Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

[Federal Register Volume 76, Number 24 (Friday, February 4, 2011)]
[Rules and Regulations]
[Pages 6323-6326]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-2387]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0068; Directorate Identifier 2010-NE-05-AD; 
Amendment 39-16580; AD 2011-02-07]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-45 and 
CF6-50 Series Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: We are superseding an existing airworthiness directive (AD) 
for General Electric Company (GE) CF6-45 and CF6-50 series turbofan 
engines with certain low-pressure turbine (LPT) rotor stage 3 disks 
installed. That AD currently requires initial and repetitive borescope 
inspections of the high-pressure turbine (HPT) rotor stage 1 and stage 
2 blades for wear and damage, including excessive airfoil material 
loss. That AD also requires fluorescent-penetrant inspection (FPI) of 
the LPT rotor stage 3 disk under certain conditions and removal of the 
disk from service before further flight if found cracked. That AD also 
requires repetitive exhaust gas temperature (EGT) system checks 
(inspections). This AD requires HPT rotor stage 1 and stage 2 blade 
inspections and EGT system inspections. This AD also requires FPI of 
the LPT rotor stage 3 disk under certain conditions, removal of the 
disk from service before further flight if found cracked, and an 
ultrasonic inspection (UI) of the LPT rotor stage 3 disk forward spacer 
arm. This AD also requires initial and repetitive engine core vibration 
surveys and reporting to the FAA any crack findings, disks that fail 
the UI, and engines that fail the engine core vibration survey.
    This AD was prompted by reports received of additional causes of 
HPT rotor imbalance not addressed in AD 2010-12-10, and two additional 
LPT rotor stage 3 disk events. We are issuing this AD to prevent 
critical life-limited rotating engine part failure, which could result 
in an uncontained engine failure and damage to the airplane.

DATES: This AD is effective February 22, 2011.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of February 22, 
2011.
    We must receive any comments on this AD by March 21, 2011.

ADDRESSES: You may send comments by any of the following methods:
    <bullet> Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
    <bullet> Fax: 202-493-2251.
    <bullet> Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
    <bullet> Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The street address for 
the Docket Office (phone: 800-647-5527) is in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Tomasz Rakowski, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; phone: 781-238-7735; 
fax: 781-238-7199; e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    On June 4, 2010, we issued AD 2010-12-10, Amendment 39-16331 (75 FR 
32649, June 9, 2010), for CF6-45 and CF6-50 series turbofan engines 
with certain LPT rotor stage 3 disks installed. That AD requires 
initial and repetitive borescope inspections of the HPT rotor stage 1 
and stage 2 blades for wear and damage, including excessive airfoil 
material loss. That AD also requires FPI of the LPT rotor stage 3 disk 
under certain conditions, removal of the disk from service before 
further flight if found cracked, and repetitive EGT system checks 
(inspections). That AD resulted from reports received of two additional 
LPT rotor stage 3 disk events since the original AD 2010-06-15, 
Amendment 39-16240 (75 FR 12661, March 17, 2010) was issued. We issued 
those ADs to prevent critical life-limited rotating engine part 
failure, which could result in an uncontained engine failure and damage 
to the airplane.

[[Page 6324]]

Actions Since AD was Issued

    Since we issued AD 2010-12-10, investigations have revealed 
additional causes for HPT rotor imbalance not addressed in that AD, and 
two additional LPT rotor stage 3 disk events have occurred.

FAA's Determination

    We are issuing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

AD Requirements

    This AD requires:
    <bullet> HPT rotor stage 1 and stage 2 blade inspections and EGT 
system inspections; and
    <bullet> FPI of the LPT rotor stage 3 disk under certain conditions 
and removal of the disk from service before further flight if found 
cracked; and
    <bullet> A UI of the LPT rotor stage 3 disk forward spacer arm; and
    <bullet> Initial and repetitive engine core vibration surveys; and
    <bullet> Reporting to the FAA any crack findings, disks that fail 
the UI, and engines that fail the engine core vibration survey.

