[Federal Register Volume 70, Number 186 (Tuesday, September 27, 2005)]
[Rules and Regulations]
[Pages 56361-56365]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-19143]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-18788; Directorate Identifier 2003-NM-203-AD; 
Amendment 39-14296; AD 2005-20-03]
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: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. This AD requires repetitive inspections of the intercostal 
webs, attachment clips, and stringer splice channels for cracks; and 
corrective action if necessary. This AD is prompted by reports of 
fatigue cracks on several Boeing Model 737-200 series airplanes. 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.

DATES: This AD becomes effective November 1, 2005.
    The incorporation by reference of a certain publication listed in 
the AD is approved by the Director of the Federal Register as of 
November 1, 2005.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    Docket: The AD docket contains the proposed AD, comments, and any 
final disposition. You can examine the AD docket on the Internet at 
http://dms.dot.gov, or in person at the Docket Management Facility 
office between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the U.S. 
Department of Transportation, 400 Seventh Street, SW., room PL-401, 
Washington, DC. This docket number is FAA-2005-18788; the directorate 
identifier for this docket is 2003-NM-203-AD.

FOR FURTHER INFORMATION CONTACT: Howard Hall, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6430; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with an AD for certain Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. That action, published in the Federal Register on 
August 6, 2004 (69 FR 47808), proposed to require repetitive 
inspections of the intercostal webs, attachment clips, and stringer 
splice channels for cracks; and corrective action if necessary.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
submitted on the proposed AD.

Qualified Support for the Proposed AD

    One commenter, an operator, stated that the proposed AD is 
acceptable provided that the service bulletin referenced in the 
proposed AD is corrected to reflect the proper work instructions and to 
reference accurate figures for accomplishment.
    The FAA cannot respond to the generality of the commenter's 
statement. However, other commenters have requested clarification on 
certain aspects of the work instructions and requested certain revision 
of the ``Costs of Compliance'' section of this AD. Those comments are 
specified and responded to in the appropriate paragraphs below.

Request for Clarification in Paragraph (k) of the Proposed AD

    Two commenters request that paragraph (k) be revised to clarify 
that the reference to using Figure 201 instead of Figure 202 of the 
service bulletin only applies to Model 737-400 series airplanes.
    We agree that paragraph (k) of the AD should be clarified and have 
revised the AD accordingly.

Request To Withdraw the Proposed AD

    One commenter, an operator, states that the Maintenance Planning 
Document (MPD) is the logical document to accomplish the main 
objectives of the inspections specified in the proposed AD. The 
commenter suggests that it makes more sense to revise MPD Task S53-22-
A-2, rather than to issue an AD. We infer that the commenter is 
requesting that the proposed AD be withdrawn.
    We do not agree. We are obligated by part 39 of the Federal 
Aviation Regulations (FAR) to appropriately address any identified 
unsafe condition that is likely to exist on other airplanes. The MPD is 
appropriate for addressing routine maintenance of critical structural 
components. However, operators may submit their specific and particular 
MPD task cards for consideration as an alternative method of compliance 
(AMOC) if they wish, in accordance with paragraph (n) of the AD. No 
change is necessary to the AD in this regard.

Request for More Information Regarding Paragraph (k) of the Proposed AD

    One commenter, an operator, requests that inspection specifics be 
added to paragraph (k) of the proposed AD for the stringer-16L (S-16L) 
area in the post-repair configuration. The commenter does not believe 
that Boeing Special Attention Service Bulletin 737-53-1204, dated June 
19, 2003, referenced in the proposed AD as the appropriate source of 
service information, provides sufficient inspection specifics in Figure 
1.
    The FAA does not agree that further inspection specifics are 
necessary to clarify paragraph (k) of the AD. Figure

[[Page 56362]]

1 does not specifically show the repair/modification configurations at 
S-16L, and is simply intended to show typical crack locations and to 
identify the structural components that require inspection. Since the 
general inspection details provided in Figure 1 are applicable to both 
pre- and post-repair/modification configurations, no change to the AD 
is necessary in this regard.

Request To Allow ``Credit'' for Certain Repairs

    One commenter, an operator, requests that repairs on the affected 
intercostals that are installed prior to the effective date of the AD 
be addressed. The operator states that the proposed AD specifies that 
certain repairs must be approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA; or per data meeting the type 
certification basis of the airplane approved by a Boeing Designated 
Engineering Representative (DER) who has been authorized by the 
Manager, Seattle ACO, to make such findings. The operator requests that 
the final rule allow credit for any repairs previously approved by the 
Seattle ACO.
    We do not agree that previous repairs need to be addressed other 
than through the normal process as stated above by the commenter. Other 
than the repairs already identified at S-16L, we are not aware of any 
specific pre-existing repair configurations that should be addressed in 
the final rule. The Manager, Seattle ACO, can approve design data for 
previously installed or newly installed repair configurations prior to 
the issuance of this AD. However, approval as an AMOC with the AD 
cannot be given until the date the final rule is effective. No change 
is necessary to the AD in this regard.

