[Federal Register: November 17, 2008 (Volume 73, Number 222)]
[Proposed Rules]
[Page 67815-67817]
[DOCID:fr17no08-29]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

 [Docket No. FAA-2008-1213; Directorate Identifier 2007-NM-092-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 supersede an existing airworthiness
directive (AD) that applies to certain Boeing Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes. The existing AD currently
requires repetitive inspections of the intercostal webs, attachment
clips, and stringer splice channels for cracks; and corrective action
if necessary. This proposed AD would reduce the repetitive inspection
intervals from 25,000 flight cycles to 6,000 flight cycles, and expand
the inspection area for Model 737-200C series airplanes to include the
area aft of the forward entry door. This proposed AD results from
additional reports of fatigue cracks. We are proposing this AD to
detect and correct fatigue cracking of the intercostals on the forward
and aft sides of the forward entry door, which could result in loss of
the forward entry door and rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by January 2, 2009.

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:<PHONE_NUMBER>.
     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: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590, 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, P.O. Box 3707, Seattle, Washington 98124-2207.

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 (telephone<PHONE_NUMBER>) is in the
ADDRESSES section. Comments will be available in the AD docket shortly
after receipt.

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<PHONE_NUMBER>.

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-2008-1213;
Directorate Identifier 2007-NM-092-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 September 16, 2005, we issued AD 2005-20-03, amendment 39-14296
(70 FR 56361, September 27, 2005) for certain Boeing Model 737-100, -
200, -200C, -300, -400, and -500 series airplanes. That AD requires
repetitive inspections of the intercostal webs, attachment clips, and
stringer splice channels for cracks; and corrective action if
necessary. That AD resulted from reports of fatigue cracks on several
Boeing Model 737-200 series airplanes. We issued that AD to detect and
correct fatigue cracking of the intercostals on the forward and aft
sides of the forward entry door, which could result in loss of the
forward entry door and rapid decompression of the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2005-20-03, many operators have reported to
Boeing over one hundred fatigue cracks at all doorstop and hinge
support intercostals on both the forward and aft sides of the forward
entry door. Operators have also reported cracks on several airplanes at
multiple intercostal locations.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-53A1204,
Revision 1, dated March 26, 2007. We referred to Boeing Special
Attention Service Bulletin 737-53-1204, dated June 19, 2003, as the
appropriate source of service information for accomplishing the actions
required by AD 2005-20-03. Revision 1 reduces the repetitive inspection
intervals from 25,000 flight cycles to 6,000 flight cycles for all
areas.
    Revision 1 also adds a new inspection for cracking in the
intercostal area aft of the forward entry door for Boeing Model 737-
200C series airplanes on which the intercostals on the aft side of the
forward entry door were not inspected previously. (The original issue
of the

service bulletin specified inspections only of the forward area.)
    The compliance thresholds aft of the door vary depending on whether
actions have been previously accomplished in accordance with Part 1,
Part 2, and Part 3 of Paragraph 3.B. of Boeing Special Attention
Service Bulletin 737-53-1204, dated June 19, 2003.
     For airplanes on which the actions have been accomplished
previously, the threshold specified in the service bulletin for the
next corresponding action is 6,000 flight cycles after the date of the
previous inspection, or 3,000 flight cycles after March 26, 2007 (the
date of Revision 1 of the service bulletin), whichever occurs later.
     For airplanes on which the actions have not been
accomplished previously, the threshold specified in the service
bulletin for the initial inspection is 15,000 total flight cycles, or
within 4,500 flight cycles from June 19, 2003 (the date of the initial
release of the service bulletin), whichever occurs later.
     For all airplanes, the threshold for the initial
inspection specified in Part 4 of Paragraph 3.B. of Revision 1 of the
service bulletin is 15,000 total flight cycles, or within 4,500 flight
cycles from March 26, 2007.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an
unsafe condition that is likely to develop on other airplanes of the
same type design. For this reason, we are proposing this AD, which
would supersede AD 2005-20-03 and would retain the requirements of the
existing AD. This proposed AD would also reduce the repetitive
inspection intervals from 25,000 flight cycles to 6,000 flight cycles,
and expand the inspection area for Boeing Model 737-200C series
airplanes. This proposed AD would require accomplishing the actions
specified in the service bulletin described previously, except as
discussed under ``Difference Between the Proposed AD and the Service
Bulletin.''

Difference Between the Proposed AD and the Service Bulletin

    The service bulletin 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:
     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 3,132 airplanes of the affected design in the
worldwide fleet. The following table provides the estimated costs for
U.S. operators to comply with this proposed AD.

                                                 Estimated Costs
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                                                                                Number of
                                                 Average                            U.S.-
             Action                Work hours   labor rate   Cost per airplane    registered      Fleet cost
                                                 per hour                         airplanes
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 Inspection of areas forward of             2          $80   $160 per                    876   $140,160 per
 the aft entry door (required by                             inspection cycle.                 inspection cycle.
 AD 2005-20-03).
 Inspection of areas aft of the             1           80   $80 per inspection           19   $1,520 per
 forward entry door for Model                                cycle.                            inspection cycle.
 737-200C series airplanes (new
 proposed action).
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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, 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by
removing amendment 39-14296 (70 FR 56361, September 27, 2005) and
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-1213; Directorate Identifier 2007-NM-
092-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January
2, 2009.

