
[Federal Register Volume 77, Number 162 (Tuesday, August 21, 2012)]
[Proposed Rules]
[Pages 50407-50411]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-20470]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0855; Directorate Identifier 2011-NM-136-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to supersede an existing airworthiness directive 
(AD) that applies to all The Boeing Company Model 737-100, -200, -200C, 
-300, -400, and -500 series airplanes. The existing AD currently 
requires repetitive inspections to detect cracking of the lower corners 
of the door frame and cross beam of the forward cargo door, and 
corrective actions if necessary. The existing AD also requires eventual 
modification of the outboard radius of the lower corners of the door 
frame and reinforcement of the cross beam of the forward cargo door, 
which would constitute terminating action for the existing repetitive 
inspections. Since we issued that AD, we have received additional 
reports of fatigue cracking in the radius of the lower frames and in 
the lower number 5 cross beam of the forward cargo door. This proposed 
AD would revise the compliance times for the preventive modification; 
add certain inspections for cracks in the number 5 cross beam of the 
forward cargo door; and add inspections of the number 4 cross beam if 
cracks are found in the number 5 cross beam, and corrective actions if 
necessary. For certain airplanes, this proposed AD would also add a 
one-time inspection for airplanes previously modified or repaired, and 
a one-time inspection of the reinforcement angle for excessive shimming 
or fastener pull-up, and corrective actions if necessary. We are 
proposing this AD to prevent fatigue cracking of the lower corners of 
the door frame and number 5 cross beam of the forward cargo door, which 
could result in rapid depressurization of the airplane.

DATES: We must receive comments on this proposed AD by October 5, 2012.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     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.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For 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; Internet https://www.myboeingfleet.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.

[[Page 50408]]

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 proposed 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: Alan Pohl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: (425) 917-
6450; fax: (425) 917-6590; email: alan.pohl@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2012-0855; 
Directorate Identifier 2011-NM-136-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed 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 proposed AD.

Discussion

    On March 31, 2000, we issued AD 2000-07-06, Amendment 39-11660 (65 
FR 19302, April 11, 2000), for Model 737-100, -200, -200C, -300, -400, 
and -500 series airplanes. That AD requires repetitive inspections to 
detect cracking of the lower corners of the door frame and cross beam 
of the forward cargo door, and corrective actions, if necessary. That 
AD also requires eventual modification of the outboard radius of the 
lower corners of the door frame and reinforcement of the cross beam of 
the forward cargo door, which would constitute terminating action for 
the repetitive inspections. That AD resulted from reports indicating 
that fatigue cracks were detected in the lower corners of the door 
frame and cross beam of the forward cargo door. We issued that AD to 
prevent fatigue cracking of the lower corners of the door frame and 
cross beam of the forward cargo door, which could result in rapid 
depressurization of the airplane.

Actions Since AD 2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 
2000) Was Issued

    Since we issued AD 2000-07-06, Amendment 39-11660 (65 FR 19302, 
April 11, 2000), we have received additional reports of fatigue 
cracking in the radius of the lower frames and in the Web of the number 
5 lower cross beam of the forward cargo door. One report was of a rapid 
loss of cabin pressure during descent, as a result of a door crack. 
Other reports indicated improper nesting when installing the aft 
reinforcement angle during accomplishment of the modification specified 
in Boeing Service Bulletin 737-52-1100, Revision 2, dated March 31, 
1994; and Boeing Alert Service Bulletin 737-52A1100, Revision 3, dated 
July 20, 2000.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-52A1100, Revision 5, 
dated February 14, 2011; and Boeing Special Attention Service Bulletin 
737-52-1149, dated December 11, 2003. For information on the procedures 
and compliance times, see this service information at http://www.regulations.gov.

FAA's Determination

    We are proposing 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 these same type 
designs.

Proposed AD Requirements

    This proposed AD would retain all of the requirements of AD 2000-
07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000). This proposed 
AD would also require accomplishing the actions specified in the 
service information described previously, except as discussed under 
``Differences Between the Proposed AD and the Service Information.'' 
Related investigative actions include inspecting the number 4 cross 
beam on the forward cargo door for cracking if cracking is found on the 
number 5 cross beam, a one-time high frequency eddy current inspection 
for cracking of the lower corner frame, and a one-time inspection of 
the reinforcement angle. Corrective actions include the following: 
Installing a preventive modification, replacing the frame and repairing 
any cracking, repairing or replacing the number 5 cross beam, and 
replacing the reinforcement angle.