Requests To Address Previously Accomplished Modification/Repairs

    Two commenters, both operators, request that provision for 
``previous or newly accomplished'' installations of the repair be added 
to paragraph (k) of the proposed AD.
    We acknowledge the commenters' concern and partially agree. 
Paragraph (k) of the AD, as worded in the AD, simply permits deferring 
the repetitive inspections if the installation of the repair as a 
preventative modification or corrective action is accomplished in 
accordance with Part 1 of the Work Instructions of the service 
bulletin. We did not specify that installation of the repair must be 
performed either before or after the effective date of the AD, since, 
in this case, it does not matter when it is accomplished. No change is 
necessary to the AD in this regard.

Requests To Extend Initial Compliance Time of Paragraph (g) of the 
Proposed AD

    Several commenters request that the grace period specified in 
paragraph (g), ``4,500 flight cycles after the effective date of the 
AD,'' be extended to 7,500 or 8,000 flight cycles. One commenter states 
that the most critical area (STR 16L between Body Station (BS) 348.2 
and BS 360) can only be inspected correctly by accessing additional 
areas, which may include removing lavatories or galleys. The commenters 
contend that extending the grace period of the initial compliance time 
would allow most operators to accomplish the requirements of paragraph 
(g) during normal scheduled maintenance.
    We do not agree that the grace period should be extended beyond 
4,500 flight cycles. We have determined that the grace period of 4,500 
is appropriate and adequate to maintain an acceptable level of safety. 
The grace period represents more than two years of average operation, 
during which time most operators will have accomplished regularly 
schedule maintenance. The commenter has provided no technical data to 
show that extending the grace period compliance time to 7,500 or 8,000 
flight cycles would continue to provide an acceptable level of safety. 
However, under the provisions of paragraph (n) of the AD, we may 
consider requests for adjustments to the grace period for the initial 
compliance time if sufficient data are submitted to substantiate that 
such an extension of the grace period would provide an acceptable level 
of safety. No change is necessary to the AD in this regard.

Request To Extend Initial Compliance Time of Paragraph (g) of the 
Proposed AD for Certain Areas

    One commenter requests that, for areas that are non-critical, the 
compliance time be extended from 15,000 total flight cycles to 25,000 
total flight cycles. The commenter notes that it is not clear why the 
non-critical areas have the same initial threshold as the critical area 
(S-16L). The commenter contends that the compliance time should be 
extended for those areas other than S-16L.
    We do not agree. We have received recent service reports of cracked 
structure occurring at locations other than S-16L as early as 18,910 
total flight cycles. No change is necessary to the AD in this regard.

Request for Credit for Similar Inspections

    One commenter, an operator, notes that certain inspections similar 
to the inspections in the proposed AD are already required under the 
Corrosion Prevention and Control Program (CPCP). Although the commenter 
acknowledges that the intensity and type of inspection is not identical 
to the inspections specified in the proposed AD, the commenter requests 
that some relief of the compliance time should be considered if the 
CPCP inspections have been performed recently.
    We do not agree to extend the compliance time. In developing this 
AD, we considered the inspections of the baseline CPCP program, but 
also noted that certain operators may be using different CPCP programs. 
However, under the provisions of paragraph (n) of the AD, we may 
approve requests for adjustments to the compliance time if data are 
submitted to substantiate that such an adjustment would provide an 
acceptable level of safety. No change is necessary to the AD in this 
regard.

Request To Clarify the Failure Mechanism

    One commenter, an operator, requests that we explain why the FAA 
and the manufacturer disagree on the potential failure mechanism. The 
commenter points out that the manufacturer does not indicate that the 
fatigue cracking could result in loss of the forward entry door, only 
that incorporation of the service bulletin would prevent possible 
decompression and unscheduled down time.
    We acknowledge that the manufacturer's service bulletin does not 
specifically advise that ``loss of the forward entry door'' could occur 
as a result of the identified unsafe condition. However, the 
manufacturer and the FAA agree that several potential failure 
scenarios, such as loss of the forward entry door, could occur. Both 
the manufacturer and the FAA agree that an unsafe condition has been 
identified and is likely to exist or to develop in other airplanes. 
Therefore, the actions specified in the AD are necessary to detect and 
correct fatigue cracking of the intercostals of the forward entry door. 
No change is necessary to the AD in this regard.

