[Federal Register Volume 76, Number 238 (Monday, December 12, 2011)]
[Rules and Regulations]
[Pages 77108-77111]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-31663]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0494; Directorate Identifier 2010-NE-20-AD; 
Amendment 39-16884; AD 2011-25-08]
RIN 2120-AA64


Airworthiness Directives; International Aero Engines Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for 
International Aero Engines (IAE) V2500-A1, V2522-A5, V2524-A5, V2525-
D5, V2527-A5, V2527E-A5, V2527M-A5, V2528-D5, V2530-A5, and V2533-A5 
turbofan engines. This AD was prompted by three reports of high-
pressure turbine (HPT) case burn-through events, numerous reports of 
loss of stage 1 blade outer air seal segments, and HPT case bulging. 
This AD requires initial and repetitive 360 degree borescope 
inspections of HPT stage 1 blade outer air seal segments for evidence 
of certain distress conditions. This AD also requires incorporation of 
improved durability stage 1 blade outer air seal segments at the next 
exposure to the HPT module subassembly as terminating action to the 
repetitive inspections. We are issuing this AD to prevent HPT case 
burn-through, uncontrolled under-cowl engine fire, and damage to the 
airplane.

DATES: This AD is effective January 17, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of January 17, 
2012.

ADDRESSES: For service information identified in this AD, contact 
International Aero Engines AG, 628 Hebron Avenue, Suite 400, 
Glastonbury, CT 06033; phone: (860) 368-3700; fax: (860) 368-4600; 
email: [email protected]; Web site: https://www.iaeworld.com. You 
may review copies of the referenced service information at the FAA, 
Engine & Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803. For information on the availability of this 
material at the FAA, call (781) 238-7125.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the

[[Page 77109]]

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 address for the Docket Office (phone: (800) 647-5527) is Document 
Management Facility, U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Carlos Fernandes, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; phone: (781) 238-
7189; fax: (781) 238-7199, email: [email protected].

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an AD that would apply to the specified products. 
That NPRM published in the Federal Register on November 23, 2010 (75 FR 
71373). That NPRM proposed to require initial and repetitive 360 degree 
borescope inspections of HPT stage 1 blade outer air seal segments for 
evidence of distress. That NPRM also proposed to require incorporation 
of improved design stage 1 blade outer air seal segments at the next 
exposure to the HPT module subassembly.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
and the FAA's response to each comment.

Request To Increase Repetitive Inspection Interval

    A commenter, JetBlue Airways (JetBlue), requested that the 
repetitive borescope inspection interval be increased from 1,200 hours 
to either 1,500 or 2,000 hours. JetBlue requested the change to 
coincide with the recent extension of its JetBlue maintenance check to 
1,500 hours or its existing borescope inspection interval of 2,000 
hours per its maintenance planning document.
    We disagree. We based the 1,200 hour interval on risk analysis and 
it demonstrates a minimum level of safety. JetBlue did not offer data 
to support an increase in the repetitive inspection interval. We did 
not change the AD in response to this comment.

Request To Use Modified Parts That Have Been Reworked

    Three commenters, Lufthansa Technik AG, United Airlines, and TAM 
Airlines, requested that the FAA allow use of modified parts that have 
been reworked as a terminating action.
    We disagree. The commenters did not provide data to suggest that 
the modified parts would correct the unsafe condition. Applicants are 
allowed to propose alternative methods of compliance per paragraph (h) 
of this AD. We did not change the AD in response to this comment.

Request To Make Compliance Not Based on Exhaust Gas Temperature (EGT) 
Margin

    One commenter, Japan Airlines, asked that compliance be changed so 
it does not depend on EGT margin or so that a longer period of time is 
allowed to check EGT margin.
    We disagree. The unsafe condition identified in this AD develops 
due to blade outer air seal degradation which is related to reduced EGT 
margin. The EGT margin criteria in Table 1 of the compliance section of 
this AD were developed based on field data. Operators who lack EGT 
margin capture systems may develop an acceptable method to evaluate EGT 
margin or assume the EGT margin criteria in Table 1 have been met. We 
did not change the AD in response to this comment.

