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

[Federal Register Volume 73, Number 161 (Tuesday, August 19, 2008)]
[Rules and Regulations]
[Pages 48288-48290]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-18812]


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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; 
Amendment 39-15641; AD 2008-17-03]
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 repetitive inspections to detect cracking 
of the body station 303.9 frame, and corrective action if necessary. 
This AD also provides for optional terminating action for the 
repetitive inspections. 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.

DATES: This AD is effective September 23, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of September 23, 
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: 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: 

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 September 
13, 2007 (72 FR 52314). That NPRM proposed to require repetitive 
inspections to detect cracking of the body station 303.9 frame, and 
corrective action if necessary. That NPRM also proposed optional 
terminating action for the repetitive inspections.

Comments

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

Support for the NPRM

    Boeing concurs with the NPRM.

Request To Delay Final Rule

    The Air Transport Association (ATA), on behalf of its member United 
Airlines, requests that we delay issuing the final rule until kits (to 
repair cracks or to terminate the repetitive inspections) are readily 
available from Boeing. Only Boeing kits are specified; Boeing kit 
65C37763-8 is under parts management control by Boeing.
    We disagree with the request to delay issuing the final rule. To 
delay this action would be inappropriate, since we have determined that 
an unsafe condition exists, and that inspections must be conducted in a 
timely manner to ensure continued safety. Boeing is aware of the 
pending AD. We have been advised that kits are currently available from 
Boeing Spares, and that Boeing has already made forecasts to ensure 
continued kit availability. Operators that order out-of-stock kits from 
Boeing can request permission from Boeing Spares to manufacture the 
kits. We have been advised that Boeing Spares will provide the drawings 
and specifications required to make kits. The kits related to this AD 
are made up of simple parts that should be easy for operators to 
fabricate. We have not changed the final rule regarding this issue.

Request To Allow Existing Repairs as Terminating Action

    Continental requests that we revise the NPRM to allow existing FAA-
approved repairs (in the inspection area specified in the NPRM) as 
terminating action for the proposed repetitive inspections. The 
commenter notes that the service bulletin has no provisions for 
inspecting existing FAA-approved repairs.
    While certain previously installed repairs might be acceptable as a 
terminating action for the AD inspections, we cannot classify all 
previously installed repairs--even ones approved by the FAA--as 
terminating action unless the repair is properly evaluated in light of 
the requirements of this AD. Paragraph (j) of the final rule provides 
operators the opportunity to request approval of specific repair 
configurations as terminating action. Such a request should include 
data/rationale to show that the repair configuration provides an 
acceptable level of safety without continued inspections. We have not 
changed the final rule regarding this issue.

Request To Extend Grace Period

    Continental Airlines requests that we revise the NPRM to extend the 
grace period for the initial inspection (for airplanes that have 
exceeded the specified flight-cycle threshold). The commenter requests 
an extension from 2,250 flight cycles to 4,500 flight cycles to 
coincide with a scheduled heavy maintenance check. The commenter 
asserts that the proposed grace period would not give operators 
adequate time to comply with the AD without added financial and 
logistical burden on the airlines. The commenter refers to AD 2005-20-
03, amendment 39-14296 (70 FR 56361, September 27, 2005). That AD also 
applies to 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. The commenter states that 
the inspection area is the same for AD 2005-20-03 and the subject NPRM. 
The grace period for that AD is 4,500 flight cycles, so extending the 
grace period in the NPRM to 4,500 flight cycles will provide an 
acceptable safety level in this AD.
    We agree with the commenter's request and rationale. We have 
revised paragraph (h) in this final rule accordingly. We have 
coordinated this change with Boeing.

[[Page 48289]]

Request To Relax Dimensional Tolerances

    Continental requests that the dimensional requirements be specified 
to a maximum of two decimal places with a tolerance of <plus-minus> 
0.03 inch. Figure 11, detail A, of Boeing Alert Service Bulletin 737-
53A1188, Revision 2, dated May 9, 2007, specifies enlarging the slotted 
hole to dimensions of three decimal places. (Boeing Alert Service 
Bulletin 737-53A1197, dated August 25, 2006, contains similar 
specifications.) The commenter asserts that a tight (three-decimal-
place) tolerance is virtually impossible to attain with this particular 
modification.
    We agree that the noted dimension in the service bulletin is shown 
to three decimal places. But we disagree that the actual ``build to'' 
or ``measure to'' dimensions must be controlled to three decimal 
places. According to paragraph 3.A. of the Accomplishment Instructions 
of the service bulletin, the tolerance for linear dimensions is <plus-
minus> 0.03 inch. Given the two-decimal-place accuracy of this 
tolerance, the corresponding final dimension will require only two-
decimal-place accuracy. So, for example, for a specified dimension of 
1.29900 <plus-minus> 0.03, the final ``build to'' and ``measure to'' 
dimensions, when appropriately rounded to the 2-decimal-place tolerance 
accuracy, are 1.27-1.33. We have not changed the final rule regarding 
this issue.

Clarification of Required Service Information

    We have revised the final rule to clarify that Revision 2 of Boeing 
Alert Service Bulletin 737-53A1188 must be used for the requirements of 
paragraph (f) of this AD.

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 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 AD.

                                                                     Estimated Costs
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                                                                                                                   Number of U.S.-
             Action                    Work hours        Average labor         Parts          Cost per airplane       registered          Fleet cost
                                                         rate per hour                                                airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
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 $5,349,944.
 done.
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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

    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:

2008-17-03 Boeing: Amendment 39-15641. Docket No. FAA-2007-29174; 
Directorate Identifier 2007-NM-125-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective September 23, 
2008.

Affected ADs

    (b) None.

Applicability

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

[[Page 48290]]



                         Table 1--Applicability
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                                          As identified in Boeing Alert
             Boeing model--                     Service Bulletin--
------------------------------------------------------------------------
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.
------------------------------------------------------------------------

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 Revision 2 of the service bulletin. 
Do the inspections at the applicable time specified in paragraph 
1.E. of Revision 2 of the service bulletin, except as provided by 
paragraph (h) of this AD. Do all applicable corrective actions 
before further flight in accordance with Revision 2 of 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 
Revision 2 of 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 paragraph 3.B., Part II, 
step 3, or Part III, step 3, of Revision 2 of the service bulletin.

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. For the initial 
inspection, the grace period for airplanes that have exceeded the 
specified threshold is extended to 4,500 flight cycles 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, FAA, 
ATTN: Howard Hall, Aerospace Engineer, Airframe Branch, ANM-120S; 
telephone (425) 917-6430; fax (425) 917-6590; 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.

Material Incorporated by Reference

    (k) You must use Boeing Alert Service Bulletin 737-53A1188, 
Revision 2, dated May 9, 2007; or Boeing Alert Service Bulletin 737-
53A1197, dated August 25, 2006; as applicable; 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 August 6, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-18812 Filed 8-18-08; 8:45 am]
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