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[Federal Register Volume 77, Number 66 (Thursday, April 5, 2012)]
[Rules and Regulations]
[Pages 20511-20515]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-8038]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0858; Directorate Identifier 2010-NM-183-AD; 
Amendment 39-16974; AD 2012-05-02]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
The Boeing Company Model 737-600, -700, -700C, -800, and -900 series 
airplanes. This AD was prompted by reports of heat damage to the inner 
wall of the thrust reversers, which could result in separation of 
adjacent components and consequent structural damage to the airplane, 
damage to other airplanes, and injury to people on the ground. This AD 
requires modifying the thrust reverser inner walls, inspecting for 
damage of the upper and lower inner wall insulation blankets, measuring 
the electrical conductivity on the aluminum upper compression pads 2 
and 3 as applicable, inspecting for discrepancies of the inner wall of 
the thrust reverser, and corrective actions if necessary. This AD also 
requires, for certain airplanes, doing various concurrent actions 
(including replacing the inner wall blanket insulation, installing 
updated full-authority digital electronic control software, and 
modifying the thrust reverser inner wall and insulation blankets). We 
are issuing this AD to correct the unsafe condition on these products.

DATES: This AD is effective May 10, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of May 10, 2012.

ADDRESSES: For Boeing service information identified in this AD, 
contact Boeing Commercial Airplanes, Attention: Data & Services 
Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; 
telephone 206-544-5000, extension 1; fax 206-766-5680; email 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com. For CFM 
service information identified in this AD, contact CFM International, 
Technical Publications Department, 1 Neumann Way, Cincinnati, Ohio 
45215; phone: 513-552-2800; fax: 513-552-2816; Internet: http://www.cfm56.com. You may review copies of the referenced service 
information at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue SW., Renton, Washington. For information on the availability of 
this material at the FAA, call 425-227-1221.

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 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: Chris Parker, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 425-
917-6496; fax: 425-917-6590; email: chris.r.parker@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER 
series airplanes. That NPRM was published in the Federal Register on 
September 27, 2010 (75 FR 59167). That NPRM proposed to require 
modifying the inner walls of the thrust reverser (TR), inspecting for 
damage of the upper and lower inner wall insulation blankets, measuring 
the electrical conductivity on the aluminum upper compression pads 2 
and 3 as applicable, inspecting for discrepancies of the TR inner wall, 
and corrective actions if necessary. That NPRM also proposed to 
require, for certain airplanes, doing various concurrent actions 
(including replacing the inner wall blanket insulation, installing 
updated full-authority digital electronic control software, and 
modifying the TR inner wall and insulation blankets).

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
(75 FR 59167, September 27, 2010) and the FAA's response to each 
comment.

Request To Withdraw NPRM (75 FR 59167, September 27, 2010)

    Despite fully supporting the implementation of the actions of the 
NPRM (75 FR 59167, September 27, 2010), Boeing stated that it does not 
consider thermal overheat on the TR inner walls on the affected 
airplanes to be a safety issue. The structural integrity of the inner 
wall may deteriorate due to pre-cooler air ingress behind the blankets, 
but the Boeing Safety Review Board determined that this does not 
constitute a safety hazard to the airplane or to persons on the ground. 
Boeing identified support data for this determination, which included a 
safety assessment, full-scale test demonstration, and structural 
analysis.
    We infer that Boeing wants us to withdraw the NPRM (75 FR 59167, 
September 27, 2010), because there is no unsafe condition. We disagree. 
The thermal overheat could affect the structural capability of the 
inner wall of the thrust reverser such that, if a pneumatic duct 
bursts, the inner wall could fail, causing uncontrollable asymmetric 
thrust during a rejected takeoff, or causing large parts to hit the 
fuselage or empennage in flight.

[[Page 20512]]

Request To Remove Model 737-900ER

    Boeing requested that we remove Model 737-900ER series airplanes 
from the applicability of the NPRM (75 FR 59167, September 27, 2010), 
since configuration control prevents the intermix of the affected TRs 
on these airplanes.
    We agree. The TR inner walls on Model 737-900ER series airplanes 
have not been identified as having a thermal overheat issue. We have 
therefore removed these airplanes from the applicability of this AD.