FAA's Justification and Determination of the Effective Date

    An unsafe condition exists that requires the immediate adoption of 
this AD. The FAA has found that the risk to the flying public justifies 
waiving notice and comment prior to adoption of this rule because we 
require near immediate corrective action to address the unsafe 
condition. Therefore, we find that notice and opportunity for prior 
public comment are impracticable, and that good cause exists for making 
this amendment effective in less than 30 days.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety, and we did not provide you with notice and an opportunity to 
provide your comments before it becomes effective. However, we invite 
you to send any written data, views, or arguments about this AD. Send 
your comments to an address listed under the ADDRESSES section. Include 
the docket number FAA-2010-0068 and directorate identifier 2010-NE-05-
AD at the beginning of your comments. We specifically invite comments 
on the overall regulatory, economic, environmental, and energy aspects 
of this AD. We will consider all comments received by the closing date 
and may amend this AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this AD.

Costs of Compliance

    We estimate that this AD will affect 387 CF6-45 and CF6-50 series 
turbofan engines installed on airplanes of U.S. registry. We also 
estimate that it will take, about 8 hours to perform the HPT blade 
inspection, 6 hours to perform a vibration survey, 4 hours to perform 
an ultrasonic inspection, 2 hours to perform an EGT resistance check, 
and 1 hour to perform an EGT thermocouple inspection for each engine. 
The average labor rate is $85 per work-hour. We anticipate no required 
parts cost. Based on these figures, we estimate the total cost of the 
AD to U.S. operators to be $690,795.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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.
    For the reasons discussed above, I certify that this AD:
    (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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends part 39 of the Federal Aviation 
Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by removing airworthiness directive (AD) 
2010-12-10, Amendment 39-16331 (75 FR 32649, June 9, 2010) and adding 
the following new AD:

2011-02-07 General Electric Company: Amendment 39-16580; Docket No. 
FAA-2010-0068; Directorate Identifier 2010-NE-05-AD.

Effective Date

    (a) This AD is effective February 22, 2011.

Affected ADs

    (b) This AD supersedes AD 2010-12-10, Amendment 39-16331.

Applicability

    (c) This AD applies to the following engines with any of the 
low-pressure turbine (LPT) rotor stage 3 disk part numbers listed in 
Table 1 of this AD installed in:
    (1) General Electric Company (GE) CF6-45A, CF6-45A2, CF6-50A, 
CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-
50E, CF6-50E1, and CF6-50E2 turbofan engines, including engines 
marked on the engine data plate as CF6-50C2-F and CF6-50C2-R.
    (2) These engines are installed on, but not limited to, Airbus 
A300 series, Boeing 747 series, McDonnell Douglas DC-10 series, and 
DC-10-30F (KDC-10) airplanes.

[[Page 6325]]



                                                 Table 1--Applicable LPT Rotor Stage 3 Disk Part Numbers
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                9061M23P06                     9061M23P07                     9061M23P08                     9061M23P09                    9224M75P01
                9061M23P10                     1473M90P01                     1473M90P02                     1473M90P03                    1473M90P04
                9061M23P12                     9061M23P14                     9061M23P15                     9061M23P16                    1479M75P01
                1479M75P02                     1479M75P03                     1479M75P04                     1479M75P05                    1479M75P06
                1479M75P07                     1479M75P08                     1479M75P09                     1479M75P11                    1479M75P13
                1479M75P14                            N/A                            N/A                            N/A                           N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from reports received of additional causes 
of high-pressure turbine (HPT) rotor imbalance not addressed in AD 
2010-12-10, and two additional LPT rotor stage 3 disk events. We are 
issuing this AD to prevent critical life-limited rotating engine 
part failure, which could result in an uncontained engine failure 
and damage to the airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Borescope Inspections of HPT Rotor Stage 1 and Stage 2 Blades

    (f) For the borescope inspections required by paragraphs (f)(1), 
(f)(2), and (f)(3) of this AD, inspect the blades from the forward 
and aft directions. Inspect all areas of the blade airfoil: Your 
inspection must include blade leading and trailing edges, and their 
convex and concave airfoil surfaces. Inspect for signs of impact, 
cracking, burning, damage, or distress.
    (1) Perform an initial borescope inspection of the HPT rotor 
stage 1 and stage 2 blades, within 10 cycles after the effective 
date of this AD.
    (2) Thereafter, repeat the borescope inspection of the HPT rotor 
stage 1 and stage 2 blades within every 75 cycles-since-last-
inspection (CSLI).
    (3) Borescope-inspect the HPT rotor stage 1 and stage 2 blades 
within the cycle limits after the engine has experienced any of the 
events specified in Table 2 of this AD.
    (4) Remove any engine from service before further flight if the 
engine fails any of the borescope inspections required by this AD.