Explanation of Changes Made to Existing Requirements

    The compliance times required by AD 2000-07-06, Amendment 39-11660 
(65 FR 19302, April 11, 2000), are specified in flight cycles on the 
airplane. However, the compliance times in the new actions specified in 
the revised service information are specified in door flight cycles, 
which are flight cycles accumulated on the forward cargo doors. These 
doors are interchangeable between airplanes and they are often 
interchanged. Since the unsafe condition stems from the total flight 
cycles accumulated on the door and not on the airplane itself, this 
proposed AD will specify door flight cycles for the new compliance 
times.
    We have changed all references to a ``detailed visual inspection'' 
in the retained requirements of the existing AD to a ``detailed 
inspection'' in this proposed AD.
    Boeing Commercial Airplanes has received an ODA. We have revised 
the retained requirements of the existing AD to delegate the authority 
to approve an alternative method of compliance for any repair required 
by this proposed AD to the Boeing Commercial Airplanes ODA rather than 
a Designated Engineering Representative (DER).
    We have included Note 2 of the restated requirements of AD 2000-07-
06, Amendment 39-11660 (65 FR 19302, April 11, 2000), in paragraph (h) 
of this proposed AD. Note 3 of the restated requirements of AD 2000-07-
06 is no longer applicable and has been removed from this proposed AD. 
These changes do not add any additional burden on the public with 
regard to the restated requirements of the existing AD.
    We have added Boeing Alert Service Bulletin 737-52A1100, Revision 
5, dated February 14, 2011, to paragraph (i)(2) of this AD as the 
source of service information for accomplishing the preventive 
modification and the reinforcement modification.

Differences Between the Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-52A1100, Revision 5, dated 
February 14, 2011, specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:

[[Page 50409]]

     In accordance with a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by the Boeing Commercial 
Airplanes Organization Designation Authorization (ODA) whom we have 
authorized to make those findings.

Changes to Existing AD 2000-07-06, Amendment 39-11660 (65 FR 19302, 
April 11, 2000) Format

    This proposed AD would retain all requirements of AD 2000-07-06, 
Amendment 39-11660 (65 FR 19302, April 11, 2000). Since AD 2000-07-06 
was issued, the AD format has been revised, and certain paragraphs have 
been rearranged. As a result, the corresponding paragraph identifiers 
have changed in this proposed AD, as listed in the following table:

                      Revised Paragraph Identifiers
------------------------------------------------------------------------
Requirement in AD 2000-07-06, Amendment
 39[dash]11660 (65 FR 19302, April 11,     Corresponding requirement in
                 2000)                           this proposed AD
------------------------------------------------------------------------
paragraph (a)                            paragraph (g)
paragraph (b)                            paragraph (h)
paragraph (c)                            paragraph (i)
paragraph (d)                            paragraph (j)
------------------------------------------------------------------------

Explanation of Change to Costs of Compliance

    Since issuance of AD 2000-07-06, Amendment 39-11660 (65 FR 19302, 
April 11, 2000), we have increased the labor rate used in the Costs of 
Compliance from $80 per work-hour to $85 per work-hour. The Costs of 
Compliance information, below, reflects this increase in the specified 
labor rate.

Costs of Compliance

    We estimate that this proposed AD affects 581 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Action                        Labor cost          Parts cost      Cost per product                   Cost on U.S. operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspections retained from AD 2000-07-  1 work-hour x $85 per              $0  $85 per inspection cycle  $49,385 per inspection cycle.
 06, Amendment 39[dash]11660 (65 FR     hour = $85 per
 19302, April 11, 2000).                inspection cycle.
Modification retained from AD 2000-07- 18 work-hours x $85 per        $1,865  $3,395..................  $1,972,495.
 06.                                    hour = $1,530.
Inspections, new proposed action.....  9 work-hours x $85 per             $0  $765....................  $444,465.
                                        hour = $765.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We estimate the following costs to do any necessary modifications 
that would be required based on the results of the proposed 
inspections. We have no way of determining the number of aircraft that 
might need these modifications:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                  Action                                Labor cost                 Parts cost        product
----------------------------------------------------------------------------------------------------------------
Modification..............................  84 work-hours x $85 per hour =             $12,395          $19,535
                                             $7,140.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for the on-condition repairs/replacements specified in 
this proposed AD.

