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

[Federal Register Volume 73, Number 191 (Wednesday, October 1, 2008)]
[Rules and Regulations]
[Pages 56958-56960]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-22755]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0947; Directorate Identifier 2008-NM-154-AD; 
Amendment 39-15670; AD 2008-19-03]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Boeing Model 737-300, -400, and -500 series airplanes. This AD requires 
repetitive external detailed inspections or non-destructive inspections 
to detect cracks in the fuselage skin along the chem-mill steps at 
stringers S-1 and S-2R, between station (STA) 400 and STA 460, and 
repair if necessary. This AD results from reports of cracks in the 
fuselage skin common to stringer S-1 and between STA 400 and STA 460. 
We are issuing this AD to detect and correct fatigue cracking of the 
fuselage skin panels at the chem-mill steps, which could result in 
sudden fracture and failure of the fuselage skin panels, and consequent 
rapid decompression of the airplane.

DATES: This AD is effective October 16, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 16, 
2008.
    We must receive comments on this AD by December 1, 2008.

ADDRESSES: You may send comments by any of the following methods:
    <bullet> Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
    <bullet> Fax: 202-493-2251.
    <bullet> 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.
    <bullet> 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.

[[Page 56959]]

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 street address for 
the Docket Office (telephone 800-647-5527) is in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

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 received three reports of cracks in the fuselage skin common to 
stringer S-1 and between station (STA) 400 and STA 460. In all three 
cases, there were cracks in adjacent 10-inch tear strap bays. In one 
case, there were cracks in four adjacent 10-inch tear strap bays. The 
cracks measured between 4.0 and 10.5 inches long. The airplanes had 
accumulated between 42,038 and 57,523 total flight cycles. Analysis 
indicates that the cracks were caused by fatigue due to high tension 
stresses and local bending at the edge of the chem-mill pockets of the 
bonded fuselage skin. Airplanes with 20-inch tear strap bays are also 
susceptible to cracks at this location. Fatigue cracking of the 
fuselage skin panels at the chem-mill steps, if not detected and 
corrected, could result in sudden fracture and failure of the fuselage 
skin panels, and consequent rapid decompression of the airplane.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1293, dated August 
13, 2008. The service bulletin describes procedures for repetitive 
external detailed inspections or non-destructive inspections (NDI) to 
detect cracks in the fuselage skin along the chem-mill steps at 
stringers S-1 and S-2R between STA 400 and STA 460, and contacting 
Boeing for repair instructions. The NDI inspections that can be used 
are medium frequency eddy current, magneto optical imaging, or c-scan. 
For the initial inspection, the service bulletin specifies a compliance 
time of before 35,000 total flight cycles, or within 500 flight cycles 
after the date on the service bulletin, whichever occurs later. For the 
repetitive inspections, the service bulletin specifies repeat intervals 
ranging between 1,200 and 4,500 flight cycles, depending on the 
airplane configuration and the type of inspection previously done.

FAA's Determination and Requirements of This AD

    We are issuing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the(se) same type 
design(s). This AD requires accomplishing the actions specified in the 
service information described previously, except as discussed under 
``Difference Between the AD and the Service Information.''

Difference Between the AD and the Service Information

    Boeing Alert Service Bulletin 737-53A1293, dated August 13, 2008, 
specifies contacting the manufacturer for instructions on how to repair 
a certain condition, but this AD requires repairing that condition in 
one of the following ways:
    <bullet> Using a method that we approve; or
    <bullet> 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.

Interim Action

    We consider this AD interim action. If final action is later 
identified, we might consider further rulemaking then.

FAA's Justification and Determination of the Effective Date

    We are issuing this AD to detect and correct fatigue cracking of 
the fuselage skin panels at the chem-mill steps, which could result in 
sudden fracture and failure of the fuselage skin panels, and consequent 
rapid decompression of the airplane. Because of our requirement to 
promote safe flight of civil aircraft and thus, the critical need to 
assure the structural integrity of the fuselage and the short 
compliance time involved with this action, this AD must be issued 
immediately.
    Because an unsafe condition exists that requires the immediate 
adoption of this AD, we find that notice and opportunity for prior 
public comment hereon are impracticable and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety, and we did not provide you with notice and an opportunity to 
provide your comments before it becomes effective. However, we invite 
you to send any written data, views, or arguments about this AD. Send 
your comments to an address listed under the ADDRESSES section. Include 
``Docket No. FAA-2008-0947; Directorate Identifier 2008-NM-154-AD'' at 
the beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of this 
AD. We will consider all comments received by the closing date and may 
amend this 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 AD.

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,

[[Page 56960]]

    (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:

2008-19-03 Boeing: Amendment 39-15670. Docket No. FAA-2008-0947; 
Directorate Identifier 2008-NM-154-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective October 16, 
2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category; as identified in 
Boeing Alert Service Bulletin 737-53A1293, dated August 13, 2008.

Unsafe Condition

    (d) This AD results from reports of cracks in the fuselage skin 
common to stringer S-1 and between station (STA) 400 and STA 460. We 
are issuing this AD to detect and correct fatigue cracking of the 
fuselage skin panels at the chem-mill steps, which could result in 
sudden fracture and failure of the fuselage skin panels, and 
consequent rapid decompression of the airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Repetitive Inspections

    (f) At the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1293, dated 
August 13, 2008 (hereafter ``the service bulletin''); except where 
the service bulletin specifies a compliance time after the date on 
the service bulletin, this AD requires compliance within the 
specified compliance time after the effective date of this AD: Do 
repetitive external detailed inspections or non-destructive 
inspections (NDI) to detect cracks in the fuselage skin along the 
chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 
460, by accomplishing the applicable inspections specified in the 
Accomplishment Instructions of the service bulletin.

Repair

    (g) If any crack is found during any inspection required by 
paragraph (f) of this AD, before further flight, repair the cracked 
fuselage skin using a method approved in accordance with the 
procedures specified in paragraph (h) of this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-
120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 
98057-3356; telephone (425) 917-6447; 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

    (i) You must use Boeing Alert Service Bulletin 737-53A1293, 
dated August 13, 2008, 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 September 11, 2008.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-22755 Filed 9-30-08; 8:45 am]
BILLING CODE 4910-13-P

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