[Federal Register Volume 59, Number 84 (Tuesday, May 3, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10503]
[[Page Unknown]]
[Federal Register: May 3, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-ANE-11]
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 notice proposes the supersedure of an existing
airworthiness directive (AD), applicable to General Electric Company
(GE) CF6-45/-50/-80A series turbofan engines, that currently requires a
one-time ultrasonic and eddy current inspection of the high pressure
compressor rotor (HPCR) stage 3-9 spool for cracks. This action would
retain the inspection requirements of the current AD, but would
accelerate the inspection schedule, and introduce a repetitive
inspection requirement. This proposal is prompted by a review of the
inspection results to date, which indicate that the crack occurrence
rate is higher than initially projected. The actions specified by the
proposed AD are intended to prevent an uncontained HPCR stage 3-9 spool
failure, which could result in damage to the aircraft.
DATES: Comments must be received by June 2, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 94-ANE-11, 12 New England
Executive Park, Burlington, MA 01803-5299. 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 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 94-ANE-11.'' 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 Assistant Chief Counsel,
Attention: Rules Docket No. 94-ANE-11, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
On October 25, 1991, the Federal Aviation Administration (FAA)
issued airworthiness directive (AD) 91-20-01, Amendment 39-8035 (56 FR
55230), to require a one-time ultrasonic and eddy current inspection of
the high pressure compressor rotor (HPCR) stage 3-9 spool for cracks.
That action was prompted by two reports of spools found cracked in
service. That condition, if not corrected, could result in an
uncontained HPCR stage 3-9 spool failure, which could result in damage
to the aircraft.
Since the issuance of that AD, the FAA has received reports of five
additional spools found cracked in service. Investigation indicates
that the cracks initiated in sub-surface origins in the stage 9 bore
region of the spool. These cracks form from metallurgical anomalies
that result from reduced forging work associated with the sixteen inch
billet material used in the manufacture of certain HPCR stage 3-9
spools.
Based on the investigation findings, and the higher than projected
crack occurrence rates, the FAA has determined that the inspection
schedule in the current AD should be accelerated, and a repetitive
inspection requirement be implemented.
The FAA has reviewed and approved the technical contents of GE CF6-
50 Service Bulletin (SB) No. 72-1000, Revision 2, dated September 9,
1993, and GE CF6-80A SB No. 72-583, Revision 4, dated September 15,
1993, which describe procedures for the ultrasonic and eddy current
inspection of the HPCR stage 3-9 spool.
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 91-20-01, would retain the one-time
ultrasonic and eddy current inspection of the HPCR stage 3-9 spool for
cracks as required in the current AD, but would accelerate the
inspection schedule, and introduce a repetitive ultrasonic and eddy
current inspection requirement.
There are approximately 462 GE CF6-45/-50/-80A series engines of
the affected design in the worldwide fleet. The FAA estimates that 67
engines installed in aircraft of U.S. registry would be affected by the
proposed AD, that it would take approximately 584 work hours per engine
to accomplish the proposed actions, and that the average labor rate is
$55 per work hour. Required parts would cost approximately $127,412 per
engine. Based on these figures, and assuming that 3 of the inspected
spools will require replacement, the total cost impact of the proposed
AD on U.S. operators is estimated to be $2,534,276.
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 ``major rule'' under Executive Order 12291;
(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 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 removing Amendment 39-8035 (56 FR
55230; October 25, 1991) and by adding a new airworthiness directive to
read as follows:
General Electric Company: Docket No. 94-ANE-11. Supersedes AD 91-20-
01, Amendment 39-8035.
Applicability: General Electric Company (GE) CF6-45/-50/-80A
series turbofan engines installed on, but not limited to, Airbus
A300 and A310 series, Boeing 747 and 767 series, and McDonnell
Douglas DC-10 series aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent an uncontained high pressure compressor rotor (HPCR)
stage 3-9 spool failure, which could result in damage to the
aircraft, accomplish the following:
(a) Eddy current and ultrasonic inspect GE CF6-45/-50 HPCR stage
3-9 spools, Part Number (P/N) 9136M89G02, 9136M89G03, 9136M89G06,
9136M89G08, 9253M85G01, 9253M85G02, 9273M14G01, and 9331M29G01, with
serial numbers (S/N) listed in Table 2 of GE CF6-50 Service Bulletin
(SB) No. 72-1000, Revision 2, dated September 9, 1993, as follows:
(1) For spools that have not been previously inspected in
accordance with GE CF6-50 SB No. 72-888, Original, Revision 1,
Revision 2, Revision 3, or Revision 4, or GE CF6-50 SB No. 72-1000,
Original, Revision 1, or Revision 2, inspect in accordance with
paragraph 2.C of GE CF6-50 SB No. 72-1000, Revision 2, dated
September 9, 1993, at the next engine shop visit, or by 30 days
after the effective date of this AD, whichever occurs earlier.