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

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under the 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.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by removing airworthiness directive 
(AD)

[[Page 50410]]

2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2012-0855; Directorate Identifier 
2011-NM-136-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by October 5, 
2012.

(b) Affected ADs

    This AD supersedes AD 2000-07-06, Amendment 39-11660 (65 FR 
19302, April 11, 2000).

(c) Applicability

    This AD applies to all The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 52, Doors.

(e) Unsafe Condition

    This AD was prompted by additional reports of fatigue cracking 
in the radius of the lower frames and in the lower number 5 cross 
beam of the forward cargo door. We are issuing this AD to prevent 
fatigue cracking of the lower corners of the door frame and number 5 
cross beam of the forward cargo door, which could result in rapid 
depressurization of the airplane.

(f) Compliance

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

(g) Retained High Frequency Eddy Current (HFEC) Initial/Repetitive 
Inspections

    This paragraph restates the requirements of paragraph (a) of AD 
2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000), with 
revised service information. Within 1 year or 4,500 flight cycles 
after May 16, 2000 (the effective date of AD 2000-07-06), whichever 
occurs later, perform an HFEC inspection to detect cracking of the 
lower corners (forward and aft) of the door frame of the forward 
cargo door, in accordance with Boeing 737 Nondestructive Test (NDT) 
Manual, D6-37239, Part 6, Section 51-00-00, Figure 4, dated August 
5, 1997, or April 5, 2007, or Figure 23, dated August 5, 1997 or 
April 5, 2004, as applicable.
    (1) If no cracking is detected, repeat the HFEC inspection 
thereafter at intervals not to exceed 4,500 flight cycles, until the 
requirements of paragraph (i) of this AD have been accomplished.
    (2) If any cracking is detected during any inspection required 
by paragraph (g) of this AD, prior to further flight, accomplish the 
requirements of paragraphs (g)(2)(i) and (g)(2)(ii) of this AD, 
which constitute terminating action for the repetitive inspections 
required by paragraph (g)(1) of this AD.
    (i) Accomplish the requirements of paragraph (g)(2)(i)(A) or 
(g)(2)(i)(B) of this AD, and install a cross beam repair and 
reinforcement modification of the cross beam, in accordance with 
Boeing Service Bulletin 737-52-1100, Revision 2, dated March 31, 
1994.
    (A) Repair the door frame of the forward cargo door in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate; or 
in accordance with data meeting the type certification basis of the 
airplane approved by the Boeing Commercial Airplanes Organization 
Designation Authorization (ODA) that has been authorized by the 
Manager, Seattle ACO, to make such findings. For a repair or 
modification method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, and paragraphs (g)(2)(ii), (h)(2), 
(h)(3)(ii), and (i)(2) of this AD, the Manager's approval letter 
must specifically reference this AD.
    (B) Replace the door frame of the forward cargo door with a new 
door frame, in accordance with Boeing Service Bulletin 737-52-1100, 
Revision 2, dated March 31, 1994.
    (ii) Modify the repaired or replaced door frame of the forward 
cargo door, in accordance with a method approved by the Manager, 
Seattle ACO, or in accordance with data meeting the type 
certification basis of the airplane approved by the Boeing 
Commercial Airplanes ODA that has been authorized by the Manager, 
Seattle ACO, to make those findings.

    Note 1 to paragraphs (g), (h), (i), and (j) of this AD: 
Accomplishment of Boeing Service Bulletin 737-52-1100, Revision 2, 
dated March 31, 1994, does not supersede the requirements of AD 90-
06-02, Amendment 39-6489 (55 FR 8372, March 7, 1990).

