
[Federal Register Volume 76, Number 170 (Thursday, September 1, 2011)]
[Proposed Rules]
[Pages 54399-54403]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-22370]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0914; Directorate Identifier 2010-NM-166-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model 737-200, -
200C, -300, -400, and -500 Series 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 certain Model 737-300,

[[Page 54400]]

-400, and -500 series airplanes. The existing AD currently requires 
repetitive external non-destructive inspections to detect cracks in the 
fuselage skin along the chem-mill step at stringers S-1 and S-2 right, 
between station (STA) 827 and STA 847, and repair if necessary. Since 
we issued that AD, we have received reports of additional crack 
findings of the fuselage crown skin at the chem-milled steps. This 
proposed AD would add inspections for cracking in additional fuselage 
crown skin locations, and repair if necessary. This proposed AD would 
also reduce the inspection thresholds for certain airplanes, extend 
certain repetitive inspection intervals, and add airplanes to the 
applicability of the existing AD. We are proposing this AD to detect 
and correct fatigue cracking of the fuselage skin panels at the chem-
milled steps, which could result in sudden fracture and failure of the 
fuselage skin panels, and consequent rapid decompression of the 
airplane.

DATES: We must receive comments on this proposed AD by October 17, 
2011.

ADDRESSES: You may send comments 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; e-mail me.boecom@boeing.com; 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.

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: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: 425-917-
6447; fax: 425-917-6590; e-mail: wayne.lockett@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-2011-0914; 
Directorate Identifier 2010-NM-166-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 December 21, 2009, we issued AD 2010-01-09, Amendment 39-16167 
(75 FR 1527, January 12, 2010), for certain Model 737-300, -400, and -
500 series airplanes. That AD requires repetitive external non-
destructive inspections to detect cracks in the fuselage skin along the 
chem-mill step at stringers S-1 and S-2 right, between STA 827 and STA 
847, and repair if necessary. That AD resulted from a report of a hole 
in the fuselage skin common to stringers S-1 and S-2 left, between STA 
827 and STA 847, on an airplane that diverted to an alternate airport 
due to cabin depressurization and subsequent deployment of the oxygen 
masks. We issued that AD to detect and correct fatigue cracking of the 
fuselage skin panels at the chem-milled steps, which could result in 
sudden fracture and failure of the fuselage skin panels, and consequent 
rapid decompression of the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2010-01-09, we have received reports of new 
findings of cracking in the fuselage crown skin at the horizontal chem-
milled steps at locations between body stations 259.5 and 1016 and 
between stringers S-10L and S-10R. The cause of the cracking is under 
investigation.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1301, Revision 2, 
dated April 25, 2011. Boeing Alert Service Bulletin 737-53A1301, dated 
September 3, 2009, was referred to for accomplishing the actions in the 
existing AD. We also reviewed Boeing Alert Service Bulletin 737-
53A1301, Revision 1, dated June 7, 2010. Revision 1 of this service 
bulletin adds inspections for cracking in additional fuselage crown 
skin locations, and repair if necessary; it reduces the inspection 
threshold for certain airplanes; extends certain repetitive inspection 
intervals; and adds airplanes to the effectivity (Model 737-200 and -
200C series airplanes, and Model 737-300, -400, and -500 series without 
ELT antenna provisions). The new inspection types specified in Revision 
1 of this service bulletin are detailed inspections, and optional 
external nondestructive: ultrasonic phased array inspections. Revision 
1 of this service bulletin also recommends contacting Boeing for 
inspection instructions for Group 26 airplanes. Revision 2 of this 
service bulletin specifies that no more work is necessary on airplanes 
changed as specified in Revision 1 of this service bulletin. Revision 2 
of this service bulletin only includes minor editorial changes.
    Boeing Alert Service Bulletin 737-53A1301, Revision 2, dated April 
25, 2011; and Boeing Alert Service Bulletin 737-53A1301, Revision 1, 
dated June 7, 2010; specify that the compliance times for the initial 
inspections for Groups 2, 8, and 10 airplanes at the ELT antenna 
provision at stringers S-1 and S-2R between BS 827 and BS 847, are at 
the latest of the following: Prior to the accumulation of 35,000 total 
flight cycles, or, depending on inspection locations, within 1,800 
flight cycles after the issue date of the original issue or Revision 1 
of this service bulletin, or within 1,800 flight cycles after the most 
recent inspection done in accordance with Boeing Alert Service Bulletin 
737-53A1301, dated September 3, 2009. For Groups 1 through 12 
airplanes, at the new inspection locations, the compliance times are 
prior to the accumulation of 35,000 total flight

