[Federal Register Volume 65, Number 198 (Thursday, October 12, 2000)]
[Proposed Rules]
[Pages 60597-60599]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-26141]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 90-ANE-25-AD; Amendment No. 39-XXXXX]
RIN 2120-AA64


Airworthiness Directives; General Electric Company (GE) CF-645 
and CF6-50 Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to revise an existing airworthiness 
directive (AD), applicable to certain GE turbofan engines. That AD 
currently requires initial and repetitive inspections of high pressure 
compressor (HPC) rear shafts and installation of a certain rear shaft 
flange bolt configuration. This action would add additional HPC rear 
shaft part numbers for reworked rear shafts to the AD. This proposal is 
prompted by the need to ensure that the additional HPC rear shafts 
listed in this proposed rule receive the same inspections as part 
numbers covered by the current amendment. The actions specified by the 
proposed AD are intended to detect and replace cracked HPC rear shafts, 
which, if not replaced, could lead to an uncontained engine failure.

DATES: Comments must be received by November 16, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 90-ANE-25-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``<a href="/cdn-cgi/l/email-protection#fec7d39f909bd39f9a9d9193939b908abe989f9fd0999188"><span class="__cf_email__" data-cfemail="251c08444b40084441464a4848404b51654344440b424a53">[email protected]</span></a>''. Comments sent 
via the Internet must contain the docket number in the subject line. 
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 Company, Technical Publications Department, 1 Neumann 
Way, Cincinnati, OH 45215. This information may be examined at the FAA, 
New England Region, Office of the Regional 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.

[[Page 60598]]


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 90-ANE-25-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRM's

    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. 90-ANE-25-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    On March 18, 1991, the FAA issued AD 91-10-03, Amendment 39-6956 
(56 FR 19920, May 1, 1991), applicable to GE CF6-45 and CF6-50 turbofan 
engines, to require initial and repetitive inspections of HPC rear 
shafts and installation of a certain rear shaft flange bolt. That 
action was prompted by reports of 35 HPC rear shafts found cracked in 
the bolt hole area. The inspection requirements of that AD were 
intended to detect and replace cracked HPC rear shafts to prevent an 
HPC rear shaft fracture, which could result in an uncontained engine 
failure. On April 4, 1995, the FAA issued AD 91-10-03 Revision 1, 
Amendment 39-9186 (60 FR 1879, May 13, 1995), applicable to GE CF6-45 
and CF6-50 series turbofan engines. That action was prompted by an FAA 
determination that the Parts Manufacturer Approval (PMA) Production 
Approval Listing, Supplement No. 27, authorizes the use of Valley-
Todeco (VT) bolts, part number (P/N) VCD0016, as an alternate to GE 
bolts, P/N 1375M69P01. The VT bolt is identical in design to the GE 
bolt and the amendment adds the VT bolt to the applicability. That 
amendment also clarifies that engines with one or more PMA bolts, P/N 
VCD0016 installed, must accomplish the inspection requirements of the 
original AD, and allow the installation of PMA bolts as alternates to 
the GE bolts. That AD Revision requires initial and repetitive 
inspections to detect and replace cracked HPC rear shafts to prevent an 
HPC rear shaft fracture, which could result in an uncontained engine 
failure.

New Information

    Since that revision to the AD was issued, the FAA has become aware 
of HPC rear shaft rework P/N's that have been issued by the 
manufacturer that are not listed in AD 91-10-03, Revision 1 but should 
be inspected.

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 revise AD 91-10-03 Revision 1 to add HPC rear shaft 
rework P/N's to the AD. The actions would be required to be 
accomplished in accordance with the SB's described previously.

Economic Impact

    There are about 1,730 engines of the affected design in the 
worldwide fleet. The FAA estimates that 469 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take about 2 work hours per engine to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. Required 
labor would cost about $120.00 per engine. Based on these figures, the 
total labor cost impact of the proposed AD on U.S. operators is 
estimated to be $56,280.

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 39-9186 (60 FR 
18729, April 13, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

General Electric Company: Docket No. 90-ANE-25-AD. Revises AD 91-10-
03, Revision 1, Amendment 39-9186.

