[Federal Register Volume 73, Number 131 (Tuesday, July 8, 2008)]
[Rules and Regulations]
[Pages 38905-38908]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-14471]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0184; Directorate Identifier 2007-NM-140-AD; 
Amendment 39-15575; AD 2008-13-12]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. This AD requires various repetitive inspections for cracking 
of the upper frame to side frame splice of the fuselage, and other 
specified and corrective actions if necessary. This AD also provides 
for an optional preventive modification, which terminates the 
repetitive inspections. This AD results from a report that the upper 
frame of the fuselage was severed between stringers S-13L and S-14L at 
station 747, and the adjacent frame at station 767 had a 1.3-inch-long 
crack at the same stringer location. We are issuing this AD to detect 
and correct fatigue cracking of the upper frame to side frame splice of 
the fuselage, which could result in reduced structural integrity of the 
frame and adjacent lap joint. This reduced structural integrity can 
increase loading in the fuselage skin, which will accelerate skin crack 
growth and result in decompression of the airplane.

DATES: This AD is effective August 12, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of August 12, 
2008.

ADDRESSES: 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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (telephone 800-647-5527) is the Document Management 
Facility, U.S. Department of Transportation, Docket Operations, M-30, 
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

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; telephone (425) 
917-6447; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. That NPRM was published in the Federal Register on November 
13, 2007 (72 FR 63831). That NPRM proposed to require various 
repetitive inspections for cracking of the upper frame to side frame 
splice of the fuselage, and other specified and corrective actions if 
necessary. That NPRM also provides for an optional preventive 
modification, which would terminate the repetitive inspections.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received.

Requests To Clarify Certain Paragraphs

    Boeing, Southwest Airlines (SWA), United Airlines (UA), and the Air 
Transport Association (ATA) on behalf of its member UA, ask that 
certain language in certain paragraphs of the NPRM be clarified, as 
follows:
    Boeing states that the intent of paragraph (h) of the NPRM is 
unclear, and the conditional statement could be misinterpreted. Boeing 
notes that the statement ``the structure that has been damaged is not 
covered in the structural repair manual'' (SRM) will likely be 
interpreted differently by each airline. Boeing adds that this frame 
area is relatively complex with a frame splice, stringer clips, and, in 
some cases, a shear tie in the area of the repair. Boeing states that 
only specific SRM repairs can be used to fix the frame in this complex 
area; for that reason, the referenced service bulletin specifically 
lists the SRM sections that can be used, and recommends contacting 
Boeing if the existing repairs are not per these sections. Boeing notes 
that there are other frames and general formed section repairs in the 
SRM that operators could have used that may or may not work for this 
area; for those cases or others that may not have been repaired in 
accordance with the SRM, Boeing would like to evaluate them for 
structural adequacy. Boeing believes the intent of paragraph (h) is to 
cover this situation, except to refer to paragraph (j) of the NPRM 
instead of contacting Boeing. Boeing recommends that paragraph (h) be 
rewritten as follows: ``If during the accomplishment of the corrective 
actions required by paragraph (f) of this AD, for airplanes for which a 
repair has previously been accomplished, if the repair is not per the 
737-400 SRM 53-00-07, Figure 201, Repair 1, or 737-500 SRM 53-00-07, 
Figure 201, Repair 1, or 737-300 SRM 53-00-07, Figure 201, Repair 1, or 
737-100/200 SRM 53-10-4, Figure 1, as applicable, before further 
flight, repair in accordance with the procedures specified in paragraph 
(j) of this AD.''
    ATA states that UA indicates that the term ``structural repair 
manual,'' as specified in paragraph (h) of the NPRM, should be replaced 
with ``Service Bulletin 737-53A1261 Part III.''
    We agree that paragraph (h) of this AD should be clarified; there 
are many repairs for this structure specified in the SRM that could be 
installed which may not adequately address the unsafe condition. 
Therefore, we have changed paragraph (h) for clarification, as follows: 
``For airplanes on which a repair has been previously accomplished: If, 
during accomplishment of the corrective actions required by paragraph 
(f) of this AD, it is found that the repair was not done per the Boeing 
737-100/200 SRM 53-10-4, Figure 1, or the Boeing 737-300/400/500 SRM 
53-00-07, Figure