(2) For spools that have been inspected in accordance with GE
CF6-50 SB No. 72-888, Original, Revision 1, or Revision 2, inspect
in accordance with paragraph 2.D of GE CF6-50 SB No. 72-1000,
Revision 2, dated September 9, 1993, at the next engine shop visit,
or by December 31, 1994, whichever occurs earlier.
(3) For spools that have been inspected in accordance with GE
CF6-50 SB No. 72-888, Original, Revision 1, or Revision 2, and GE
CF6-50 SB No. 72-1008, Original, inspect in accordance with
paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated
September 9, 1993, at the next piece-part exposure, or within 3,500
cycles in service (CIS) since inspected in accordance with GE CF6-50
SB No. 72-1008, Original, whichever occurs earlier.
(4) For spools that have been inspected in accordance with GE
CF6-50 SB No. 72-888, Revision 3, or Revision 4, or GE CF6-50 SB No.
72-1000, Original, Revision 1, or Revision 2, inspect in accordance
with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated
September 9, 1993, at the next piece-part exposure, or within 3,500
CIS since inspected in accordance with, GE CF6-50 SB No. 72-888,
Revision 3, or Revision 4, or GE CF6-50 SB No. 72-1000, Original,
Revision 1, or Revision 2, whichever occurs earlier.
(b) Thereafter, for spools that have been inspected in
accordance with paragraph (a) of this AD, reinspect in accordance
with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated
September 9, 1993, at intervals not to exceed 3,500 CIS since the
last inspection.
(c) Eddy current and ultrasonic inspect GE CF6-80A HPCR 3-9
spool, P/N 9136M89G10, with S/N's listed in Table 2 of GE CF6-80A SB
No. 72-583, Revision 4, dated September 15, 1993, as follows:
(1) For spools that have not been previously inspected in
accordance with GE CF6-80A SB No. 72-500, Original, Revision 1,
Revision 2, Revision 3, or Revision 4, or GE CF6-80A SB No. 72-583,
Original, Revision 1, Revision 2, Revision 3, or Revision 4, inspect
in accordance with paragraph 2.C of GE CF6-80A SB No. 72-583,
Revision 4, dated September 15, 1993, at the next engine shop visit,
or by 30 days after the effective date of this AD, whichever occurs
earlier.
(2) For spools that have been previously inspected in accordance
with GE CF6-80A SB No. 72-500, Revision 3, or Revision 4, or GE CF6-
80A SB No. 72-583, Original, Revision 1, Revision 2, Revision 3, or
Revision 4, inspect in accordance with paragraph 2.D of GE CF6-80A
SB No. 72-583, Revision 4, dated September 15, 1993, at the next
piece-part exposure, or within 3,500 CIS since inspected in
accordance with GE CF6-80A SB No. 72-500, Revision 3, or Revision 4,
or GE CF6-80A SB No. 72-583, Original, Revision 1, Revision 2,
Revision 3, or Revision 4, whichever occurs earlier.
(d) Thereafter, for spools that have been inspected in
accordance with paragraph (c) of this AD, reinspect in accordance
with paragraph 2.D of GE CF6-80A SB No. 72-583, Revision 4, dated
September 15, 1993, at intervals not to exceed 3,500 CIS since the
last inspection.
(e) Remove from service prior to further flight HPCR stage 3-9
spools that meet or exceed the reject criteria established in
Section 2.C and 2.D, as applicable, of GE CF6-50 SB No. 72-1000,
Revision 2, dated September 9, 1993, and GE CF6-80A SB No. 72-583,
Revision 4, dated September 15, 1993, as appropriate.
(f) 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.
(g) For the purpose of this AD, piece-part exposure is defined
as disassembly and removal of the stage 3-9 spool from the HPCR
rotor.
(h) An alternative method of compliance or adjustment of the
compliance time, which provides an acceptable level of safety, may
be used when 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.
(i) 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.
Issued in Burlington, Massachusetts, on April 26, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-10503 Filed 5-2-94; 8:45 am]
BILLING CODE 4910-13-P