Request To Clarify EGT Margin

    Three commenters, United Airlines, Japan Airlines, and Delta 
Airlines, requested that EGT margin be clarified.
    We agree. We revised paragraph (f) of this AD by providing 
additional guidance on EGT margin.

Request To Establish Corrective Action for Each Operator's Environment

    One commenter, Japan Airlines, asked that corrective action be 
established for each operator's operational environment. The commenter 
believes this change is justified because its blade outer air seals 
(BOASs) are in good condition.
    We disagree. The EGT margin requirement in this AD accounts for the 
operating environment. The calculation of operating hours to inspect 
begins when all three criteria in Table 1 exceed requirements. We did 
not change the AD in response to this comment.

Request To Vary EGT Margin

    Two commenters, Japan Airlines and TAM Airlines, requested to vary 
EGT margin based on EGT redline/thrust level. The commenters believe 
EGT trigger margin is too high and should be reduced.
    We disagree. EGT margin will vary based on thrust level so there is 
no need to reduce or vary it. We have also seen reports that lower 
redline/thrust engines with 45 degree Celsius margins have also 
experienced BOAS damage. We did not change the AD in response to this 
comment.

Request To Address Intersecting Axial and Circumferential Cracks

    One commenter, Delta Airlines, asked that we address intersecting 
axial and circumferential cracks.
    We agree. We revised the AD by updating the SB V2500-ENG-72-0580 
from revision 2 to revision 3 in paragraph (f), ``Borescope 
Inspections.'' Revision 3 of this SB provides revised criteria for 
intersecting axial and circumferential cracks.

Request To Clarify Terminating Action Requirement

    One commenter, Delta Airlines, asked that we clarify the 
terminating action requirement. Delta Airlines indicated that it is 
unclear if the terminating action for this AD is required or is 
optional and requested further definition of the HPT module exposure. 
Delta Airlines also asked that the paragraph in the terminating action 
requirement that refers to concurrent requirements be modified to 
identify the piece part stage 1 support assembly.
    We agree. Terminating action is mandatory. To eliminate any 
uncertainty, we revised the heading of the ``Terminating Action'' 
paragraph to ``Mandatory Terminating Action'' to clarify that this 
action is required. We also added a definition of HPT module exposure 
to the Mandatory Terminating Action paragraph to improve clarity. We 
further modified this paragraph by changing the concurrent requirement 
paragraph references to identify the piece part stage 1 support 
assembly.

Request To Change Engine Inspection Criteria

    One commenter, TAM Airlines, requested that the criteria for engine 
inspection be determined by EGT margin deterioration rate instead of a 
fixed EGT margin value. TAM Airlines asked that the current engine 
inspection criteria be merged with high EGT margin deterioration rate 
([deg]C/1000FH) and or EGT margin abrupt trend shifts.
    We disagree. EGT margin allows the operator to use more of the 
available stage 1 blade outer air seal segments life and correlates 
with the air seal degradation. We did not change the AD in response to 
this comment.

[[Page 77110]]

Request To Provide Guidance on Engine Position Changes

    One commenter, TAM Airlines, asked for guidance on how to manage 
engine position changes after going back above the EGT margin 
threshold.
    We agree. We revised the Borescope Inspections paragraph to provide 
additional clarification on engine position changes.

Additional Information on Unsafe Condition

    One commenter, Airbus, supported the FAA's position on repetitive 
inspections and noted that the potential pylon lower spar damage caused 
by HPT case burn-through would not prevent continued safe flight and 
landing of the aircraft.
    We disagree. The description used in the AD adequately describes 
the unsafe condition. We did not change the AD in response to this 
comment.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (75 FR 71373, November 23, 2010) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (75 FR 71373, November 23, 2010).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of the AD.

Costs of Compliance

    We estimate that this AD affects 34 V2500 A1 series and 510 V2500 
A5/D5 series engines installed on airplanes of U.S. registry. We also 
estimate that it will take about 3 work-hours per engine to perform one 
inspection, about 3 work-hours per engine to install the improved 
durability stage 1 blade outer air seal segments, and that the average 
labor rate is $85 per work-hour. Required parts cost about $150,882 
(V2500 A1 series) and $155,195 (V2500 A5/D5 series) per engine. Based 
on these figures, we estimate the total cost of the AD to U.S. 
operators to be $84,556,878.