[[Page 38906]]

201, Repair 1, as applicable; before further flight, repair in 
accordance with the procedures specified in paragraph (k) of this AD.''
    SWA requests clarification of paragraphs (h) and (i) of the NPRM. 
SWA states that if an SRM repair is considered a repair option to 
inspection findings per Boeing Alert Service Bulletin 737-53A1261, 
dated January 19, 2006, as indicated in paragraph (h) of the NPRM, then 
paragraph (i) of the NPRM should specify that SRM repairs would be an 
alternative method of compliance (AMOC) and terminating action to the 
inspections specified in that service bulletin.
    We do not agree that paragraph (i) of the NPRM should be changed to 
specify that SRM repairs are an AMOC and terminating action to the 
inspections specified in the service bulletin. The SRM is referenced in 
the service bulletin as an acceptable method for accomplishing certain 
repairs; therefore, it is not necessary to identify the SRM in 
paragraph (i) because the service bulletin (which includes the SRM 
contents) is already identified in that paragraph. We have made no 
change to the AD in this regard.
    Boeing asks that we clarify paragraph (i)(1) of the NPRM to include 
a reference to Appendices A through X to the service bulletin citation, 
for not only the repair, but also the preventive modification. Boeing 
recommends that paragraph (i)(1) be rewritten as follows: 
``Accomplishment of the repair specified in Part 3, or the preventive 
modification specified in Part 4 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1261, including Appendices A 
through X inclusive, dated January 19, 2006.'' Boeing adds that 
paragraph (i)(1) as currently written does not associate the appendices 
to the preventive modification. Appendices A through V of the service 
bulletin are directly applicable to the preventive modification.
    We agree that paragraph (i)(1) of the NPRM (paragraph (j)(1) of 
this AD) should be clarified to add a reference to Appendices A through 
X to the service bulletin citation. This change links the appendices to 
the preventive modification, as well as the repair. We have changed 
paragraph (j)(1) accordingly.
    UA asks that we clarify paragraph (i)(3) of the NPRM. UA notes that 
previously installed SRM repairs do not terminate re-inspections; 
although paragraph (i)(3) may lead an operator to think a previously 
installed SRM repair does terminate those inspections, as they are 
approved by the Manager, Seattle Aircraft Certification Office.
    We understand UA's comment. As we explained previously, for 
clarification we have added a new paragraph (i) to this AD to define 
the action for airplanes on which a repair has been previously 
accomplished. Paragraph (j) of this AD, if accomplished, terminates the 
repetitive inspections required by paragraph (f) of this AD for the 
repaired or modified frames only. We have made no change to the AD in 
this regard.

Request To Clarify Certain Sections of the Preamble of the NPRM

    Boeing requests that certain sections in the preamble of the NPRM 
be clarified for the following reasons:
    1. Boeing states that the first paragraph of the Discussion section 
incorrectly references a Model 737-300 airplane, but the airplane found 
cracked was a Model 737-200 airplane.
    2. Boeing notes that the last sentence specified in the Other 
Related Service Information section specifies that the inspections are 
``recommended.'' Boeing states that the inspections are ``required,'' 
and suggests incorporating this change to the language.
    We acknowledge the commenter's concern. However, the procedures 
specified in the service information are not regulatory; the procedures 
specified in service information can only be required by issuing an AD. 
We agree that the model referenced in the Discussion section was 
incorrect; however, the identified sections of the NPRM do not reappear 
in the final rule. Therefore, we find that no change to the AD is 
necessary in this regard.