                               Table 2--Conditional Borescope Inspection Criteria
----------------------------------------------------------------------------------------------------------------
               If the engine has experienced:                              Then Borescope-Inspect:
----------------------------------------------------------------------------------------------------------------
(i) An exhaust gas temperature (EGT) above redline.........  Within 10 cycles.
(ii) A shift in the smoothed EGT trending data that exceeds  Within 10 cycles.
 18 [deg]F (10 [deg]C), but is less than or equal to 36
 [deg]F (20 [deg]C).
(iii) A shift in the smoothed EGT trending data that         Before further flight.
 exceeds 36 [deg]F (20 [deg]C).
(iv) Two consecutive raw EGT trend data points that exceed   Within 10 cycles.
 18 [deg]F (10 [deg]C) above the smoothed average, but is
 less than or equal to 36 [deg]F (20 [deg]C).
(v) Two consecutive raw EGT trend data points that exceed    Before further flight.
 36 [deg]F (20 [deg]C) above the smoothed average.
----------------------------------------------------------------------------------------------------------------

Actions Required for Engines With Damaged HPT Rotor Blades

    (g) For those engines that fail any borescope inspection 
requirements of this AD, before returning the engine to service, 
fluorescent-penetrant inspect the inner diameter surface forward 
cone body (forward spacer arm) of the LPT rotor stage 3 disk. If a 
crack is found or if a circumferential band of fluorescence appears, 
remove the disk from service.

EGT Thermocouple Probe Inspections

    (h) Inspect the EGT thermocouple probe for damage within 50 
cycles after the effective date of this AD or before accumulating 
750 CSLI, whichever occurs later.
    (i) Thereafter, re-inspect the EGT thermocouple probe for damage 
within every 750 CSLI.
    (j) If any EGT thermocouple probe shows wear through the 
thermocouple guide sleeve, remove and replace the EGT thermocouple 
probe before further flight, and ensure the turbine mid-frame liner 
does not contact the EGT thermocouple probe.

EGT System Resistance Check Inspections

    (k) Perform an EGT system resistance check within 50 cycles from 
the effective date of this AD or before accumulating 750 cycles-
since-the-last-resistance check on the EGT system, whichever occurs 
later.
    (l) Thereafter, repeat the EGT system resistance check within 
every 750 cycles-since-the-last-resistance check.
    (m) Remove and replace, or repair any EGT system component that 
fails the resistance system check before further flight.

Ultrasonic Inspection (UI) of the LPT Rotor Stage 3 Disk Forward Spacer 
Arm

    (n) Within 75 cycles after the effective date of this AD, 
perform a UI of the forward cone body (forward spacer arm) of the 
LPT rotor stage 3 disk. Use paragraphs E. through K. of Appendix A 
of GE Service Bulletin (SB) No. CF6-50-SB 72-1312, Revision 1, dated 
October 18, 2010, to do the UI.

Engine Core Vibration Survey

    (o) Within 75 cycles after the effective date of this AD, 
perform an initial engine core vibration survey.
    (1) Use approximately a one-minute acceleration and a one-minute 
deceleration of the engine between ground idle and 84% N2 (about 
8,250 rpm) to perform the engine core vibration survey.
    (2) Use a spectral/trim balance analyzer or equivalent, to 
determine the N2 rotor vibration.
    (p) Thereafter, within every 350 cycles-since-the-last-engine 
core vibration survey, perform the engine core vibration survey as 
required in paragraphs (o)(1) through (o)(2) of this AD.
    (q) If the vibration level is above 5 mils Double Amplitude then 
before further flight, remove the engine from service.
    (r) For those engines that fail any engine core vibration survey 
requirements of this AD, before returning the engine to service, 
fluorescent-penetrant inspect the inner diameter surface forward 
cone body (forward spacer arm) of the LPT rotor stage 3 disk. If a 
crack is found or if a circumferential band of fluorescence appears, 
remove the disk from service.
    (s) If the engine has experienced any vibration reported by 
maintenance or flight crew that is suspected to be caused by the HPT 
rotor (N2), perform the engine core vibration survey as required in 
paragraphs (o)(1) through (o)(2) of this AD within 10 cycles after 
the report.
    (t) You can find further guidance about performing the engine 
core vibration survey in GE SB No. CF6-50-SB 72-1313, Revision 1, 
dated October 18, 2010.

