Airworthiness Directives; General Electric Company CF6-50 Series Turbofan Engines

[Federal Register Volume 66, Number 44 (Tuesday, March 6, 2001)]
[Rules and Regulations]
[Pages 13418-13422]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-4939]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-38-AD; Amendment 39-12136; AD 2001-04-16]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-50 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to General Electric Company (GE) CF6-50 series 
turbofan engines. That AD currently requires visual inspection of the 
stage 2 low pressure turbine (LPT) nozzle lock assemblies, and 
replacement of the borescope plug with a new design plug.
    This amendment is prompted by a report of an uncontained engine 
failure on an engine that had complied with the current AD. This 
amendment requires additional inspections and provides interim and 
terminating corrective actions. The actions specified in this AD are 
intended to detect cracked, loose or missing stage 2 LPT nozzle lock 
assembly studs that could lead to failure of the locks, nozzle segment 
rotation, LPT case machining, and subsequent uncontained failure of the 
engine. The actions also provide for modifications of nozzle lock 
assemblies if the nozzle lock studs are found cracked, loose, or 
missing.

DATES: Effective March 21, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 21, 2001.
    Comments for inclusion in the Rules Docket must be received on or 
before May 7, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel,

[[Page 13419]]

Attention: Rules Docket No. 2000-NE-38-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. The service information referenced in this AD may be 
obtained from General Electric Company via Lockheed Martin Technology 
Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 45215, 
telephone (513) 672-8400, fax (513) 672-8422. 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.

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: On September 21, 2000, the FAA issued AD 
2000-20-02, Amendment 39-11913 (65 FR 58645, October 2, 2000) to 
require visual inspection of the stage 2 LPT nozzle lock studs, and 
replacement of the borescope plug with a new design plug. That action 
was prompted by three uncontained engine failures resulting from stage 
2 LPT lock stud failures, nozzle segment rotation, and LPT case 
machining. That condition, if not corrected, could result in failure of 
the stage 2 LPT nozzle lock assemblies. Since AD 2000-20-02 was issued, 
there has been one more uncontained engine failure, on February 4, 
2001, that has been attributed to the failure of stage 2 Waspalloy LPT 
nozzle lock assembly studs. That engine is reported to have been in 
compliance with AD 2000-20-02, at the time of failure. Because of this 
report, and because of the recent issuance of three GE service 
bulletins (SB's), two of which are alert service bulletins (ASB's), the 
FAA has determined that it is necessary to supersede AD 2000-20-02. The 
GE SB's provide for
    <bullet> Stage 2 Waspalloy LPT nozzle lock ultrasonic inspection 
(previously allowed as an alternative method of compliance (AMOC) to AD 
2000-20-02),
    <bullet> LPT case modification and new nozzle lock incorporation 
(previously allowed as an AMOC to AD 2000-20-02), and,
    <bullet> Stage 2 LPT additional nozzle lock incorporation.
    The methods for complying with AD 2000-20-02 that were previously 
approved as AMOCS to that AD have been incorporated into this AD.
    This AD incorporates by reference, one SB and one ASB as-written. 
This AD also incorporates by reference another inspection ASB, but with 
two exceptions. Because of the recent engine failure, the inspection 
ASB is incorporated with a reduction in the stage 2 LPT Waspalloy 
nozzle lock ultrasonic inspection thresholds, but does not include the 
requirement to inspect the stages 3 and 4 LPT nozzle locks.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of the 
following:
    <bullet> GE ASB CF6-50 72-A1197, dated December 14, 2000, that 
describes procedures for on-wing or off-wing initial and repetitive 
ultrasonic inspections of stage 2 LPT Waspalloy nozzle lock studs for 
cracks. This ASB also defines initial and repetitive visual inspections 
of stage 2 LPT Rene nozzle lock studs.
    <bullet> GE ASB CF6-50 72-A1201, dated December 22, 2000, and CF6-
50 72-A1201, Revision 1, dated February 6, 2001, describe procedures 
for LPT case modification and incorporation of new design nozzle locks. 
Accomplishment of this ASB constitutes terminating action for the 
inspection requirements of this AD.
    <bullet> GE SB CF6-50 72-1203, dated November 22, 2000, and CF6-50 
72-1203 Revision 1, dated February 7, 2001, describe procedures for 
incorporating additional stage 2 LPT nozzle locks when an engine is 
found to have a reject condition as described in GE ASB CF6-50 72-
A1197, dated December 14, 2000, and the required compliance cannot be 
addressed by an immediate shop visit.