Requests To Extend Compliance Times

    SWA, KLM Royal Dutch Airlines (KLM), and UA ask that we extend the 
compliance times for the inspections as follows:
    SWA asks that we consider a different compliance time for airplanes 
that have accomplished Boeing Service Bulletin 737-53A1177, since the 
likelihood of multi-element damage does not exist for airplanes on 
which that service bulletin has been accomplished at stringer 14 left 
or right. SWA recommends aligning the initial grace period and repeat 
intervals at the same frequency as defined in Boeing Service Bulletin 
737-53-1216, section 1.E.; i.e., 9,000 flight cycles after issuance of 
the AD, and repeating the inspections thereafter every 9,000 flight 
cycles. SWA adds that this will align the interior access and 
inspection requirements with the frame inspection requirements in both 
service bulletins. SWA notes that the 9,000-flight-cycle interval would 
also allow each airplane to reach a heavy maintenance opportunity for 
the airplane to be in an appropriate setting for accomplishing the 
required inspections and repairs if required. SWA adds that it had 
several crack findings on airplanes with over 50,000 flight cycles, and 
therefore it cannot consider the Boeing findings an anomaly.
    KLM states that it submitted a service request to Boeing asking 
them to consider a compliance time for Boeing Alert Service Bulletin 
737-53A1261, which is equal to the compliance time given in AD 2006-26-
09, amendment 39-14867 (72 FR 252, January 4, 2007), and Boeing Special 
Attention Service Bulletin 737-53-1216, Revision 1, dated June 8, 2006. 
KLM states that both inspections can then be done simultaneously during 
a C-check, without additional work. KLM adds that Boeing replied to the 
service request in October 2006 stating that no change in compliance 
time was anticipated. KLM notes that the impact of the inspection/
preventive modification required by AD 2006-26-09 is similar to the 
inspection/preventive modification in the NPRM.
    ATA on behalf of its member UA asks that we consider extending the 
repetitive inspection interval from 6,000 to 9,000 flight cycles in 
order to allow airplanes to reach a heavy maintenance opportunity. To 
date, UA states, it has inspected 960 frames per Boeing Alert Service 
Bulletin 737-53A1261 with no crack findings; the airplanes inspected 
ranged from 28,500 to 35,500 total flight cycles. UA suggests that the 
findings on the airplanes cited in the NPRM might be an anomaly rather 
than a trend if other industry findings are similar to UA's.
    We do not agree to extend the compliance times. Although we 
recognize the convenience to the operator if the compliance time is 
aligned with its maintenance inspections, fatigue cracking of the upper 
frame to side frame splice of the fuselage is a significant safety 
issue, and we have determined that the proposed compliance times are 
warranted based on the effectiveness of the inspection procedure and 
the rate of crack growth. In developing appropriate compliance times 
for this AD, we considered those safety issues as well as the 
recommendations of the manufacturer, the availability of necessary 
repair parts, and the practical aspect of accomplishing the required 
inspections within an interval of time that corresponds to the normal 
maintenance schedules of most affected operators. We have made no 
change to the AD in this regard.

[[Page 38907]]

Request for Clarification of Compliance Time

    KLM states that it assumes the new start date of the inspections 
will be the issue date of the AD, instead of the service bulletin issue 
date.
    From this statement we infer that KLM is requesting that we clarify 
the compliance time specified in paragraph (f) of the NPRM. We agree 
that clarification is necessary. We have added a new paragraph (g) to 
the AD to clarify the compliance time. We have re-identified subsequent 
paragraphs accordingly.

Request To Change Cost Estimate

    SWA states that the costs of compliance identified in the NPRM are 
underestimated. SWA states that the inspection, repair of crack 
findings, and terminating action on uncracked frames is close to 1,200 
labor hours at an average labor rate of $80 per work hour. The cost per 
airplane is closer to $96,000 than $3,040. This estimate does not 
include access to the interior of the airplanes, as the airplanes were 
in a heavy maintenance environment.
    We infer that the commenter is asking that we revise the cost 
estimate provided in the NPRM. We do not agree. The cost information 
provided in AD actions describes only the direct costs of the specific 
requirements. Based on the best data available, the manufacturer 
provided the number of work hours to do the required actions for this 
AD. We recognize that, in doing the actions required by an AD, 
operators might 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 might 
vary significantly among operators, are almost impossible to calculate. 
We have made no change to the AD in this regard.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously. We also determined that 
these changes will not increase the economic burden on any operator or 
increase the scope of the AD.