Request To Revise the Costs of Compliance

    Several commenters request that the ``Costs of Compliance'' section 
be revised to reflect the number of work hours required for access.
    We do not agree that the cost estimate provided in the proposed AD 
should be revised. Based on the best data available, the manufacturer 
provided the number of work hours (two) necessary to do the required 
actions.

[[Page 56363]]

This number represents the time necessary to perform only the actions 
actually required by this AD. We recognize that, in doing the actions 
required by an AD, operators may incur incidental costs in addition to 
the direct costs. The cost analysis in AD rulemaking actions, however, 
typically does not include incidental costs such as the time required 
to gain access and close up, time necessary for planning, or time 
necessitated by other administrative actions. Those incidental costs, 
which may vary significantly among operators, are almost impossible to 
calculate. No change is necessary to the AD in this regard.

Request To Replace Parts Without FAA Approval

    One commenter, an operator, asks that allowance be made in 
paragraph (m) for the replacement of parts without the need to contact 
the FAA for approval.
    We do not agree with the commenter's request. Since the service 
bulletin referenced in this AD does not provide specific instructions 
for repair (replacing the parts), operators must perform the repair in 
accordance with a method approved as specified in paragraph (m) of this 
AD.

Explanation of Change Made to This AD

    Since the issuance of the proposed AD, Boeing has received a 
Delegation Option Authorization (DOA). We have revised this AD to 
delegate the authority to approve an alternative method of compliance 
for any repair required by this AD to the Authorized Representative for 
the Boeing DOA Organization rather than the Designated Engineering 
Representative.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been submitted, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    This AD will affect about 3,113 airplanes worldwide and 876 
airplanes of U.S. registry. The required actions will take about 2 work 
hours per airplane, at an average labor rate of $65 per work hour. 
Based on these figures, the estimated cost of the AD for U.S. operators 
is $113,880, or $130 per airplane, per inspection cycle.

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 AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); 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 AD. 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.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2005-20-03 Boeing: Amendment 39-14296. Docket No. FAA-2005-18788; 
Directorate Identifier 2003-NM-203-AD.

Effective Date

    (a) This AD becomes effective November 1, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model 737-100, -200, -200C, -300, -400, 
and -500 series airplanes, as identified in Boeing Special Attention 
Service Bulletin 737-53-1204, dated June 19, 2003; certificated in 
any category.

Unsafe Condition

    (d) This AD was prompted by reports of fatigue cracks on several 
Boeing Model 737-200 series airplanes. 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.

Service Bulletin Definition

    (f) The term ``service bulletin,'' as used in this AD, means 
Boeing Special Attention Service Bulletin 737-53-1204, dated June 
19, 2003.

Initial Compliance Time

    (g) 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 inspections specified in paragraph 
(h) or (i) of this AD, as applicable.

Inspection for Passenger Configuration Airplanes

    (h) For Group 1 passenger airplanes identified in the service 
bulletin: Perform a detailed inspection of the intercostal web, 
attachment clips, and stringer splice channels for cracks; and a 
high frequency eddy current inspection of the stringer splice 
channels, located forward and aft of the forward entry door, for 
cracks; per Parts 1 and 2 of the Work Instructions of the service 
bulletin.

Inspection for Cargo Configuration Airplanes

    (i) For Group 2 cargo airplanes identified in the service 
bulletin: Perform a detailed inspection of the intercostal webs and 
attachment clips located forward of the forward entry door for 
cracks, per Part 3 of the Work Instructions of the service bulletin.

[[Page 56364]]

Repetitive Inspections

    (j) If no crack is found during any inspection required by 
paragraph (h) or (i) of this AD, repeat the inspections in paragraph 
(h) or (i) of this AD at the applicable time specified in Table 1 of 
this AD, except as provided by paragraph (k) of this AD.

                                    Table 1.--Repetitive Inspection Interval
----------------------------------------------------------------------------------------------------------------
                                                                         Repeat inspections at intervals not to
Airplane group number in Service Bulletin   For intercostal location--                  exceed--
----------------------------------------------------------------------------------------------------------------
Group 1..................................  Stringer-16L (S-16L), from   4,500 flight cycles.
                                            Body Stringer 348.2 to BS
                                            360 (aft of door).
Group 1..................................  S-7L through S-15L, from BS  25,000 flight cycles.
                                            348.2 to BS 360 (aft of
                                            door).
Group 1 and 2............................  S-7L through S-16L, from BS  25,000 flight cycles.
                                            294.5 to BS 303.9 (forward
                                            of door).
----------------------------------------------------------------------------------------------------------------

Deferral of Certain Repetitive Inspections

    (k) For intercostal webs at S-16L from BS 348.2 to BS 360: 
Installation of the repair as a preventative modification or 
corrective action per Part 1 of the Work Instructions of the service 
bulletin defers the repetitive inspections to intervals not to 
exceed 25,000 flight cycles. For Model 737-400 series airplanes, use 
737-400 Structural Repair Manual (SRM) 53-10-04, Figure 201, instead 
of Figure 202.