Comments on EASA Proposed AD (75 FR 59167, September 27, 2010)

    The European Aviation Safety Agency (EASA), which is the Technical 
Agent for the Member States of the European Community, issued Proposed 
AD 10-087, dated September 30, 2010 (which has since been issued as 
EASA AD 2010-0244R1, dated May 17, 2011, and corresponds to FAA NPRM 
(75 FR 59167, September 27, 2010)). Boeing reported that it had 
requested certain changes (to the compliance time and applicability) to 
the EASA Proposed AD, and provided a list of the specific requests 
including changing the compliance time and eliminating language 
regarding certain ``specific airplane(s).''
    We find these comments to be addressed to EASA Proposed AD 10-087 
and do not apply to the FAA proposed AD (75 FR 59167, September 27, 
2010). The applicability is the same in the EASA and FAA ADs, and 
accounts for Boeing's comment concerning Model 737-900ER series 
airplanes. The compliance time of the EASA AD is different from that of 
the FAA AD, based on differing AD processes and publication schedules. 
We have not changed the final rule regarding this issue.

Request To Revise Cost Estimate

    Continental Airlines (CAL) disagreed with the fleet cost estimates 
for the actions specified in Boeing Service Bulletin 737-78-1088, dated 
May 12, 2010, as proposed in paragraph (i) of the NPRM (75 FR 59167, 
September 27, 2010). CAL explained that inner wall delamination 
requires the repair to be performed in an autoclave, which requires 
disassembly of the TR. (There are two half TR sections per engine.) CAL 
stated that returning each TR half to service after disassembly and 
inspection of components could cost from $16,000 to $56,000, depending 
on the hours and cycles on the TR.
    We disagree with the request to revise the cost estimate. The 
economic analysis of the NPRM (75 FR 59167, September 27, 2010) did not 
consider the cost of conditional actions, such as repairing damage 
detected during a required inspection. The economic analysis of this AD 
is limited to the cost of actions that are required of every operator. 
Such conditional repairs would be required--regardless of AD 
direction--to correct an unsafe condition identified in an airplane and 
to ensure that the airplane is operated in an airworthy condition, as 
required by the Federal Aviation Regulations. We would have no way of 
determining these on-condition costs, which would depend on the TR 
condition and vary from operator to operator. We have not changed the 
final rule regarding this issue.

Request To Extend Compliance Time for Modification

    Three commenters requested that we revise the 24-month compliance 
time for the modification specified in paragraph (g) of the NPRM (75 FR 
59167, September 27, 2010).
    CAL requested that we extend the compliance time to 30 months, when 
116 of its airplanes will also require the inspection specified in 
paragraph (i) of the proposed AD (75 FR 59167, September 27, 2010). 
This compliance time extension would reduce CAL's modifications on its 
fleet from 5 airplanes to 4 airplanes per month. CAL added that, even 
with this extended compliance time, it would be difficult to modify 4 
(16 TR halves) per month because of the limited number of spare TR 
halves available.
    Southwest Airlines (SWA) reported that it would need to modify 39 
of its 946 TRs each month to meet a 24-month compliance time, and 
therefore suggested a stepped compliance time schedule, ranging from 12 
months to 48 months, based on the service life of the TR.
    American Airlines (AAL) stated that the 24-month compliance time 
will have a significant impact on its ``light'' C check.
    We disagree to extend the compliance time for paragraph (g) of this 
AD. In developing an appropriate compliance time for these actions, we 
considered the urgency associated with the subject unsafe condition, 
the practical aspect of accomplishing the required modification and the 
normal scheduled maintenance times for most affected operators. In 
consideration of these items and of parts availability, we have 
determined that the proposed 24-month compliance time for the 
modification will ensure an acceptable level of safety. According to 
the provisions of paragraph (o) of this AD, however, we may approve 
requests to adjust the compliance time if the request includes data 
substantiating that the new compliance time would provide an acceptable 
level of safety. We have not changed the final rule regarding this 
issue.