Costs of Compliance

    There are about 1,509 airplanes of the affected design in the 
worldwide fleet. This AD affects about 524 airplanes of U.S. registry. 
The inspections take between 18 and 38 work hours per airplane, 
depending on airplane configuration, at an average labor rate of $80 
per work hour. Based on these figures, the estimated cost of the 
inspections required by this AD for U.S. operators is between $754,560 
and $1,592,960, or $1,440 and $3,040 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

    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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

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 AD:

2008-13-12 Boeing: Amendment 39-15575. Docket No. FAA-2007-0184; 
Directorate Identifier 2007-NM-140-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective August 12, 
2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-100, -200, -200C, -300, 
-400, and -500 series airplanes, certificated in any category; as 
identified in Boeing Alert Service Bulletin 737-53A1261, dated 
January 19, 2006.

Unsafe Condition

    (d) This AD results from a report that the upper frame of the 
fuselage was severed between stringers S-13L and S-14L at station 
747, and the adjacent frame at station 767 had a 1.3-inch-long crack 
at the same stringer location. We are issuing this AD to detect and 
correct fatigue cracking of the upper frame to side frame splice of 
the fuselage, which could result in reduced structural integrity of 
the frame and adjacent lap joint. This reduced structural integrity 
can increase loading in the fuselage skin, which will accelerate 
skin crack growth and result in 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/Corrective Actions

    (f) At the applicable compliance time listed in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1261, 
including Appendices A through X inclusive, dated January 19, 2006; 
except as provided by paragraph (g) of this AD: Do the applicable 
inspections for cracking of the upper frame to side frame splice of 
the fuselage by doing all of the actions, as specified in the 
Accomplishment Instructions of the service bulletin; except as 
provided by paragraphs (h) and (i) of this AD. Do all applicable 
specified and corrective actions before further flight in accordance 
with the service bulletin. Repeat the applicable inspections 
thereafter at intervals not to exceed 6,000 flight cycles until the 
terminating action in paragraph (j) of this AD has been 
accomplished.
    (g) Where Boeing Alert Service Bulletin 737-53A1261, including 
Appendices A

[[Page 38908]]

through X inclusive, dated January 19, 2006, specifies a compliance 
time relative to the date on the service bulletin, this AD requires 
compliance within the specified compliance time after the effective 
date of this AD.
    (h) If any crack is found during any inspection required by this 
AD, and Boeing Alert Service Bulletin 737-53A1261, including 
Appendices A through X inclusive, dated January 19, 2006, specifies 
to contact Boeing for appropriate action: Before further flight, 
repair the crack in accordance with the procedures specified in 
paragraph (k) of this AD.
    (i) For airplanes on which a repair has been previously 
accomplished: If, during accomplishment of the corrective actions 
required by paragraph (f) of this AD, it is found that the repair 
was not done per the Boeing 737-100/200 Structural Repair Manual 
(SRM) 53-10-4, Figure 1, or the Boeing 737-300/400/500 SRM 53-00-07, 
Figure 201, Repair 1, as applicable; before further flight, repair 
in accordance with the procedures specified in paragraph (k) of this 
AD.

Optional Terminating Action

    (j) Accomplishing the actions specified in paragraph (j)(1), 
(j)(2), or (j)(3) of this AD, as applicable, terminates the 
repetitive inspections required by paragraph (f) of this AD for the 
repaired or modified frames only.
    (1) Accomplishment of the repair specified in Part 3, or the 
preventive modification specified in Part 4, of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1261, including 
Appendices A through X inclusive, dated January 19, 2006.
    (2) Accomplishment of the repair or the preventive modification 
specified in Boeing Message M-7200-02-01294, dated August 20, 2002.

Alternative Methods of Compliance (AMOCs)

    (k)(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) 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.

Material Incorporated by Reference

    (l) You must use Boeing Alert Service Bulletin 737-53A1261, 
dated January 19, 2006, to do the actions required by this AD, 
unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    (3) You may review copies of the service information 
incorporated by reference at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on June 12, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-14471 Filed 7-7-08; 8:45 am]
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