[Federal Register Volume 72, Number 177 (Thursday, September 13, 2007)]
[Proposed Rules]
[Pages 52314-52316]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-18049]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-29174; Directorate Identifier 2007-NM-125-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. This proposed AD would require repetitive inspections 
to detect cracking of the body station 303.9 frame, and corrective 
action if necessary. This proposed AD also provides for optional 
terminating action for the repetitive inspections. This proposed AD 
results from reports of cracks found at the cutout in the web of body 
station frame 303.9 inboard of stringer 16L. We are proposing this AD 
to detect and correct such cracking, which could prevent the left 
forward entry door from sealing correctly, and could cause in-flight 
decompression of the airplane.

DATES: We must receive comments on this proposed AD by October 29, 
2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     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.
     Fax: (202) 493-2251.
     Hand Delivery: Room W12-140 on the ground floor of the 
West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Howard Hall, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6430; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
29174; Directorate Identifier 2007-NM-125-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Operations office between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The 
Docket Operations office (telephone (800) 647-5527) is located on the 
ground floor of the West Building at the DOT street address stated in 
the ADDRESSES section. Comments will be available in the AD docket 
shortly after the Docket Management System receives them.

Discussion

    We have received reports of cracks found at the cutout in the web 
of the body station 303.9 frame inboard of stringer 16L on seven Boeing 
Model 737 ``classic'' airplanes. The cracks were found on airplanes 
that had accumulated between 37,562 and 64,000 total flight cycles. 
Such cracking, if not corrected, could prevent the left forward entry 
door from sealing correctly, and could cause in-flight decompression of 
the airplane.

Relevant Service Information

    We have reviewed two service bulletins related to this action. The 
service bulletins are similar but affect different groups of airplanes.
    Boeing Alert Service Bulletin 737-53A1188, Revision 2, dated May 9, 
2007, for certain Model 737-300, -400, and -500 series airplanes, 
describes the following actions:
     Repetitive high-frequency eddy current (HFEC) and detailed 
inspections to detect cracking in the station 303.9 web and doubler 
around the cutouts for door stop straps at stringers 15L and 16L.
     A repair/preventive change, which includes installing a 
new web, doubler, and stop fitting assemblies; changing the shape of 
the web cutout; and doing an eddy current inspection.
    Service Bulletin 737-53A1188 specifies a threshold for the initial 
inspection of 10,000 total flight cycles and a grace period of 2,250 
flight cycles.
    Boeing Alert Service Bulletin 737-53A1197, dated August 25, 2006, 
for certain Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes, describes the following actions:
     Repetitive ultrasound inspections of the slot-shaped 
cutout in the web for the door stop strap at stringer 16L.
     Repetitive HFEC inspections of the web along the upper 
edge and lower edge of the doubler around the doorstop strap at 
stringer 16L.
     Repetitive detailed inspections of the web around the 
doubler for the cutout at stringer 16.
     A repair/preventive change, which involves installing a 
new web and doubler.
    Service Bulletin 737-53A1197 specifies a threshold for the initial 
inspection of 30,000 total flight cycles and a grace period of 2,250 
flight cycles.
    For both service bulletins, a repair/preventive change eliminates 
the need

[[Page 52315]]

for the repetitive inspections. For airplanes on which the repair/
preventive change was previously done according to the original version 
or Revision 1 of Alert Service Bulletin 737-53A1188, replacing the 
existing kit with a new kit (in accordance with Revision 2) is 
necessary to eliminate the need for the repetitive inspections.
    Accomplishing the actions specified in the service bulletins is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed below.

Difference Between Proposed AD and Service Information

    The service bulletins specify 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:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.

Costs of Compliance

    There are about 2,765 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs, 
depending on airplane configuration, for U.S. operators to comply with 
this proposed AD.

                                                                     Estimated Costs
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                                                          Average
            Action                    Work hours         labor rate           Parts          Cost per airplane      Number of U.S.-        Fleet cost
                                                          per hour                                               registered airplanes
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Inspection....................  1 to 4................          $80  None..................  $80 to $320, per   1,154.................  $92,320 to
                                                                                              inspection cycle.                          $369,280, per
                                                                                                                                         inspection
                                                                                                                                         cycle.
Repair/preventive change, if    12 to 30..............           80  $564 to $2,236........  $1,524 to $4,636.  Up to 1,154...........  Up to
 done.                                                                                                                                   $5,349,944.
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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); and
    3. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-29174; Directorate Identifier 2007-NM-
125-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
29, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the airplanes, certificated in any 
category, identified in Table 1 of this AD.