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

    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 (e)

[[Page 60599]]

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 a high pressure compressor (HPC) rear shaft 
fracture, which could result in an uncontained engine failure and/or 
in-flight engine shutdown, accomplish the following:
    (a) Fluorescent-penetrant inspect HPC rear shafts having the 
part numbers (P/N's) in Table 1 below, in accordance with the 
Accomplishment Instructions of GE Service Bulletin (SB) No. 72-958, 
Revision 1, dated October 18, 1990 as follows:

                                 Table 1
------------------------------------------------------------------------
 
------------------------------------------------------------------------
 9127M58P03        9079M63P12         9079M63P15        9079M63P16
 9079M63P17        9079M63P18         9079M63P19        1999M25P01
 1999M25P02        1999M25P03         1999M25P04        1999M25P05
 1999M25P06        1999M25P07
------------------------------------------------------------------------

    (1) For HPC rear shafts currently installed with hook bolts, P/N 
9012M99G10, 9114M95G07, and 9114M95G10, inspect in accordance with 
the following schedule:
    (i) For shafts that have not been previously inspected and have 
10,000 cycles since new (CSN) or more on the effective date of this 
AD, inspect within the next 1,500 cycles in service (CIS) after the 
effective date of this AD.
    (ii) For shafts that have not been previously inspected and have 
fewer than 10,000 CSN on the effective date of this AD, inspect 
within the next 2,500 CIS from the effective date of this AD, or 
before accumulating 7,500 CSN, whichever occurs later. However, no 
shaft may exceed 11,500 CSN before inspection.
    (iii) For shafts that have been previously inspected and have 
3,000 cycles since last inspection (CSLI) or fewer on the effective 
date of this AD, inspect within 4,500 CSLI, or before accumulating 
7,500 CSN, whichever occurs later.
    (iv) For shafts that have been previously inspected and have 
greater than 3,000 CSLI on the effective date of this AD, inspect 
within the next 1,500 CIS from the effective date of this AD, or 
before accumulating 7,500 CSN, whichever occurs later.
    (v) Remove from service HPC rear shaft hook bolts identified in 
(a)(1) of this AD after any inspection performed in accordance with 
paragraph (a)(1) of this AD and replace with new tapered turn-around 
bolts, P/N 1375M69P01 or VCD0016.
    (2) For HPC rear shafts installed with turn-around bolts, P/N 
9249M54P01, or tapered turn-around bolts, P/N 1375M69P01 or VCD0016, 
inspect in accordance with the following schedule:
    (i) For shafts that have not been previously inspected and have 
6,500 CSN or more on the effective date of this AD, inspect within 
the next 2,500 CIS after the effective date of this AD.
    (ii) For shafts that have not been previously inspected and have 
fewer than 6,500 CSN on the effective date of this AD, inspect 
before accumulating 9,000 CSN.
    (iii) For shafts that have been previously inspected and have 
3,500 CSLI or fewer on the effective date of this AD, inspect within 
6,000 CSLI, or before accumulating 9,000 CSN, whichever occurs 
later.
    (iv) For shafts that have been previously inspected and have 
more than 3,500 CSLI on the effective date of this AD, inspect 
within the next 2,500 CIS after the effective date of this AD, or 
before accumulating 9,000 CSN, whichever occurs later.
    (v) Remove from service HPC rear shaft turn-around bolts 
identified in paragraph (a)(2) of this AD after any inspection 
performed in accordance with paragraph (a)(3) of this AD and replace 
with new tapered turn-around bolts, P/N 1375M69P01 or VCD0016.

    Note 2. Information concerning the tapered turn-around bolt 
noted in paragraph (a) of this proposed AD can be found in GE SB No. 
72-877.

    (b) Remove from service, prior to further flight, any shafts 
found cracked at inspection.
    (c) Thereafter, for shafts that have been inspected in 
accordance with paragraph (a) of this AD, reinspect in accordance 
with the Accomplishment Instructions of GE SB No. 72-958, Revision 
1, dated October 18, 1990, at intervals not to exceed 6,000 CSLI.
    (d) Compliance with paragraph (a) of AD 91-10-03, Revision 1 
satisfies the corresponding requirements of paragraph (a) of this 
AD. For the purposes of this AD, the inspection cycle interval must 
be measured from the last HPC rear shaft bolt hole inspection, 
regardless of any rear shaft rework and re-identifying after 
inspection.

Alternative Methods of Compliance

    (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 (ECO). 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

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

Special Flight Permits

    (f) 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 
requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on October 5, 2000.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-26141 Filed 10-11-00; 8:45 am]
BILLING CODE 4910-13-P


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