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

[Federal Register Volume 65, Number 191 (Monday, October 2, 2000)]
[Rules and Regulations]
[Pages 58645-58647]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24901]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-38-AD; Amendment 39-11913; AD 2000-20-02]
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 adopts a new airworthiness directive (AD) that 
is applicable to General Electric Company (GE) CF6-50 series turbofan 
engines. This action requires inspection of the low pressure turbine 
nozzle lock assemblies, and replacement of the borescope plug with a 
new design plug. This amendment is prompted by three uncontained engine 
failures. The actions specified in this AD are intended to detect loose 
or missing LPT nozzle lock assembly studs that could lead to failure of 
the locks and subsequent uncontained failure of the engine.

DATES: Effective October 17, 2000. The incorporation by reference of 
certain publications listed in the rule is approved by the Director of 
the Federal Register as of October 17, 2000.
    Comments for inclusion in the Rules Docket must be received on or 
before December 1, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, 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 April 25, 2000, a DC10-30 experienced an 
uncontained engine failure during takeoff. Ground inspection found 
uncontainment of the low pressure turbine (LPT) case, airplane damage, 
and ingestion damage to the other two engines. An investigation 
revealed that the failure of stage 2 LPT nozzle lock assemblies made of 
Waspalloy material resulted in the uncontained failure of all stage 2 
nozzle segments.
    Since that time, there have been two more uncontained engine 
failures, on September 5, 2000, and September 7, 2000, that have been 
attributed to the failure of Waspalloy stage 2 LPT nozzle lock assembly 
studs.
    Before these three events, there had been two uncontained failures 
of stage 2 LPT nozzle lock assemblies made of Rene 41 material. One 
failure was in April 1991 which was contained within the cowl with no 
damage to the airplane, and one in 1996 that also penetrated the cowl 
and resulted in minor damage to the airplane. There was also one 
unscheduled engine removal (UER) for broken Rene 41 nozzle lock 
assembly studs in 1997 and two UER's for broken Waspalloy assemblies; 
one in January 1999, and one in December 1999.
    Loose or missing LPT nozzle lock assembly studs could lead to 
failure of the locks and subsequent uncontained failure of the engine.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of GE 
Alert Service Bulletin (ASB) CF6-50 72-A1196, dated September 15, 2000, 
that describes procedures for replacing the existing stage 2 LPT nozzle 
borescope plug, part number (P/N) 9022M63G13, with borescope plug P/N 
2083M99P01. This new plug provides an additional antirotation feature 
for the nozzle segments in the event of failure of the nozzle locks.

Interim Action Requirements of 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 is being issued as an interim action to detect 
loose or missing LPT nozzle lock assembly studs that could lead to 
failure of the lock assemblies, and subsequent uncontained failure of 
the engine. This AD requires:
    <bullet> Initial and repetitive inspections of the lock assemblies 
for loose or missing studs.
    <bullet> Replacement of all of the stage 2 LPT lock assemblies with 
new assemblies before further flight if a loose or missing stud is 
found.
    <bullet> Installation of borescope plug P/N 2083M99P01. This new 
borescope plug is designed to prevent rotation of the stage 2 LPT 
nozzle if the nozzle lock assemblies fail.
    <bullet> Inspection of the area surrounding the borescope plug for 
evidence of buckling or cracks whenever the nozzle lock studs are 
inspected.
    <bullet> Replacement of the LPT stator case assembly with a 
serviceable part before further flight if any buckling or cracks are 
found.
    The borescope plug must be replaced as specified in ASB CF6-50 72-
A1196.

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 Invited

    Although this action 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

[[Page 58646]]

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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NE-38-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    This proposed 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 proposed 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 adding the following new 
airworthiness directive:

2000-20-02  General Electric Company: Amendment 39-11913. Docket 
2000-NE-38-AD.