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 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 adding the following new airworthiness 
directive (AD):

2011-25-08 International Aero Engines: Amendment 39-16884; Docket 
No. FAA-2010-0494; Directorate Identifier 2010-NE-20-AD.

(a) Effective Date

    This AD is effective January 17, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to International Aero Engines (IAE) V2500-A1, 
V2522-A5, V2524-A5, V2525-D5, V2527-A5, V2527E-A5, V2527M-A5, V2528-
D5, V2530-A5, and V2533-A5 turbofan engines.

(d) Unsafe Condition

    This AD results from three reports received of high-pressure 
turbine (HPT) case burn-through events. There have also been 
numerous shop reports of loss of stage 1 blade outer air seal 
segments, and HPT case bulging. We are issuing this AD to prevent 
HPT case burn-through, uncontrolled under-cowl engine fire, and 
damage to the airplane.

(e) Compliance

    (1) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.
    (2) For engines that have incorporated IAE Service Bulletin (SB) 
No. V2500-ENG-72-0483, Revision 3 or earlier, or IAE SB No. V2500-
ENG-72-0542, Revision 1 or earlier, no further action is required.

(f) Borescope Inspections

    (1) Perform 360 degree borescope inspections of the HPT stage 1 
blade outer air seal segments for evidence of the distress 
conditions listed in Appendix D of IAE SB No. V2500-ENG-72-0580, 
Revision 3, dated August 23, 2011.
    (2) For V2525-D5 and V2528-D5 turbofan engines:
    (i) Inspect within 1,000 operating hours after the engine meets 
all criteria as defined in Table 1 of this AD, or within 600 
operating hours after the effective date of this AD, whichever is 
greater.
    (ii) Thereafter, re-inspect within every 1,000 operating hours 
or as defined in Appendix D of IAE SB No. V2500-ENG-72-0580, 
Revision 3, dated August 23, 2011, whichever is less.
    (iii) Use Accomplishment Instructions paragraphs 3.B.(1) through 
3.B.(3), and Appendices A through D of IAE SB No. V2500-ENG-72-0580, 
Revision 3, dated August 23, 2011, to do these inspections.
    (3) For V2500-A1, V2522-A5, V2524-A5, V2527-A5, V2527E-A5, 
V2527M-A5, V2530-A5, and V2533-A5 turbofan engines:
    (i) Inspect within 1,200 operating hours after the engine meets 
all criteria as defined in Table 1 of this AD, or within 600 
operating hours after the effective date of this AD, whichever is 
greater.
    (ii) Thereafter, re-inspect within every 1,200 operating hours 
or as defined in Appendix D of IAE SB No. V2500-ENG-72-0580, 
Revision 3, dated August 23, 2011, whichever is less.
    (iii) Use Accomplishment Instructions paragraphs 3.A.(1) through 
3.A.(3), and Appendices A through D of IAE SB No.

[[Page 77111]]

V2500-ENG-72-0580, Revision 3, dated August 23, 2011, to do these 
inspections.

                  Table 1--Stage 1 Blade Outer Air Seal Segment Inspection Compliance Criteria
----------------------------------------------------------------------------------------------------------------
                                       Stage 1 blade outer air  Stage 1 blade outer air        Exhaust gas
                                         seal segments hours-    seal segments cycles-      temperature margin
             Engine model              since-new or since-last- since-new or since-last- degrees  Celsius  (less
                                        repair  (greater than)   repair  (greater than)           than)
----------------------------------------------------------------------------------------------------------------
A1...................................                    6,000                    3,800                       45
A5...................................                    6,000                    3,500                       45
D5...................................                    5,000                    3,500                       45
----------------------------------------------------------------------------------------------------------------

     (4) Exhaust Gas Temperature Margin is defined as the expected 
margin during a sea-level takeoff on a 30-degree Celsius Outside Air 
Temperature Day. Guidance on how to calculate EGT margin can be 
found in IAE SIL 057. EGT margin smoothed data (data averaged over 6 
consecutive flights) is to be compared with the criteria in Table 1. 
If a gap in EGT data exists due to temporary loss of data, you may 
use linear interpolation. Calculate operating hours from the point 
when all criteria exceed the requirements in Table 1.
    (5) Except as provided below, the inspection of paragraphs 
(f)(2)(i) through (f)(2)(iii) and (f)(3)(i) through (f)(3)(iii) must 
be performed after all the criteria in Table 1 are satisfied; 
regardless of subsequent EGT margin calculations or engine rating 
changes. Temporary EGT margin excursions below the criteria in Table 
1 that are corrected with simple troubleshooting methods (e.g., LRU 
(line replaceable unit) replacement or correction of a measurement 
error) do not constitute satisfying the criteria in Table 1.