Affected ADs

    (b) This AD supersedes AD 2005-20-03.

Applicability

    (c) This AD applies to Model 737-100, -200, -200C, -300, -400,
and -500 series airplanes, certificated in any category, as
identified in Boeing Alert Service Bulletin 737-53A1204, Revision 1,
dated March 26, 2007.

Unsafe Condition

    (d) This AD results from reports of fatigue cracks. We are
issuing this AD to detect and correct fatigue cracking of the
intercostals on the forward and aft sides of the forward entry door,
which could result in loss of the forward entry door and rapid
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.

Initial Compliance Time

    (f) For all Model 737-100, -200, -200C, -300, -400, and -500
series airplanes: Before the accumulation of 15,000 total flight
cycles, or within 4,500 flight cycles after November 1, 2005 (the
effective date of AD 2005-20-03), whichever occurs later: Do the
inspections required by paragraphs (h) and (i) of this AD.
    (g) For all Model 737-200C series airplanes: Before the
accumulation of 15,000 total flight cycles, or within 4,500 flight
cycles after the effective date of this AD, whichever occurs later:
Do the inspection required by paragraph (j) of this AD.

Initial Inspection for Passenger Configuration Airplanes

    (h) For Group 1 passenger airplanes identified in Boeing Alert
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007:
Perform a detailed inspection for cracking of the intercostal web,
attachment clips, and stringer splice channels; and a high frequency
eddy current inspection for cracking of the stringer splice channels
located forward and aft of the forward entry door; and do all
applicable corrective actions before further flight; in accordance
with Parts 1 and 2 of the Work Instructions of Boeing Special
Attention Service Bulletin 737-53-1204, dated June 19, 2003; or
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March
26, 2007. After the effective date of this AD, only Revision 1 may
be used.

Initial Inspection for Cargo Configuration Airplanes (Forward of the
Forward Entry Door)

    (i) For Group 2 cargo airplanes identified in Boeing Alert
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007:
Perform a detailed inspection for cracking of the intercostal webs
and attachment clips located forward of the forward entry door; and
do all applicable corrective actions before further flight; in
accordance with Part 3 of the Work Instructions of Boeing Special
Attention Service Bulletin 737-53-1204, dated June 19, 2003, or
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March
26, 2007. After the effective date of this AD, only Revision 1 may
be used.

Initial Inspection for Cargo Configuration Airplanes (Aft of the
Forward Entry Door)

    (j) For Group 2 cargo airplanes identified in Boeing Alert
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007:
Perform a detailed inspection for cracking of the intercostal webs
and attachment clips located aft of the forward entry door; and do
all applicable corrective actions before further flight; in
accordance with Part 4 of the Work Instructions of Boeing Special
Attention Service Bulletin 737-53-1204, dated June 19, 2003; or
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March
26, 2007. After the effective date of this AD, only Revision 1 may
be used.

Repeat Inspections

    (k) Repeat the inspections required by paragraphs (h), (i), and
(j) of this AD thereafter at intervals not to exceed 6,000 flight
cycles after the previous inspection, or within 3,000 flight cycles
after the effective date of this AD, whichever occurs later.

Exceptions

    (l) Do the actions required by this AD by accomplishing all the
applicable actions specified in the Accomplishment Instructions of
the Boeing Special Attention Service Bulletin 737-53-1204, dated
June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204,
Revision 1, dated March 26, 2007; (``the service bulletins'') except
as provided by paragraphs (l)(1) and (l)(2) of this AD. After the
effective date of this AD, only Revision 1 may be used
    (1) Where the service bulletins specify to contact Boeing for
repair instructions: Before further flight, repair using a method
approved in accordance with the procedures specified in paragraph
(m) of this AD.
    (2) Where the service bulletins specify a compliance time
relative to the date of a service bulletin, this AD requires
compliance relative to the effective date of this AD. Where the
service bulletins specify a compliance time relative to the date of
the initial release of the service bulletin, this AD requires
compliance relative to the effective date of AD 2005-20-03 (November
1, 2005).

Alternative Methods of Compliance (AMOCs)

    (m)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, ATTN: Howard Hall, Aerospace Engineer, Airframe Branch, ANM-
120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington
98057-3356; telephone<PHONE_NUMBER>; fax<PHONE_NUMBER>; has the
authority to approve AMOCs for this AD, if requested using 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.
    (4) AMOCs approved previously in accordance with AD 2005-20-03
are approved as AMOCs for the corresponding provisions of this AD,
provided the repetitive inspection intervals (if any) do not exceed
6,000 flight cycles.
    (5) AMOCs approved previously in accordance with AD 2005-20-03
are not approved as AMOCs for the provisions of paragraph (j) or (k)
of this AD.

    Issued in Renton, Washington, on November 6, 2008.
Stephen P. Boyd,
Assistant Manager, Transport Airplane Directorate, Aircraft
Certification Service.
[FR Doc. E8-27163 Filed 11-14-08; 8:45 am]

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