    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 (h) 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 loose or missing LPT nozzle lock assembly studs that 
could lead to failure of the locks and subsequent uncontained 
failure of the engine, do the following:

Initial Inspection of Stage 2 LPT Nozzle Lock Assemblies

    (a) Visually inspect the stage 2 LPT nozzle lock assemblies for 
loose or missing studs within the following times after the 
effective date of this AD information about on-wing visual 
inspections may be found in the appropriate aircraft maintenance 
manual (AMM):

------------------------------------------------------------------------
                                             Inspect within the earlier
          Time on lock  assembly                         of
------------------------------------------------------------------------
(1) 5,500 or fewer hours time-since-new     500 hours time-in-service
 (TSN) on the effective date of this AD.     (TIS) or 60 days after the
                                             effective date of this AD.
(2) Greater than 5,500 hours TSN on the     250 hours TIS or 30 days
 effective date of this AD, or if TSN is     after the effective date of
 not known.                                  this AD.
------------------------------------------------------------------------

    (b) If any stage 2 LPT nozzle lock assembly stud is loose or 
missing, replace all of the stage 2 LPT nozzle lock assemblies with 
new nozzle lock assemblies before the further flight.

Repetitive Inspection of Stage 2 LPT Nozzle Lock Assemblies

    (c) Thereafter, visually inspect the stage 2 LPT nozzle lock 
assemblies for loose or missing studs within the following times-
since-last-inspection (TSLI) information about on-wing visual 
inspections may be found in the appropriate AMM:

------------------------------------------------------------------------
          Time on lock  assembly                Repetitive inspection
------------------------------------------------------------------------
(1) 5,500 or fewer hours TSN..............  500 hours TSLI.
(2) Greater than 5,500 hours TSN or if TSN  250 hours TSLI.
 is not known.
------------------------------------------------------------------------

    (d) If any stage 2 LPT nozzle lock assembly stud is loose or 
missing, place all of the stage 2 LPT nozzle lock assemblies with 
new nozzle lock assemblies before further flight.

Replacement of Borescope Plug

    (e) On engines with lock assemblies that have the following 
times on the effective date of this AD, remove the existing stage 2 
LPT nozzle borescope plug, part number P/N 9022M63G13, and install 
borescope plug P/N 2083M99P01, or a plug with the alternate P/N's 
305-381-303-0 or 2110M79P01, in accordance with the Accomplishment 
Instructions 3.A through 3.B.(7) of GE alert service bulletin (ASB) 
CF6-50 72-A1196, dated September 15, 2000:

------------------------------------------------------------------------
                                               Install borescope plug
          Time on lock  assembly                within the earlier of
------------------------------------------------------------------------
(1) 5,500 or fewer hours TSN on the         500 hours TIS or 60 days
 effective date of this AD.                  after the effective date of
                                             this AD.
(2) Greater than 5,500 hours TSN on the     250 hours TIS or 30 days
 effective date of this AD.                  after the effective date of
                                             this AD.
------------------------------------------------------------------------

    (f) Do not install borescope plug P/N 9022M63G13 in the 
borescope inspection port for the stage 2 LPT nozzle after the plug 
has been replaced in accordance with paragraph (e) of this AD.

Inspection for Buckling and Cracks

    (g) For engines on which the borescope plug has been replaced in 
accordance with paragraph (e) of this AD, visually inspect the LPT 
stator case assembly around the stage 2 LPT borescope inspection 
port boss each time the lock assemblies are inspected, as specified 
in paragraph (c) of this AD, for evidence of buckling or cracks. If 
buckling or cracks are found, replace the LPT stator case assembly 
before further flight with a serviceable case.

Alternative Methods of Inspection

    (h) An alternative method of compliance of 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

[[Page 58647]]

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

    Note 2: 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

    (i) Special flights 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.

Documents That Have Been Incorporated by Reference

    (j) The borescope plug replacement must be done in accordance 
with GE ASB CF6-50 72C-A1196, dated September 15, 2000. 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 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

    (k) This amendment becomes effective on October 17, 2000.

    Issued in Burlington, Massachusetts, on September 21, 2000.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-24901 Filed 9-29-00; 8:45 am]
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