Request To Clarify Service Information

    AAL requested that the service instructions for Boeing Service 
Bulletin 737-78-1082, dated March 25, 2010; and Boeing Service Bulletin 
737-78-1088, dated May 12, 2010; be revised to incorporate general 
findings and clarifications. AAL asserted that not addressing these 
issues could adversely affect accomplishment of these service 
bulletins.
    We agree that additional clarification would be beneficial in the 
identified areas of Boeing Service Bulletin 737-78-1082, dated March 
25, 2010; and Boeing Service Bulletin 737-78-1088, dated May 12, 2010. 
Such minor clarifications, however, are not necessary for compliance 
with this AD. We have provided AAL's comments to Boeing for review and 
incorporation, as necessary, into future revisions of those service 
bulletins, which might be approved as a global alternative method of 
compliance with this AD if we can substantiate that the revision 
provides an acceptable level of safety. We have not changed the final 
rule regarding this issue.

Request for Optional Repair

    SWA requested that we revise paragraph (i) of the NPRM (75 FR 
59167, September 27, 2010) to allow cold-bonding methods for repairing 
damaged areas, in addition to the autoclave procedures specified in 
Boeing Service Bulletin 737-78-1088, dated May 12, 2010. That service 
bulletin permits curing repaired areas only as specified in the Boeing 
737-700 Structural Repair Manual (SRM), which specifies the autoclave 
procedures. According to SWA, this would require operators to pull TRs 
for repair at an approved overhaul facility, thereby increasing the 
turn time for repairs since only five Boeing-approved overhaul 
facilities have autoclave capabilities.
    We disagree with the request to allow the cold-bonding procedure. 
Boeing and the FAA are unaware of any cold-bonding methods that would 
be applicable to the composite TR inner wall on the affected airplanes. 
Current SRM repair methods for composite structure involve either 
autoclave or vacuum bag/heat blanket cure methods. But Boeing Service 
Bulletin 737-78-1088, dated May 12, 2010, and the

[[Page 20513]]

alternative Boeing Service Bulletin 737-78-1079, Revision 2, dated June 
7, 2010, limit the SRM repairs for the TR inner wall to autoclave 
cures. For the areas being repaired on the inner wall, the additional 
plies required to make a structurally adequate vacuum bag-cured repair 
are excessive and would make the inner wall unusable. We therefore find 
it appropriate for those service bulletins to specify autoclave curing 
only. In addition, Boeing has evaluated the potential number of repairs 
that would be done at overhaul facilities with autoclave capabilities, 
and does not foresee a problem addressing the corrective actions on the 
affected airplanes within the compliance times. We have not changed the 
final rule regarding this issue.

Request To Revise Compliance Time for Certain Inspections

    SWA requested that we revise paragraph (i) of the proposed AD (75 
FR 59167, September 27, 2010), which proposed certain inspections in 
accordance with Boeing Service Bulletin 737-78-1088, dated May 12, 
2010. SWA recommended a minimum of 48 months, ``per [this service 
bulletin],'' for these actions. (The compliance time in the proposed AD 
ranged from 30 to 96 months.)
    We disagree with the request. As stated previously, when we 
developed the compliance time for this AD action we considered the 
safety implications of the identified unsafe condition, the average 
utilization rate of the affected fleet, the practical aspects of 
performing the inspections on the fleet during regular maintenance 
periods, and the availability of replacement parts. We have determined 
that the proposed compliance times are appropriate. We have not changed 
the final rule regarding this issue.