Differences Between the Manufacturer's Service Information and This 
AD

    Although GE ASB CF6-50 72-A1197, dated December 14, 2000, requires 
ultrasonic inspections of stage 2 LPT Waspalloy nozzle lock studs to be 
done at specified times, the FAA has determined that more stringent 
initial and repetitive ultrasonic inspection time intervals are 
required to meet the necessary level of safety, and have incorporated 
those intervals in this amendment. Also, although that ASB requires the 
stages 3 and 4 LPT nozzle locks to be inspected, the FAA has determined 
that an unsafe condition is not likely to occur as a result of a stage 
3 or 4 lock stud failure and therefore this AD requires only the stage 
2 LPT nozzle locks to be inspected.

Actions Required by This AD

    Since an unsafe condition has been identified that is likely to 
exist or develop on other GE CF6-50 series turbofan engines of the same 
type design, this AD supersedes AD 2000-20-02 to require:
    <bullet> Installation of the solid borescope plug for engines that 
have not already complied with paragraph (e) of AD 2000-20-02.
    <bullet> On-wing or off-wing initial and repetitive ultrasonic 
inspections of stage 2 Waspalloy LPT nozzle lock assembly studs for 
cracks.
    <bullet> On-wing or off-wing initial and repetitive visual 
inspections of stage 2 LPT nozzle lock assembly studs for loose or 
missing studs.
    <bullet> Replacement of all of the stage 2 LPT lock assemblies with 
new design assemblies before further flight if a cracked, loose, or 
missing stud is found, OR,
    <bullet> Incorporation of additional stage 2 LPT nozzle locks if no 
indications of nozzle rotation are found, as an interim action to allow 
time to arrange for a shop visit, within 3,500 cycles-in-service.
    <bullet> Inspection of the area surrounding the borescope plug for 
evidence of buckling or cracks whenever the nozzle lock studs are 
inspected.
    <bullet> Inspection for loose or missing added nozzle locks and LPT 
case cracking in the areas of the added nozzle locks, every 750 hours 
time-in-service.
    <bullet> Replacement of the LPT lock assemblies with new design 
assemblies before further flight if any LPT case buckling or cracks are 
found, or if nozzle segment rotation is found.

Immediate Adoption of This AD

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Received

    Interested persons were afforded an opportunity to participate in 
the making of Amendment 39-11913. Due consideration has been given to 
the comments received.

Change Inspection Thresholds and Intervals

    One commenter requests that the inspection thresholds and intervals 
be changed to coincide with scheduled

[[Page 13420]]

aircraft ``A-Check'' intervals, or the manufacturer's recommended 
engine repetitive maintenance intervals.
    The FAA disagrees. As the commenter stated in their request, the 
``A-Check'' interval can vary from operator to operator. ``A-Check'' 
intervals as low as 200 hours to as high as 700 hours have been 
reported. To provide an equivalent level of safety for all operators, 
the inspection thresholds and intervals must therefore be defined in 
this AD.

Extend 30 Day Compliance Requirement for Borescope Plug Replacement

    One commenter requests that the 30 day compliance requirement for 
the borescope plug installation be extended to 90 days or next ``A-
Check'', due to limited parts availability.
    The FAA disagrees. The manufacturer provided evidence that 
sufficient parts had been procured and distributed to support the 30 
day requirement.

Editorial Correction

    One commenter requests that the word ``place'' in paragraph (d) of 
AD 2000-20-02 be changed to read ``replace''.
    The FAA agrees. A correction was published in the Federal Register 
on October 16, 2000 (65 FR 61216).

Comments on New Amendment Invited

    Although this superseding amendment is in the form of a final rule 
that involves requirements affecting flight safety and, thus, was not 
preceded by notice and an opportunity for public comment, comments are 
invited on this rule. Interested persons are invited to comment on this 
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 under the caption 
ADDRESSES. All communications received on or before the closing date 
for comments will be considered, and this rule may be amended in light 
of the comments received. Factual information that supports the 
commenter's ideas and suggestions is extremely helpful in evaluating 
the effectiveness of the AD action and determining whether additional 
rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000NE-38-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    This final rule does not have federalism implications, as defined 
in Executive Order No. 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 rule.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, 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 part 39 of 
Title 14 of the Code of Federal 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 39-11913 (65 FR 
58645, October 2, 2000), and by adding a new airworthiness directive 
(AD), Amendment 39-12136, to read as follows:

2001-04-16  General Electric Company: Amendment 39-12136. Docket No. 
2000-NE-38-AD. Supersedes AD 2000-20-02, Amendment 39-11913.