Reporting Requirements

    (u) Report to the FAA within 10 days after any of the following:
    (1) Any crack findings; and
    (2) Any disks that failed a UI performed as specified in 
paragraph (n) of this AD; and
    (3) Any engines that failed an engine core vibration survey as 
specified in paragraphs (o) and (p) of this AD.
    (4) Submit these findings to FAA, Engine & Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803; e-

[[Page 6326]]

mail: [email protected]; phone: 781-238-7735; fax: 781-238-
7199.

Paperwork Reduction Act Burden Statement

    (5) A federal agency may not conduct or sponsor, and a person is 
not required to respond to, nor shall a person be subject to a 
penalty for failure to comply with a collection of information 
subject to the requirements of the Paperwork Reduction Act unless 
that collection of information displays a current valid OMB Control 
Number. The OMB Control Number for this information collection is 
2120-0056. Public reporting for this collection of information is 
estimated to be approximately 5 minutes per response, including the 
time for reviewing instructions, completing and reviewing the 
collection of information. All responses to this collection of 
information are mandatory. Comments concerning the accuracy of this 
burden and suggestions for reducing the burden should be directed to 
the FAA at: 800 Independence Ave., SW., Washington, DC 20591, Attn: 
Information Collection Clearance Officer, AES-200.

Definitions

    (v) For the purposes of this AD, an EGT above redline is a 
confirmed over-temperature indication that is not a result of EGT 
system error.
    (w) For the purposes of this AD, a shift in the smoothed EGT 
trending data is a shift in a rolling average of EGT that can be 
confirmed by a corresponding shift in the trending of fuel flow or 
fan speed/core speed (N1/N2) relationship. You can find further 
guidance about evaluating EGT trend data in GE Company Service Rep 
Tip 373 ``Guidelines For Parameter Trend Monitoring.''

Previous Credit

    (x) A borescope inspection performed before the effective date 
of this AD using AD 2010-06-15, Amendment 39-16240 (75 FR 12661, 
March 17, 2010) or AD 2010-12-10, Amendment 39-16331 (75 FR 32649, 
June 9, 2010) within the last 75 cycles, satisfies the initial 
borescope inspection requirement in paragraph (f)(1) of this AD.
    (y) A UI performed before the effective date of this AD using GE 
SB No. CF6-50-SB 72-1312, dated August 9, 2010 or GE SB No. CF6-50-
SB 72-1312 Revision 1, dated October 18, 2010, satisfies the 
inspection requirement in paragraph (n) of this AD.
    (z) An engine core vibration survey performed before the 
effective date of this AD using GE SB No. CF6-50-SB 72-1313, dated 
August 9, 2010 or GE SB No. CF6-50-SB 72-1313 Revision 1, dated 
October 18, 2010, within the last 350 cycles, satisfies the initial 
survey requirement in paragraph (o) of this AD.

Alternative Methods of Compliance (AMOCs)

    (aa) AMOCs previously approved for AD 2010-06-15, Amendment 39-
16240 (75 FR 12661, March 17, 2010) are not approved for this AD. 
However, AMOCs previously approved for AD 2010-12-10, Amendment 39-
16331 (75 FR 32649, June 9, 2010) are approved for this AD.
    (bb) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (cc) Contact Tomasz Rakowski, Aerospace Engineer, Engine 
Certification Office, FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803; phone: 781-238-7735; 
fax: 781-238-7199; e-mail: [email protected], for more 
information about this AD.

Material Incorporated by Reference

    (dd) You must use GE Service Bulletin No. CF6-50-SB 72-1312, 
Revision 1, dated October 18, 2010, to do the ultrasonic inspections 
required by this AD.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service bulletin in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) Contact General Electric Company, GE-Aviation, Room 285, 1 
Neumann Way, Cincinnati, OH 45215, telephone (513) 552-3272; fax 
(513) 552-3329; e-mail: [email protected] for a copy of this service 
information.
    (3) You may review copies at the FAA, New England Region, 12 New 
England Executive Park, Burlington, MA. For information on the 
availability of this material at the FAA, call 781-238-7125.
    (4) You may also review copies of the service information that 
is incorporated by reference at the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on January 14, 2011.
Peter A. White,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-2387 Filed 2-3-11; 8:45 am]
BILLING CODE 4910-13-P

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