Request for Clarification of Certain Procedures

    AAL described difficulty in accomplishing the actions specified in 
Boeing Service Bulletin 737-78-1079, Revision 2, dated June 7, 2010 
(paragraph (n) of the NPRM (75 FR 59167, September 27, 2010)): Seals 
must be installed individually, the fire seal can tear and need 
replacement, and the roller edge of the insulation blanket interferes 
with the upper fire seal support flange insulations. AAL received some 
additional installation instructions from Boeing and recommended that 
they be included in this service bulletin.
    We agree that additional clarification may be beneficial, but we 
find that accomplishing the actions specified in the Accomplishment 
Instructions of Boeing Service Bulletin 737-78-1079, Revision 2, dated 
June 7, 2010, will address the identified unsafe condition. We have 
provided AAL's comments to Boeing for review and incorporation, as 
necessary, into a future service bulletin revision, which might be 
approved as an alternative method of compliance with this AD if we can 
substantiate that the revision provides an acceptable level of safety. 
We have not changed the final rule regarding this issue.

Additional Changes to NPRM (75 FR 59167, September 27, 2010)

    Paragraph (n) of this AD specifies the optional accomplishment of 
certain actions in accordance with Boeing Service Bulletin 737-78-1079, 
Revision 2, dated June 7, 2010. That service bulletin incorrectly notes 
that removal of a compression pad assembly is not necessary if the 
adjacent inner wall area does not show signs of heat damage, because 
the compression pad assembly is made from titanium. This AD requires 
removing the affected compression pads and inspecting the underlying 
structures as part of this optional action, regardless whether a pad 
assembly is made of titanium or aluminum alloy. Boeing has indicated 
that the incorrect notes may be removed in a future revision of that 
service bulletin; if so, we may approve the revised service bulletin as 
a global AMOC with the requirements of this AD.
    We have revised or added certain headers in this AD. We have also 
revised the wording in paragraphs (l) and (n) of this AD; this change 
has not changed the intent of those paragraphs.

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 change described previously. We also determined that 
this change 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 710 airplanes of U.S. registry. 
The following table provides the estimated costs for U.S. operators to 
comply with this AD, at an average labor rate of $85 per hour.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Number of  U.S.-
     Actions (service bulletin)            Work hours                 Parts             Cost per product    registered  airplanes        Fleet cost
--------------------------------------------------------------------------------------------------------------------------------------------------------
Modification (Boeing Service         14 per engine.........  $2,065 or $3,702......  $4,445 or $6,082.....  710..................  Up to $4,318,220.
 Bulletin 737-78-1082, dated March
 25, 2010).
Insulation replacement (Boeing       18 per engine.........  $0....................  $3,060...............  15...................  $45,900.
 Service Bulletin 737-78-1063,
 Revision 2, dated October 7, 1994).
Software update (CFM CFM56-7B        1.....................  $0....................  $85..................  Up to 710............  Up to $60,350.
 Service Bulletin 73-0135, dated
 March 30, 2007).
Inspections (Boeing Service          35....................  $0....................  $2,975...............  710..................  $2,112,250.
 Bulletin 737-78-1088, dated May
 12, 2010).
Modifications (Boeing Service        110...................  $0....................  $9,350...............  306..................  $2,861,100.
 Bulletin 737-78-1069, Revision 4,
 dated June 16, 2005).
Inspections and modification         37 per engine.........  $2,070 or $3,391......  $8,360 or $9,681.....  Optional action......  Optional action.
 (Boeing Service Bulletin 737-78-
 1079, Revision 2, dated June 7,
 2010) (if done as an option to
 Boeing Service Bulletin 737-78-
 1088 and Boeing Service Bulletin
 737-78-1082).
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 20514]]

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):

2012-05-02 The Boeing Company: Amendment 39-16974; Docket No. FAA-
2010-0858; Directorate Identifier 2010-NM-183-AD.

(a) Effective Date

    This AD is effective May 10, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, and -900 series airplanes; certificated in any category; 
as identified in Boeing Service Bulletin 737-78-1082, dated March 
25, 2010.

(d) Subject

    Air Transport Association (ATA) of America Code 78: Engine 
exhaust.

(e) Unsafe Condition

    This AD results from reports of heat damage to the inner wall of 
the thrust reversers. The Federal Aviation Administration is issuing 
this AD to detect and correct such heat damage, which could result 
in separation of adjacent components and consequent structural 
damage to the airplane, damage to other airplanes, and injury to 
people on the ground.

