[Federal Register Volume 69, Number 172 (Tuesday, September 7, 2004)]
[Proposed Rules]
[Pages 54053-54055]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-20212]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19022; Directorate Identifier 2004-NM-122-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-600, -700, -700C, -800, and -900 series 
airplanes. This proposed AD would require repetitive detailed, low 
frequency eddy current, and high frequency eddy current inspections of 
the webs of the aft pressure bulkhead at body station 1016 for cracks, 
and corrective action if necessary. This proposed AD is prompted by a 
report of cracks found, during fatigue testing, at several of the 
fastener rows in the web lap splices at the dome apex of the aft 
pressure bulkhead. We are proposing this AD to detect and correct 
fatigue cracks in the webs of the aft pressure bulkhead, which could 
result in rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by October 22, 
2004.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov

[[Page 54054]]

and follow the instructions for sending your comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW, Nassif Building, room PL-401, 
Washington, DC 20590.
     By fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street SW, Washington, DC, between 9 a.m. 
and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    You can examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street SW., room PL-401, on 
the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Technical information: 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.
    Plain language information: Marcia Walters, [email protected].

SUPPLEMENTARY INFORMATION: 

Docket Management System (DMS)

    The FAA has implemented new procedures for maintaining AD dockets 
electronically. As of May 17, 2004, new AD actions are posted on DMS 
and assigned a docket number. We track each action and assign a 
corresponding directorate identifier. The DMS AD docket number is in 
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane 
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier 
(``Old Docket Number'') as a cross-reference for searching purposes.

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-19022; 
Directorate Identifier 2004-NM-122-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that website, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit http://dms.dot.gov.
    We are reviewing the writing style we currently use in regulatory 
documents. We are interested in your comments on whether the style of 
this document is clear, and your suggestions to improve the clarity of 
our communications that affect you. You can get more information about 
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

    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 DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the DMS receives them.

Discussion

    We have received a report that, during fatigue testing, the 
manufacturer found cracks at several of the fastener rows in the web 
lap splices at the dome apex of the aft pressure bulkhead on a Boeing 
737-800 series airplane. Cracks were found in three of the seven webs. 
The single rivet located where each of the webs transition up 0.032 
inches over the adjacent web causes pull down loading, which leads to 
cracks at the rivet holes of the web lap splices. This condition, if 
not detected and corrected, could result in rapid decompression of the 
airplane.
    The web lap splices on certain Model 737-600, -700, -700C, and -900 
series airplanes are identical to those on the affected Model 737-800 
series airplanes. Therefore, all of these models may be subject to the 
same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-53-1251, dated June 3, 
2004. The service bulletin describes procedures for doing repetitive 
detailed inspections, low frequency eddy current (LFEC) inspections, 
and high frequency eddy current (HFEC) inspections of the webs of the 
aft pressure bulkhead at body station 1016 from the aft side at the 
dome apex for cracks; and contacting the manufacturer for repair 
instructions if cracks are found. We have determined that accomplishing 
the actions specified in the service bulletin will adequately address 
the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. Therefore, we are proposing this AD, which 
would require doing repetitive detailed inspections, LFEC inspections, 
and HFEC inspections of the webs of the aft pressure bulkhead at body 
station 1016 from the aft side at the dome apex for cracks, and 
corrective action if necessary. The corrective action includes 
repairing any crack found during any inspection in accordance with a 
method approved by the FAA; or per data meeting the type certification 
basis of the airplane approved by a Boeing Company Designated 
Engineering Representative (DER) who has been authorized by the FAA to 
make those findings. The proposed AD would require you to use the 
service information described previously to perform these actions, 
except as discussed under ``Differences Between the Proposed AD and the 
Service Bulletin.''

Differences Between the Proposed AD and the Service Bulletin

    Operators should note that, although the service bulletin does not 
list a grace period in the compliance times, this proposal adds a grace 
period to the compliance times. The FAA finds that such a grace period 
will keep airplanes from being grounded unnecessarily.
    Operators should also note that although the service bulletin 
specifies that operators may contact the manufacturer for disposition 
of certain repair conditions, this proposed AD would require operators 
to repair those conditions per a method approved by the FAA; or per 
data meeting the type certification basis of the airplane approved by a 
Boeing Company DER

[[Page 54055]]

who has been authorized by the FAA to make those findings.

Costs of Compliance

    This proposed AD would affect about 457 airplanes of U.S. registry 
and 1,166 airplanes worldwide. The proposed actions would take about 8 
work hours per airplane, at an average labor rate of $65 per work hour. 
Based on these figures, the estimated cost of the proposed AD for U.S. 
operators is $237,640, or $520 per airplane, per inspection cycle.

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

Boeing: Docket No. FAA-2004-19022; Directorate Identifier 2004-NM-
122-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by October 22, 2004.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, -800, 
and -900 series airplanes, certificated in any category; as listed 
in Boeing Service Bulletin 737-53-1251, dated June 3, 2004.

Unsafe Condition

    (d) This AD was prompted by a report of cracks found, during 
fatigue testing, at several of the fastener rows in the web lap 
splices at the dome apex of the aft pressure bulkhead. We are 
issuing this AD to detect and correct fatigue cracks in the webs of 
the aft pressure bulkhead, which could result in 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 and Repetitive Inspections

    (f) Prior to accumulating 26,000 total flight cycles or within 
4,000 flight cycles after the effective date of this AD, whichever 
occurs later: Do a detailed inspection, low frequency eddy current 
inspection, and high frequency eddy current inspection of the webs 
of the aft pressure bulkhead at body station 1016 for cracks, in 
accordance with Boeing Service Bulletin 737-53-1251, dated June 3, 
2004. Repeat the inspections thereafter at intervals not to exceed 
4,000 flight cycles.


    Note 1:  For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Corrective Action

    (g) If any crack is found during any inspection required by 
paragraph (f) of this AD: Before further flight, 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 by a Boeing Company Designated Engineering 
Representative (DER) who has been authorized by the Manager, Seattle 
ACO, to make such findings. For a repair method to be approved, the 
approval must specifically reference this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle ACO, FAA, 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 any repair required by this AD, if it is approved by a 
Boeing Company DER who has been authorized by the Manager, Seattle 
ACO, to make those findings. For a repair method to be approved, the 
approval must specifically refer to this AD.

    Issued in Renton, Washington, on August 27, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-20212 Filed 9-3-04; 8:45 am]
BILLING CODE 4910-13-P