[[Page 54401]]

cycles, or within 1,800 flight cycles after the issue date of Revision 
1 of this service bulletin. For groups 1 through 12, the repetitive 
inspection interval is 1,800 flight cycles (for Option 1 inspections) 
and 2,400 flight cycles (for Option 2 inspections). For airplanes on 
which the inspection procedure is changed from Option 2 to Option 1, 
the first Option 1 inspection must be done within 2,400 flight cycles 
after doing the Option 2 inspection. For airplanes on which the 
inspection procedure is changed from Option 1 to Option 2, the first 
two Option 2 inspections must be done within 1,800 flight cycles.
    Boeing Alert Service Bulletin 737-53A1301, Revision 2, dated April 
25, 2011; specifies that the compliance times for the initial 
inspections for Groups 13 through 18 and 21 through 25 airplanes at the 
ELT antenna provision at stringers S-1 and S-2R, between BS 827 and BS 
847, are as follows:
     For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1301, dated September 3, 2009; or 
Revision 1, dated June 7, 2010; have been done: At the latest of the 
following, prior to the accumulation of 33,000 total flight cycles, or 
within 500 flight cycles after the most recent inspection done in 
accordance with Boeing Alert Service Bulletin 737-53A1301, dated 
September 3, 2009; or Revision 1, dated June 7, 2010.
     For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1301, dated September 3, 2009; or 
Revision 1, dated June 7, 2010; have not been done: Prior to the 
accumulation of 33,000 total flight cycles, or within 500 flight cycles 
after the issue date of Revision 2 of this service bulletin, whichever 
occurs later.
    For Groups 13 through 25, Boeing Alert Service Bulletin 737-
53A1301, Revision 2, dated April 25, 2011; specifies that the 
compliance times for the initial inspections for Groups 13 through 25 
airplanes at the new inspection locations are as follows: Prior to the 
accumulation of 33,000 total flight cycles, or within 500 flight cycles 
after the issue date of Revision 1 of Boeing Alert Service Bulletin 
737-53A1301, whichever occurs later.
    For Groups 13 through 25, Boeing Alert Service Bulletin 737-
53A1301, Revision 2, dated April 25, 2011; specifies that the 
repetitive inspection interval is 500 flight cycles (for Option 1) and 
1,000 flight cycles (for Option 2). For airplanes on which the 
inspection procedure is changed from Option 2 to Option 1, the first 
Option 1 inspection must be done within 1,000 flight cycles after doing 
the Option 2 inspection. For airplanes on which the inspection 
procedure is changed from Option 1 to Option 2, the first two Option 2 
inspections must be done within 500 flight cycles.
    For Group 26 airplanes, Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, specifies contacting Boeing to obtain 
engineering and accomplishment instructions for certain inspections.

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 the same type design.

Proposed AD Requirements

    This proposed AD would retain the requirements of AD 2010-01-09, 
and would add inspections for cracking in additional fuselage crown 
skin locations, and repair if necessary. This proposed AD would also 
reduce the inspection thresholds for certain airplanes, extend certain 
repetitive inspection intervals, and add airplanes to the applicability 
of AD 2010-01-09. This proposed AD would require accomplishing the 
actions specified in the service information described previously.

Interim Action

    We consider this proposed AD interim action. If final action is 
later identified, we might consider further rulemaking then.