    Applicability. This airworthiness directive (AD) is applicable 
to General Electric Company (GE) CF6-50 series turbofan engines. 
These engines are installed on, but not limited to, Airbus 
Industries A300, Boeing Airplane Company 747, and McDonnell Douglas 
Corporation DC10 airplanes.

    Note 1: 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 request approval for an 
alternative method of compliance in accordance with paragraph (l) 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. Compliance with this AD is required as indicated, 
unless already done.
    To detect cracked, loose, or missing stage 2 low pressure 
turbine (LPT) nozzle lock assembly studs that could lead to failure 
of the locks, segment rotation, LPT case machining, and subsequent 
uncontained failure of the engine, do the following:

Installation of Solid Borescope Plug

    (a) For engines that have not already complied with paragraph 
(e) of AD 2000-20-02, install a stage 2 LPT solid borescope 
inspection plug part number (P/N) 2083M99P01, or a plug with the 
alternate P/N's 305-381-303-0 or 2110M79P01, before further flight, 
unless paragraph (e)(1) (GE Alert Service Bulletin (ASB) CF6-50 72-
A1201, or CF6-50 72-A1201, Revision 1) of this AD has already been 
accomplished.

Visual Inspection of Stage 2 Nozzle Lock Assemblies

    (b) For engines with stage 2 LPT Rene 41 nozzle lock assemblies, 
visually inspect locks for loose or missing studs, in accordance 
with Paragraph 3.B., Accomplishment Instructions of GE ASB CF6-50 
72-A1197, dated December 14, 2000, within the following times:

[[Page 13421]]



            Table 1.--Rene 41 Stage 2 Nozzle Lock Assemblies
------------------------------------------------------------------------
                                                      Repetitive inspect
  Time on Rene 41 lock assembly     Inspect within          within
------------------------------------------------------------------------
(1) Less than 4,000 hours time-   750 hours after     750 hours time-
 since-new (TSN) on the            accumulating        since-last
 effective date of this AD.        4,000 hours TSN.    inspection
                                                       (TSLI).
(2) 4,000 hours TSN or greater,   750 hours TIS       750 hours TSLI.
 or if TSN is not known, on the    after the
 effective date of this AD.        effective date of
                                   this AD.
------------------------------------------------------------------------

    (c) For engines with stage 2 LPT Waspalloy nozzle lock 
assemblies, visually inspect for loose or missing studs within the 
following times:

            Table 2.--Waspalloy Stage 2 Nozzle Lock Assemblies
------------------------------------------------------------------------
 Time on Stage 2 Waspalloy lock     Initial inspect   Repetitive inspect
            assembly                    within              within
------------------------------------------------------------------------
(1) Less than 1,250 hours TSN on  750 hours after     750 hours TSLI.
 the effective date of this AD.    accumulating
                                   1,250 hours TSN.
(2) Greater than or equal to      750 hours TIS       750 hours TSLI.
 1,250 hours TSN, but less than    after the
 4,000 hours TSN on the            effective date of
 effective date of this AD.        this AD.
(3) 4,000 hours TSN or greater,   250 hours TIS       750 hours TSLI.
 on the effective date of this     after the
 AD, or, if hours unknown.         effective date of
                                   this AD.
------------------------------------------------------------------------

Ultrasonic Inspection of Stage 2 LPT Waspalloy Nozzle Lock Assemblies

    (d) For engines with stage 2 LPT Waspalloy nozzle lock 
assemblies with no loose or missing studs found in accordance with 
paragraph (c) of this AD, ultrasonically inspect studs for cracks in 
accordance with Paragraph 3.A., Accomplishment Instructions of GE 
ASB CF6-50 72-A1197, dated December 14, 2000, within the times 
identified in paragraph (c) of this AD.