(f) Compliance

    You are responsible for having the actions required by this AD 
performed within the compliance times specified, unless the actions 
have already been done.

(g) Modification of Thrust Reverser Inner Wall

    Except as required by paragraph (m) of this AD: Within 24 months 
after the effective date of this AD, modify the thrust reverser 
inner wall, in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 737-78-1082, dated March 25, 2010.

(h) Actions Concurrent With Paragraph (g) of This AD

    Before or concurrently with accomplishment of the requirements 
of paragraph (g) of this AD, do the actions specified in paragraphs 
(h)(1) and (h)(2) of this AD, as applicable.
    (1) For airplanes identified in Boeing Service Bulletin 737-78-
1063, Revision 2, dated October 7, 1999: Replace the inner wall 
blanket insulation, in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 737-78-1063, Revision 2, 
dated October 7, 1999.
    (2) For airplanes equipped with engines identified in CFM CFM56-
7B Service Bulletin 73-0135, dated March 30, 2007: Install updated 
full-authority digital electronic control (FADEC) software, in 
accordance with the Accomplishment Instructions of CFM CFM56-7B 
Service Bulletin 73-0135, dated March 30, 2007.

(i) Inspection/Measurement

    At the applicable time specified in paragraph (j) of this AD: Do 
the actions specified in paragraphs (i)(1), (i)(2), and (i)(3) of 
this AD, in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 737-78-1088, dated May 12, 2010. If any 
damage or discrepancy is found, before further flight, do all 
applicable corrective actions, in accordance with Accomplishment 
Instructions of Boeing Service Bulletin 737-78-1088, dated May 12, 
2010; except as required by paragraph (k) of this AD; and except 
where the service bulletin refers to ``unsatisfactory'' findings, 
this AD assumes those parts or locations are ``unserviceable.''
    (1) Do a detailed inspection for damage of the engine side and 
inner wall side of the upper and lower insulation blankets.
    (2) Measure the electrical conductivity on the aluminum upper 
compression pads 2 and 3, as applicable.
    (3) Inspect for discrepancies of the thrust reverser inner wall 
(including an ultrasonic inspection for interply delamination and 
skin-to-core disbond, a detailed inspection for signs of heat damage 
as applicable, and a detailed inspection for loose fasteners where 
the inner wall attaches to the hinge beam and at the fasteners for 
the compression pads).

(j) Compliance Times for Paragraph (i) of This AD

    Do the actions specified in paragraph (i) of this AD at the 
applicable time specified in paragraph (j)(1), (j)(2), (j)(3), 
(j)(4), or (j)(5) of this AD.
    (1) For airplanes with thrust reverser part number (P/N) 
315A2295-003 through 315A2295-154 inclusive: Do the actions within 
30 months after the effective date of this AD.
    (2) For airplanes with thrust reverser P/N 315A2295-155 through 
315A2295-174 inclusive: Do the actions within 60 months after the 
effective date of this AD.
    (3) For airplanes with thrust reverser P/N 315A2295-175 through 
315A2295-190 inclusive: Do the actions within 72 months after the 
effective date of this AD.
    (4) For airplanes with thrust reverser P/N 315A2295-191 through 
315A2295-198 inclusive: Do the actions within 84 months after the 
effective date of this AD.
    (5) For airplanes with thrust reverser P/N 315A2295-199 through 
315A2295-202 inclusive: Do the actions within 96 months after the 
effective date of this AD.

(k) Exception to Boeing Service Bulletin 737-78-1088 Procedures

    Where Boeing Service Bulletin 737-78-1088, dated May 12, 2010, 
specifies to contact Boeing for appropriate action, repair before 
further flight in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.