Costs of Compliance

    We estimate that this proposed AD affects 654 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action                Work hours     Average labor      Cost per       registered       Fleet cost
                                                 rate per hour      product         airplanes
----------------------------------------------------------------------------------------------------------------
Inspection in AD 2010-01-09..  2..............             $85  $170 per                    135  $22,950 per
                                                                 inspection                       inspection
                                                                 cycle.                           cycle.
New inspection in this         Between 2 and                85  Between $170                654  Between
 proposed AD.                   30.                              and $2,550 per                   $111,180 and
                                                                 inspection                       $1,667,700 per
                                                                 cycle.                           inspection
                                                                                                  cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
a cost estimate for the on-condition actions 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

[[Page 54402]]

    (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) 2010-01-09, Amendment 39-16167 (75 FR 1527, January 12, 2010), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2011-0914; Directorate Identifier 
2010-NM-166-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
17, 2011.

Affected ADs

    (b) This AD supersedes AD 2010-01-09, Amendment 39-16167.

Applicability

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

Subject

    (d) Joint Aircraft System Component (JASC)/Air Transport 
Association (ATA) of America Code 53, Fuselage.

Unsafe Condition

    (e) This AD was prompted by reports of additional crack findings 
of the fuselage crown skin at the chem-milled steps. We are issuing 
this AD to detect and correct fatigue cracking of the fuselage skin 
panels at the chem-milled steps, which could result in sudden 
fracture and failure of the fuselage skin panels, and consequent 
rapid decompression of the airplane.

Compliance

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

Restatement of Requirements of AD 2010-01-09, Amendment 39-16167

Initial and Repetitive Inspections

    (g) For airplanes identified in Boeing Alert Service Bulletin 
737-53A1301, dated September 3, 2009: Before the accumulation of 
35,000 total flight cycles, or within 500 flight cycles after 
February 16, 2010 (the effective date of AD 2010-01-09), whichever 
occurs later, except as provided by paragraph (i) of this AD, do an 
external non-destructive inspection (NDI) to detect cracks in the 
fuselage skin along the chem-mill steps at stringers S-1 and S-2 
right, between station (STA) 827 and STA 847, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1301, dated September 3, 2009; or Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011. If no cracking is 
found, repeat the inspection thereafter at intervals not to exceed 
500 flight cycles; except as provided by paragraphs (i) and (n) of 
this AD. Accomplishing the inspections required by paragraph (j) of 
this AD terminates the inspections required by this paragraph.

Repair

    (h) If any crack is found during any inspection required by 
paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-
53A1301, dated September 3, 2009; or Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011; specifies to contact 
Boeing for repair instructions: Before further flight, repair the 
crack using a method approved in accordance with the procedures 
specified in paragraph (q) of this AD.

Optional Terminating Action for Repetitive Inspections in Paragraph (g) 
of This AD

    (i) Installing an external repair doubler along the chem-milled 
steps at stringers S-1 and S-2 right, between STA 827 and STA 847, 
constitutes terminating action for the repetitive inspections 
required by paragraph (g) of this AD for the repaired area only, 
provided all of the conditions specified in paragraphs (i)(1), 
(i)(2), and (i)(3) of this AD are met.
    (1) The repair is installed after September 3, 2009;
    (2) The repair was approved by the FAA or by a Boeing Company 
Authorized Representative or the Boeing Commercial Airplanes 
Organization Designation Authorization (ODA) that has been 
authorized by the Manager, Seattle Aircraft Certification Office 
(ACO) to make such findings; and
    (3) The repair extends a minimum of three rows of fasteners on 
each side of the chem-mill line in the circumferential direction.

New Inspections Including Additional Locations and Reduced Inspection 
Intervals

Groups 1 Through 25: Initial and Repetitive Inspections

    (j) For Groups 1 through 25 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1301, Revision 2, dated April 25, 2011: 
Except as provided by paragraph (k) of this AD, at the applicable 
time specified in paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1301, Revision 2, dated April 25, 2011, do 
the applicable inspections required by paragraphs (j)(1) and (j)(2) 
of this AD, in accordance with paragraphs 3.B.1 through 3.B.25 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011. If no cracking is 
found, repeat the applicable inspections thereafter at the 
applicable intervals specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 737-53A1301, Revision 2, dated April 
25, 2011; except as provided by paragraphs (m) and (n) of this AD. 
Doing the inspections required by this paragraph terminates the 
inspections required by paragraph (g) of this AD.
    (1) For Groups 2, 8, 10, 13 through 18, and 21 through 25 
airplanes: Do a detailed inspection and an external non-destructive 
inspection (NDI) (medium frequency eddy current inspection, magneto 
optical imaging inspection, c-scan inspection, or ultrasonic phased 
array inspection) for cracking in the fuselage skin at the chem-mill 
steps at S-1 and S-2R between STA 827 and STA 847, as identified in 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011.
    (2) For Groups 1 through 25 airplanes: Do a detailed inspection 
and an external NDI (medium frequency eddy current inspection; 
magneto optical imaging inspection, c-scan inspection, or ultrasonic 
phased array inspection) for cracking in the fuselage skin at the 
chem-mill steps at the specified locations other than at S-1 and S-
2R between STA 827 and STA 847, as identified in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1301, Revision 
2, dated April 25, 2011.