Corrective Action

    (e) For engines with either stage 2 LPT Rene 41 or Waspalloy 
nozzle lock assemblies where the assembly studs are found loose or 
missing, do one of the following:
    (1) Prior to further flight, modify the LPT case and install new 
design nozzle locks as specified in GE ASB CF6--50 72-A1201, dated 
December 22, 2000, or CF6--50 72-A1201, Revision 1, dated February 
6, 2001; or
    (2) Prior to further flight, as an interim on-wing action for 
stage 2 LPT nozzle locks only, modify the LPT case and install seven 
additional nozzle locks as specified in GE service bulletin CF6-50 
72-1203, dated November 22, 2000, or CF6-50 72-1203, Revision 1, 
dated February 7, 2001, providing the following conditions are met 
prior to modification:
    (i) There are no cracks or distortion in the stage 2 borescope 
plug area of the LPT case.
    (ii) The borescope plug is able to be removed.
    (iii) There is no evidence of stage 2 nozzle segment rotation, 
as evidenced by a borescope inspection that reveals that no nozzle 
segment circumferential gap is greater than 0.250 inch.
    (f) For engines with stage 2 LPT nozzle lock assemblies modified 
in accordance with paragraph (e)(2) of this AD, perform the 
following inspections every 750 hours TIS, until the engine is 
modified in accordance with paragraph (e)(1) of this AD:
    (1) Repetitive visual inspections of the seven additional nozzle 
locks for loose or missing locks.
    (2) Repetitive visual inspections of the LPT case in the area of 
the additional locks for cracks.
    (3) Repetitive visual inspections of the LPT case in the area of 
the borescope plug for cracks.

    Note 2: Modification of the LPT case and installation of the 
additional locks per paragraph (e)(2) of this AD should not be 
performed by the same individual for all engines installed on the 
same airplane prior to the same flight.

    (g) Engines rejected by the inspections in paragraph (f) of this 
AD are not serviceable and must be modified in accordance with 
paragraph (e)(1) of this AD prior to further flight.
    (h) Modification of the LPT case in accordance with paragraph 
(e)(2) of this AD establishes a life limit for LPT case P/N's 
2083M38G01, 2083M38G02, 2083M38G03, 2083M38G04, 2083M38G05, 
2083M38G06, 2083M38G07, and 2083M38G08, of 3,500 CIS since 
modification.
    (i) Except as required in paragraph (j) of this AD, for engines 
with stage 2 LPT Waspalloy nozzle lock assemblies where one or more 
studs are found cracked by the inspections in paragraph (d) of this 
AD, but where no two cracked studs are located adjacent to each 
other, continued operation for an additional 25 hours time-in-
service, maximum, is allowed prior to performing one of the 
corrective actions in paragraph (e) of this AD.
    (j) For engines with two or more adjacent stage 2 LPT Waspalloy 
nozzle lock studs found cracked by the inspections in paragraph (d) 
of this AD, do one of the corrective actions in paragraph (e) of 
this AD prior to further flight.

    Note 3: After installation of new design nozzle locks in 
accordance with paragraph (e)(1) of this AD, any solid borescope 
plug may be replaced with the standard borescope plug if the 
operator so chooses.

Terminating Action

    (k) Accomplishment of Paragraphs 3.A. through 3.E.(2) of GE ASB 
CF6-50 72-A1201, dated December 22, 2000, or CF6-50 72-A1201, 
Revision 1, dated February 6, 2001 (modification of the LPT case and 
installation of new design nozzle locks per paragraph (e)(1) of this 
AD), is terminating action for the inspection requirements of this 
AD.

Alternative Methods of Inspection

    (l) 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 requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Special Flight Permits

    (m) Special flight permits may be issued in accordance with 
sections 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.

Incorporation by Reference Material

    (n) The actions required by this AD shall be done in accordance 
with the following General Electric Co. alert service bulletins 
(ASB) and service bulletin (SB):

[[Page 13422]]



----------------------------------------------------------------------------------------------------------------
              Document                  Pages               Revision                          Date
----------------------------------------------------------------------------------------------------------------
ASB CF6-50 72-A1197................         1-28  Original...................  December, 14, 2000.
  Total pages: 28
 
ASB CF6-50 72-A1201................         1-21  Original...................  December 22, 2000.
  Total pages: 21
 
ASB CF6-50 72-A1201................         1-22  1..........................  February 6, 2001.
  Total pages: 22
 
SB CF6-50 72-1203..................          1-9  Original...................  November 22, 2000.
  Total pages: 9
 
SB CF6-50 72-1203..................         1-12  1..........................  February 7, 2001.
  Total pages: 12
----------------------------------------------------------------------------------------------------------------

The incorporations by reference were 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 Company via 
Lockheed Martin Technology Services, 10525 Chester Road, Suite C, 
Cincinnati, Ohio 45215, telephone (513) 672-8400, fax (513) 672-
8422. Copies may be inspected 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.

Effective Date

    (o) This amendment becomes effective on March 21, 2001.


    Issued in Burlington, Massachusetts, on February 23, 2001.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 01-4939 Filed 3-5-01; 8:45 am]
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