 
effective date of this AD, ECI the rim bolt holes at the next engine 
shop visit, but not to exceed 5,400 CSN.
    (3) For GE CF6-45/-50 series stage 1 HPT disks P/N 9283M31P02, 
9283M55P04, and 9283M55P05, with S/N listed in Appendix I, II, or 
III of GE CF6-50 SB No. 72-1059, dated February 12, 1993, which have 
accumulated 4,000 CSN or more on the effective date of this AD, ECI 
the rim bolt holes at the next engine shop visit, or prior to 
accumulating 1,400 CIS after the effective date of this AD, 
whichever occurs earlier.
    (4) For GE CF6-45/-50 series stage 2 HPT disks, P/N 9045M35P18 
and 1474M49P06, with S/N listed in the Appendix of GE CF6-50 SB No. 
72-1057, Revision 1, dated June 17, 1993, which have accumulated 
less than 2,000 CSN on the effective date of this AD, ECI the rim 
and inner bolt holes at the next engine shop visit after 
accumulating 2,000 CSN, but not to exceed 4,000 CSN.
    (5) For GE CF6-45/-50 series stage 2 HPT disks, P/N 9045M35P18 
and 1474M49P06, with S/N listed in the Appendix of GE CF6-50 SB No. 
72-1057, Revision 1, dated June 17, 1993, which have accumulated 
2,000 CSN or more, but less than 3,000 CSN on the effective date of 
this AD, ECI the rim bolt holes at the next engine shop visit, but 
not to exceed 4,000 CSN.
    (6) For GE CF6-45/-50 series stage 2 HPT disks, P/N 9045M35P18 
and 1474M49P06, with S/N listed in the Appendix of GE CF6-50 SB No. 
72-1057, Revision 1, dated June 17, 1993, which have accumulated 
3,000 CSN or more on the effective date of this AD, ECI the rim and 
inner bolt holes at the next engine shop visit, or prior to 
accumulating 1,000 CIS after the effective date of this AD, 
whichever occurs earlier.
    (7) GE CF6-45/-50 series stage 1 HPT disks referenced in 
paragraphs (b)(1), (b)(2), and (b)(3) of this AD, that have been 
inspected by ECI in accordance with the procedures outlined in GE 
CF6-50 AOW 92-50-15, dated September 24, 1992, or GE CF6-50 Engine 
Task Numbered Shop Manual, GEK 50481, Chapter 72-53-03, prior to the 
effective date of this AD, and whose CSN at the time of inspection 
was 2,500 or more, already meet the inspection requirements of 
paragraphs (b)(1), (b)(2), and (b)(3) of this AD.
    (8) GE CF6-45/-50 series stage 2 HPT disks referenced in 
paragraphs (b)(4), (b)(5), and (b)(6) of this AD, that have been 
inspected by ECI in accordance with the procedures outlined in GE 
CF6-50 AOW 92-50-15, dated September 24, 1992; GE CF6-50 SB No. 72-
1057, dated February 12, 1993; or GE CF6-50 Engine Task Numbered 
Shop Manual, GEK 50481, Chapter 72-53-04, prior to the effective 
date of this AD, and whose CSN at the time of inspection was 2,000 
or more, already meet the inspection requirements of paragraphs 
(b)(4), (b)(5), and (b)(6) of this AD.
    (c) Remove from service disks found cracked, and replace with 
serviceable parts. Inspect replacement disks in accordance with 
paragraphs (a) or (b) of this AD, if applicable.
    (d) 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 flange.
    (e) 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.

    (f) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the aircraft to a location where 
the requirements of this AD can be accomplished.
    (g) The inspections shall be done in accordance with the 
following service bulletins:

----------------------------------------------------------------------------------------------------------------
                  Document No.                        Pages             Revision                  Date          
----------------------------------------------------------------------------------------------------------------
GE CF6-6 SB                                                                                                     
    No. 72-1002.................................            1-12  Original............  February 12, 1993.      
Total Pages: 12.                                                                                                
GE CF6-6 SB                                                                                                     
    No. 72-1003.................................             1-3  1...................  June 17, 1993.          
                                                            4-21  Original............  February 12, 1993.      
Total Pages: 21.                                                                                                
GE CF6-50 SB                                                                                                    
    No. 72-1057.................................             1-2  1...................  June 17, 1993.          
                                                            3-14  Original............  February 12, 1993.      
Total Pages: 14.                                                                                                
GE CF6-50 SB                                                                                                    
    No. 72-1059.................................            1-17  Original............  February 12, 1993       
Total Pages: 17.                                                                                                
----------------------------------------------------------------------------------------------------------------

    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, CF6 Distribution Clerk, Room 132, 111 Merchant Street, 
Cincinnati, OH 45246. 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.
    (h) This amendment becomes effective on June 6, 1994.

    Issued in Burlington, Massachusetts, on April 26, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 94-10502 Filed 5-4-94; 8:45 am]
BILLING CODE 4910-13-P