    Note 1: Option 1 of Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, specifies a detailed inspection, 
and one additional inspection (external NDI, medium frequency eddy 
current inspection, magneto optical imaging inspection, or c-scan 
inspection). Option 2 specifies a detailed inspection and an 
external ultrasonic phased array inspection. These options have 
different compliance times after the initial inspection.


    (k) Where Boeing Alert Service Bulletin 737-53A1301, Revision 2, 
dated April 25, 2011, specifies a compliance time after ``the date 
of Revision 1,'' or ``the date of Revision 2'' of that service 
bulletin, this AD requires compliance within the specified time 
after the effective date of this AD.

Repair

    (l) If any crack is found during any inspection required by 
paragraph (j) of this AD: Before further flight, repair the crack 
using a method approved in accordance with the procedures specified 
in paragraph (q) of this AD. Doing the repair ends the repetitive 
inspections required by paragraph (j) for the repaired area only.

Optional Terminating Action for Repetitive Inspections

    (m) Installing an external repair doubler along the chem-milled 
steps at any location identified in Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011, constitutes 
terminating action for the repetitive inspections required by 
paragraph (j) of this AD for the repaired area only, provided all of 
the conditions specified in

[[Page 54403]]

paragraphs (m)(1), (m)(2), and (m)(3) of this AD are met.
    (1) The repair is installed after the applicable date specified 
in paragraph (m)(1)(i) and (m)(1)(ii) of this AD.
    (i) For repairs at S-1 and S-2R between STA 827 and STA 847: 
Installed after September 3, 2009.
    (ii) For repairs at locations other than at S-1 and S-2R between 
STA 827 and STA 847: Installed after June 7, 2010.
    (2) The repair was approved by the FAA or by a Boeing Company 
Authorized Representative or the Boeing Commercial Airplanes 
Organization Designation Authorization (ODA) that has been 
authorized by the Manager, Seattle Aircraft Certification Office 
(ACO) to make such findings; and
    (3) The repair extends a minimum of three rows of fasteners on 
each side of the chem-mill line in the circumferential direction.
    (n) Accomplishing a modification of the chem-milled steps at any 
location identified in Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, using a method approved in 
accordance with the procedures specified in paragraph (q)(1) of this 
AD, terminates the repetitive inspections required by paragraphs (g) 
and (j) of this AD for the modified area only.

Group 26 Airplanes

    (o) For Group 26 airplanes identified in Boeing Alert Service 
Bulletin 737-53A1301, Revision 2, dated April 25, 2011: Within 1,800 
flight cycles after the effective date of this AD, accomplish 
applicable inspections and corrective action, as identified in the 
service bulletin, using a method approved in accordance with the 
procedures specified in paragraph (q)(1) of this AD.

Credit for Actions Accomplished in Accordance With Previous Service 
Information

    (p) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 737-53A1301, Revision 
1, dated June 7, 2010, are acceptable for compliance with the 
corresponding requirements of this AD.

Alternative Methods of Compliance (AMOCs)

    (q)(1) The Manager, Seattle 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 e-mailed 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.

Related Information

    (r) For more information about this AD, contact Wayne Lockett, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 
98057-3356; phone: 425-917-6447; fax: 425-917-6590; e-mail: 
wayne.lockett@faa.gov.
    (s) 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; e-mail 
me.boecom@boeing.com; 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 25, 2011.
Ali Bahrami,
Manager Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2011-22370 Filed 8-31-11; 8:45 am]
BILLING CODE 4910-13-P