Corrective Actions

    (l) If any crack is found during any inspection required by 
paragraph (h) or (i) of this AD, perform the actions specified in 
paragraphs (l)(1) through (l)(3) of Table 2 of this AD, as 
applicable. Repeat the inspections at the applicable time specified 
in Table 1 of this AD, except as provided by paragraph (k) of this 
AD.

                                          Table 2.--Corrective Actions
----------------------------------------------------------------------------------------------------------------
                                        If any crack is found        At intercostal
 During any inspection specified in--            in--                  location--        Before further flight--
----------------------------------------------------------------------------------------------------------------
(1) Part 1 of the Work Instructions    (i) The intercoastal     S-16L, from BS 348.2 to  Repair per Part 1 of
 of the service bulletin.               web.                     BS 360 (aft of door).    the Work Instructions
                                                                                          of the service
                                                                                          bulletin, except the
                                                                                          service bulletin
                                                                                          specifies to contact
                                                                                          Boeing for repair
                                                                                          instructions, before
                                                                                          further flight, do the
                                                                                          repair specified in
                                                                                          paragraph (m) of this
                                                                                          AD. Use 737-400 SRM 53-
                                                                                          10-04, Figure 201,
                                                                                          instead of Figure 202,
                                                                                          as applicable (see
                                                                                          Note 1).
                                       (ii) An attachment clip  S-16L, from BSDo 348.2   Do the repair specified
                                        or stringer splice       to BS 360 (aft of        in paragraph (m) of
                                        channel.                 door).                   this AD.
(2) Part 2 of the Work Instructions    An intercoastal web,     S-7L through S-16L,      Do the repair specified
 of the service bulletin.               attachment clip, or      from BS 294.5 to BS      in paragraph (m) of
                                        stringer splice          303.9 (forward of        this AD.
                                        channel.                 door); and S-7L
                                                                 through S-15L, from BS
                                                                 348.2 to BS 360 (aft
                                                                 of door).
(3) Part 3 of the Work Instructions    An intercoastal web or   S-7L through S-16L,      Do the repair specified
 of the service bulletin.               attachment clip.         from BS 294.5 to BS      in paragraph (m) of
                                                                 303.9 (forward of        this AD.
                                                                 door).
----------------------------------------------------------------------------------------------------------------


    Note 1:  The service bulletin specifies to repair any crack 
found at the S-16L intercostal (BS 348.2-360) on Boeing Model 737-
400 series airplanes per 737-400 SRM 53-10-04, Figure 202. Figure 
202 does not exist; the correct figure is 737-400 SRM 53-10-04, 
Figure 201.

Repair

    (m) At the time specified in Table 2 of this AD, repair per a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA; or per data meeting the type certification basis 
of the airplane approved an Authorized Representative for the Boeing 
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.

Alternative Methods of Compliance (AMOCs)

    (n)(1) The Manager, Seattle ACO, has the authority to approve 
AMOCs for this AD, if requested in accordance with the procedures 
found in 14 CFR 39.19.
    (2) An AMOC that provides an acceptable level of safety may be 
used for corrective actions per data meeting the type certification 
basis of the airplane approved by a Boeing DOA Organization AR who 
has been authorized by the Manager, Seattle ACO, to make those 
findings. For a repair method to be approved, the approval must 
specifically reference this AD.

Material Incorporated by Reference

    (o) You must use Boeing Special Attention Service Bulletin 737-
53-1204, dated June 19, 2003, to perform the actions that are 
required by this AD, unless the AD specifies otherwise. The Director 
of the Federal Register approves the incorporation by reference of 
this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
To get copies of the service information, contact Boeing Commercial 
Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. To view 
the AD docket, go to the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street SW., room PL-401, Nassif 
Building, Washington, DC. To review copies of the service 
information, go to the National Archives and Records Administration 
(NARA). For information on the availability of this material at the 
NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html html.


[[Page 56365]]


    Issued in Renton, Washington, on September 16, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-19143 Filed 9-26-05; 8:45 am]
BILLING CODE 4910-13-P