(h) Retained Initial Detailed Inspection and Repetitive Inspections

    This paragraph restates the requirements of paragraph (b) of AD 
2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000). Within 
1 year or 4,500 flight cycles after May 16, 2000 (the effective date 
of AD 2000-07-06), whichever occurs later, perform a detailed 
inspection to detect cracking of the cross beam (i.e., upper and 
lower chord and Web sections) of the forward cargo door, in 
accordance with Boeing Service Bulletin 737-52-1100, Revision 2, 
dated March 31, 1994. For the purposes of this AD, a detailed 
inspection is: ``An intensive examination of a specific item, 
installation, or assembly to detect damage, failure, or 
irregularity. Available lighting is normally supplemented with a 
direct source of good lighting at an intensity deemed appropriate. 
Inspection aids such as mirror, magnifying lenses, etc., may be 
necessary. Surface cleaning and elaborate procedures may be 
required.''
    (1) If no cracking is detected, repeat the inspection thereafter 
at intervals not to exceed 4,500 flight cycles until the 
requirements of paragraph (i) of this AD have been accomplished.
    (2) If any cracking is detected on the lower chord section of 
the cross beam during any inspection required by paragraph (h) of 
this AD, prior to further flight, repair in accordance with a method 
approved by the Manager, Seattle ACO, or in accordance with data 
meeting the type certification basis of the airplane approved by the 
Boeing Commercial Airplanes ODA that has been authorized by the 
Manager, Seattle ACO, to make those findings.
    (3) If any cracking is detected on any area excluding the lower 
chord section of the cross beam (i.e., upper chord and Web section) 
during any inspection required by paragraph (h) of this AD, prior to 
further flight, accomplish the requirements of paragraph (h)(3)(i) 
or (h)(3)(ii) of this AD, as applicable, which constitutes 
terminating action for the repetitive inspections required by 
paragraph (h)(1) of this AD.
    (i) For airplanes with line numbers 1 through 1231: Install a 
cross beam repair and preventative modification of the outboard 
radius of the lower corners (forward and aft) of the door frame, in 
accordance with Boeing Service Bulletin 737-52-1100, Revision 2, 
dated March 31, 1994.
    (ii) For airplanes with line numbers 1232 and subsequent: 
Install a cross beam repair and preventative modification of the 
outboard radius of the lower corners (forward and aft) of the door 
frame, in accordance with a method approved by the Manager, Seattle 
ACO, or in accordance with data meeting the type certification basis 
of the airplane approved by the Boeing Commercial Airplanes ODA that 
has been authorized by the Manager, Seattle ACO, to make those 
findings.

(i) Retained Terminating Action

    This paragraph restates the requirements of paragraph (c) of AD 
2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000), with 
revised service information. Within 4 years or 12,000 flight cycles 
after May 16, 2000 (the effective date of AD 2000-07-06), whichever 
occurs later: Install the preventative modification of the outboard 
radius of the lower corners (forward and aft) of the door frame and 
the reinforcement modification of the cross beam of the forward 
cargo door, in accordance with paragraph (i)(1) or (i)(2) of this 
AD, as applicable. Accomplishment of paragraph (i)(1) or (i)(2) of 
this AD, as applicable, constitutes terminating action for the 
repetitive inspections required by paragraphs (g)(1) and (h)(1) of 
this AD.
    (1) For airplanes with line numbers 1 through 1231: Accomplish 
the preventative modification and the reinforcement modification, in 
accordance with Boeing Service Bulletin 737-52-1100, Revision 2, 
dated March 31, 1994.
    (2) For airplanes with line numbers 1232 and subsequent: 
Accomplish the preventative modification and the reinforcement 
modification, in accordance with a method approved by the Manager, 
Seattle ACO, or in accordance with data meeting the type 
certification basis of the airplane approved by the Boeing 
Commercial Airplanes ODA that has been authorized by the Manager, 
Seattle ACO, to make those findings; or in accordance with Boeing 
Alert Service Bulletin 737-52A1100, Revision 5, dated February 14, 
2011. As of the effective date of this AD, use only Boeing Alert 
Service Bulletin 737-52A1100, Revision 5, dated

[[Page 50411]]

February 14, 2011, to accomplish the modifications required by this 
paragraph.

(j) Retained Action for Airplanes on Which Modifications Were 
Accomplished Previously

    This paragraph restates the requirements of paragraph (d) of AD 
2000-07-06, Amendment 39-11660 (65 FR 19302, April 11, 2000). For 
all airplanes on which modifications of the forward lower corner of 
the door frame and the cross beam of the forward cargo door were 
accomplished in accordance with Boeing Service Bulletin 737-52-1100, 
dated August 25, 1988, or Revision 1, dated July 20, 1989; or in 
accordance with the requirements of AD 90-06-02, Amendment 39-6489 
(55 FR 8372, March 7, 1990): Within 4 years or 12,000 flight cycles 
after May 16, 2000 (the effective date of AD 2000-07-06), whichever 
occurs later, install the reinforcement modification of the aft 
corner of the door frame of the forward cargo door, in accordance 
with Boeing Service Bulletin 737-52-1100, Revision 2, dated March 
31, 1994. Accomplishment of such modification constitutes 
terminating action for the repetitive inspections required by 
paragraphs (g)(1) and (h)(1) of this AD.