(g) Mandatory Terminating Action

    (1) As terminating action to the repetitive 360 degree borescope 
inspections required in paragraphs (f)(2)(ii) and (f)(3)(ii) above, 
install improved durability stage 1 blade outer air seal segments at 
the next HPT module subassembly exposure, which is defined as 
separation of the HPT module mating flanges.
    (i) For V2500-A1 turbofan engines, use paragraphs 1.B., 
Concurrent Requirements, and paragraphs 3.(1)(a), 3.(1)(b)(iii), and 
3.(2)(a) of the Accomplishment Instructions of IAE SB No. V2500-ENG-
72-0542, Revision 1, dated January 7, 2009, to do the installation.
    (ii) For V2522-A5, V2524-A5, V2525-D5, V2527-A5, V2527E-A5, 
V2527M-A5, V2528-D5, V2530-A5, and V2533-A5 turbofan engines, use 
paragraphs 1.B., Concurrent Requirements, and paragraphs 3.(1)(a), 
3.(1)(b), 3.(1)(c)(ii), and 3.(2)(a) of the Accomplishment 
Instructions of IAE SB No. V2500-ENG-72-0483, Revision 3, dated 
January 7, 2009, to do the installation.
    (iii) Both IAE SBs No. V2500-ENG-72-0542, Revision 1, and SB No. 
V2500-ENG-72-0483, Revision 3, require modification of the stage 1 
HPT support assembly before installing the new blade outer air seal 
segments. You must complete the modification using those SBs, as 
applicable to the appropriate engine model, to properly perform the 
mandatory terminating action of this AD.

(h) Alternative Methods of Compliance

    The Manager, Engine Certification Office, may approve 
alternative methods of compliance for this AD. Use the procedures 
found in 14 CFR 39.19 to make your request.

(i) Related Information

    (1) For more information about this AD, contact Carlos 
Fernandes, Aerospace Engineer, Engine Certification Office, FAA, 
Engine & Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803; phone: (781) 238-7189; fax: (781) 238-7199; 
email: [email protected].
    (2) Contact International Aero Engines AG, 628 Hebron Avenue 
Suite 400, Glastonbury, CT 06033; phone: (860) 368-3700; fax: (860) 
368-4600; email: [email protected]; Web site: https://www.iaeworld.com; for a copy of the service information referenced 
in this AD.

(j) Material Incorporated by Reference

    (1) You must use the following service information to do the 
actions required by this AD, unless the AD specifies otherwise. The 
Director of the Federal Register approved the incorporation by 
reference (IBR) under 5 U.S.C. 552(a) and 1 CFR part 51 of the 
following service information on the date specified:
    (i) International Aero Engines (IAE) SB No. V2500-ENG-72-0580, 
Revision 3, dated August 23, 2011, approved for IBR January 17, 
2012.
    (ii) IAE SB No. V2500-ENG-72-0542, Revision 1, dated January 7, 
2009, approved for IBR January 17, 2012.
    (iii) IAE SB No. V2500-ENG-72-0483, Revision 3, dated January 7, 
2009, approved for IBR January 17, 2012.
    (2) For service information identified in this AD, contact 
International Aero Engines AG, 628 Hebron Avenue, Suite 400, 
Glastonbury, CT 06033; phone: (860) 368-3700; fax: (860) 368-4600; 
email: [email protected]; Web site: https://www.iaeworld.com.
    (3) You may review copies of the service information at the FAA, 
Engine & Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803. 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 an NARA facility, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Burlington, MA, on November 30, 2011.
Peter A. White,
Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-31663 Filed 12-9-11; 8:45 am]
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