                         Table 1.--Applicability
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                                          As identified in Boeing Alert
             Boeing model--                     Service Bulletin--
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737-100, -200, and -200C series          737-53A1197, dated August 25,
 airplanes.                               2006.
737-300, -400, and -500 series           737-53A1188, Revision 2, dated
 airplanes.                               May 9, 2007, or 737-53A1197,
                                          dated August 25, 2006.
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[[Page 52316]]

Unsafe Condition

    (d) This AD results from reports of cracks found at the cutout 
in the web of body station frame 303.9 inboard of stringer 16L. We 
are issuing this AD to detect and correct such cracking, which could 
prevent the left forward entry door from sealing correctly, and 
could cause in-flight decompression of the airplane.

Compliance

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

Repetitive Inspections: Service Bulletin 737-53A1188

    (f) For airplanes identified in Boeing Alert Service Bulletin 
737-53A1188, Revision 2, dated May 9, 2007, including airplanes 
modified by the repair/preventive change specified in the original 
version, dated April 9, 1998, or Revision 1, dated March 18, 1999, 
of the service bulletin: Do detailed and high frequency eddy current 
(HFEC) inspections in the web and doubler around the slotted holes 
in the frame web at stringers 15L and 16L, in accordance with the 
Accomplishment Instructions of the service bulletin. Do the 
inspections at the applicable time specified in paragraph 1.E. of 
the service bulletin, except as provided by paragraph (h) of this 
AD. Do all applicable corrective actions before further flight in 
accordance with the service bulletin, except as provided by 
paragraph (i) of this AD. Repeat the inspections at intervals not to 
exceed 4,500 flight cycles until accomplishment of the repair/
preventive change in accordance with the service bulletin, which 
terminates the repetitive inspection requirements. A repair/
preventive change done in accordance with the original version or 
Revision 1 of the service bulletin does not terminate the repetitive 
inspections, but the repetitive inspections may be terminated after 
the existing kit is replaced with a new kit in accordance with 
Revision 2 of the service bulletin, paragraph 3.B., Part II, step 3, 
or Part III, step 3.

Repetitive Inspections: Service Bulletin 737-53A1197

    (g) For airplanes identified in Boeing Alert Service Bulletin 
737-53A1197, dated August 25, 2006: Do an ultrasound inspection of 
the slot-shaped cutout in the web for the door stop strap at 
stringer 16L, an HFEC inspection of the web along the upper and 
lower edges of the doubler around the doorstop strap at stringer 
16L, and a detailed inspection of the web around the doubler for the 
cutout at stringer 16L, in accordance with the Accomplishment 
Instructions of the service bulletin. Do the inspections at the 
applicable time specified in paragraph 1.E. of the service bulletin, 
except as provided by paragraph (h) of this AD. Do all applicable 
corrective actions before further flight in accordance with the 
service bulletin, except as provided by paragraph (i) of this AD. 
Repeat the inspections at intervals not to exceed 4,500 flight 
cycles, until accomplishment of the repair/preventive change in 
accordance with the service bulletin, which terminates the 
repetitive inspections.

Exceptions to Service Bulletin Specifications

    (h) Where Boeing Alert Service Bulletin 737-53A1188, Revision 2, 
dated May 9, 2007; and Boeing Alert Service Bulletin 737-53A1197, 
dated August 25, 2006, specify a compliance time after release of 
the service bulletin, this AD requires compliance within the 
specified time after the effective date of this AD.
    (i) Where Boeing Alert Service Bulletin 737-53A1188, Revision 2, 
dated May 9, 2007; and Boeing Alert Service Bulletin 737-53A1197, 
dated August 25, 2006, specify to contact Boeing for appropriate 
action, including repair of damage outside the scope of the service 
bulletin, repair using a method approved in accordance with the 
procedures specified in paragraph (j) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (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 an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who 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.

    Issued in Renton, Washington, on August 31, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-18049 Filed 9-12-07; 8:45 am]
BILLING CODE 4910-13-P