(k) New Inspections and Corrective Actions

    Except as provided by paragraphs (m)(1) and (m)(2) of this AD: 
At the applicable time specified in paragraph 1.E, ``Compliance,'' 
of Boeing Alert Service Bulletin 737-52A1100, Revision 5, dated 
February 14, 2011, do the inspections required by paragraphs (k)(1) 
and (k)(2) of this AD, as applicable. Do all applicable related 
investigative and corrective actions before further flight, in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-52A1100, Revision 5, dated February 14, 2011; 
except as required by paragraph (m)(3) of this AD. Accomplishment of 
the inspections required by paragraph (k) of this AD terminates the 
requirements of the repetitive inspections required by paragraphs 
(g)(1) and (h)(1) of this AD. If any cracking is found in the number 
4 cross beam, before further flight, repair in accordance with 
Boeing Special Attention Service Bulletin 737-52-1149, dated 
December 11, 2003.

    Note 2 to paragraph (k) of this AD: Boeing Alert Service 
Bulletin 737-52A1100, Revision 5, dated February 14, 2011, refers to 
Boeing Special Attention Service Bulletin 737-52-1149, dated 
December 11, 2003, as an additional source of guidance for the 
inspection for cracks of the number 4 cross beam.

    (1) For airplanes identified in Tables 1 and 2 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-52A1100, 
Revision 5, dated February 14, 2011: Do a one-time HFEC inspection 
of the applicable location for cracks, in accordance with the Work 
Instructions, Part I, of Boeing Alert Service Bulletin 737-52A1100, 
Revision 5, dated February 14, 2011.
    (2) For airplanes identified in Table 3 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-52A1100, 
Revision 5, dated February 14, 2011: Do a one-time general visual 
inspection of the reinforcement angle for excessive shimming or 
fastener pull-up, in accordance with the Work Instructions, Part 
III, of Boeing Alert Service Bulletin 737-52A1100, Revision 5, dated 
February 14, 2011.

(l) No Supplemental Structural Inspections Required by This AD

    (1) The supplemental structural inspections specified in Table 4 
of paragraph 1.E., ``Compliance,'' and Part 5 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-52A1100, Revision 
5, dated February 14, 2011, are not required by this AD.
    (2) The supplemental structural inspections specified in Table 4 
of paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-52A1100, Revision 5, dated February 14, 2011, may be used in 
support of compliance with section 121.1109(c)(2) or 129.109(c)(2) 
of the Federal Aviation Regulations (14 CFR 121.1109(c)(2) or 14 CFR 
129.109(c)(2)). The corresponding actions specified in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
52A1100, Revision 5, dated February 14, 2011, are not required by 
this AD.

(m) Exceptions to Certain Service Information

    (1) Where paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-52A1100, Revision 5, dated February 14, 2011, 
specifies a compliance time relative to the Revision 5 issue date of 
the service bulletin, this AD requires compliance within the 
specified compliance time after the effective date of this AD.
    (2) Where Table 1, ``Condition'' column of Paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-52A1100, 
Revision 5, dated February 14, 2011, specifies ``airplanes without 
either the repair or modification accomplished in accordance with 
previous releases of this service bulletin,'' the corresponding 
condition in this AD is for ``airplanes on which either a repair or 
modification was not accomplished before the effective date of this 
AD.''
    (3) Where Boeing Alert Service Bulletin 737-52A1100, Revision 5, 
dated February 14, 2011, specifies to contact Boeing for certain 
actions: Before further flight, do the repair using a method 
approved in accordance with the procedures specified in paragraph 
(n)(1) of this AD.

(n) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO, 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.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD if it is approved by the 
Boeing Commercial Airplanes ODA that has been authorized by the 
Manager, Seattle ACO to make those findings. 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.
    (4) AMOCs approved previously in accordance with AD 2000-07-06, 
Amendment 39-11660 (65 FR 19302, April 11, 2000), are approved as 
AMOCs for the corresponding requirements of this AD.

(o) Related Information

    (1) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone (425) 
917-6450; fax (425) 917-6590; email alan.pohl@faa.gov.
    (2) For 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; Internet https://www.myboeingfleet.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.

    Issued in Renton, Washington, on August 13, 2012.
John P. Piccola,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-20470 Filed 8-20-12; 8:45 am]
BILLING CODE 4910-13-P