[[Page 20515]]

(l) Concurrent Actions for Paragraph (i) of This AD

    For airplanes identified in Boeing Service Bulletin 737-78-1069, 
Revision 4, dated June 16, 2005: Before or concurrently with the 
accomplishment of the requirements of paragraph (i) of this AD, 
modify the thrust reverser inner wall and insulation blankets, in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 737-78-1069, Revision 4, dated June 16, 2005. This 
paragraph provides credit for the actions specified in Boeing 
Service Bulletin 737-78-1069, Revision 4, dated June 16, 2005, if 
those actions were performed before the effective date of this AD 
using Boeing Service Bulletin 737-78-1069, Revision 1, dated June 
13, 2002; Revision 2, dated February 6, 2003; or Revision 3, dated 
August 5, 2004.

(m) Concurrent Actions for Paragraph (i) of This AD Done Before the 
Compliance Time for paragraph (g) of This AD

    If the actions required by paragraph (i) of this AD are done 
before the compliance time specified in paragraph (g) of this AD: 
Before or concurrently with the accomplishment of the actions 
required by paragraph (i) of this AD, the modification required by 
paragraph (g) of this AD must be done.

(n) Option to Requirements of Paragraphs (g) and (i) of This AD

    Accomplishment of all of the actions (including inspections and 
modification) specified in Boeing Service Bulletin 737-78-1079, 
Revision 2, dated June 7, 2010, within 24 months after the effective 
date of this AD, is acceptable for compliance with the requirements 
of paragraphs (g) and (i) of this AD; except that this AD requires 
removing the affected compression pads and inspecting the underlying 
structures regardless whether a pad assembly is made of titanium or 
aluminum alloy. Accomplishment of all of the actions (including 
inspections and modification) specified in Boeing Service Bulletin 
737-78-1079, Revision 2, dated June 7, 2010, within 24 months after 
the effective date of this AD, is acceptable for compliance with the 
requirements of this AD provided applicable repairs are done before 
further flight, and provided the applicable actions specified in 
paragraphs (h)(1), (h)(2), and (l) of this AD have been done. This 
paragraph provides credit for the actions specified in Boeing 
Service Bulletin 737-78-1079, Revision 2, dated June 7, 2010, if 
those actions were done before the effective date of this AD using 
Boeing Service Bulletin 737-78-1079, dated August 6, 2007; or 
Revision 1, dated December 17, 2007.

(o) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the ACO, send it to the 
attention of the person identified in the Related Information 
section of this AD. Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(p) Related Information

    For more information about this AD, contact Chris R. Parker, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle 
Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; phone: 425-917-6496; fax: 425-917-6590; 
email: chris.r.parker@faa.gov.

(q) 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) of the following service information under 5 U.S.C. 
552(a) and 1 CFR part 51:
    (i) Boeing Service Bulletin 737-78-1063, Revision 2, dated 
October 7, 1999.
    (ii) Boeing Service Bulletin 737-78-1069, Revision 4, dated June 
16, 2005.
    (iii) Boeing Service Bulletin 737-78-1082, dated March 25, 2010.
    (iv) Boeing Service Bulletin 737-78-1088, dated May 12, 2010.
    (v) CFM CFM56-7B Service Bulletin 73-0135, dated March 30, 2007.
    (2) If you accomplish the optional actions specified by this AD, 
you must use the following service information to perform those 
actions, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference (IBR) of 
the following service information:
    (i) Boeing Service Bulletin 737-78-1079, Revision 2, dated June 
7, 2010.
    (3) For Boeing service information identified in this AD, 
contact Boeing Commercial Airplanes, Attention: Data & Services 
Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; 
telephone 206-544-5000, extension 1; fax 206-766-5680; email 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com. For 
CFM service information identified in this AD, contact CFM 
International, Technical Publications Department, 1 Neumann Way, 
Cincinnati, Ohio 45215; phone: 513-552-2800; fax: 513-552-2816; 
Internet: http://www.cfm56.com.
    (4) You may review copies of the service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, 
Washington. For information on the availability of this material at 
the FAA, call 425-227-1221.
    (5) 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 Renton, Washington, on February 22, 2012.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-8038 Filed 4-4-12; 8:45 am]
BILLING CODE 4910-13-P
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