[Federal Register Volume 71, Number 69 (Tuesday, April 11, 2006)]
[Proposed Rules]
[Pages 18251-18253]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3442]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24369; Directorate Identifier 2006-NM-001-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Boeing Model 737-600, -700, -
700C, and -800 series airplanes. The existing AD currently requires 
replacing the point ``D'' splice fitting between windows number 1 and 2 
with a new splice fitting; performing an eddy current inspection for 
cracking of the holes in the structure common to the new splice 
fitting, including doing any related investigative actions; and 
performing corrective actions if necessary. This proposed AD would add 
repetitive inspections for cracking of the skin just below each splice 
fitting, and related corrective actions if necessary. This proposed AD 
results from full-scale fuselage fatigue testing on the splice fitting 
that failed prior to the design objective on Boeing Model 737-800 
series airplanes, and a report of a cracked splice fitting on an 
operational airplane. We are proposing this AD to prevent cracking of 
the existing fitting, which may result in cracking through the skin and 
consequent decompression of the flight cabin.

DATES: We must receive comments on this proposed AD by May 26, 2006.

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 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.
     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.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Sue Lucier, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6438; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``Docket No. 
FAA-2006-24369; Directorate Identifier 2006-NM-001-AD'' at the 
beginning 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 received 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 Web site, 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 may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or visit 
http://dms.dot.gov.

Examining the Docket

    You may 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

[[Page 18252]]

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 Docket Management System receives them.

Discussion

    On November 25, 2005, we issued AD 2005-25-03, amendment 39-14396 
(70 FR 72595, December 6, 2005), for certain Boeing Model 737-600, -
700, -700C, and -800 series airplanes. That AD requires replacing the 
point ``D'' splice fitting between windows number 1 and 2 with a new 
splice fitting; performing an eddy current inspection for cracking of 
the holes in the structure common to the new splice fitting, including 
doing any related investigative actions; and performing corrective 
actions if necessary. That AD resulted from full-scale fuselage fatigue 
testing on the splice fitting that failed prior to the design objective 
on Boeing Model 737-800 series airplanes, and a report of a cracked 
splice fitting on an operational airplane. We issued that AD to prevent 
cracking of the existing fitting, which may result in cracking through 
the skin and consequent decompression of the flight cabin.

Since the Existing AD Was Issued

    In the preamble to AD 2005-25-03, we indicated that the actions 
required by that AD were considered ``interim action'' and that further 
rulemaking action was being considered. We have determined that further 
rulemaking action is indeed necessary, and this proposed AD follows 
from that determination.

Relevant Service Information

    We have previously reviewed Boeing Alert Service Bulletin (ASB) 
737-53A1222, Revision 2, dated October 20, 2005, the appropriate 
service information referenced in AD 2005-25-03. The ASB describes 
procedures for replacing the splice fitting between windows number 1 
and 2, at point ``D'' on the windowsill with a new splice fitting, and 
performing related investigative actions. Those investigative actions 
include performing an open hole eddy current inspection for cracking of 
the fastener holes, and a special detailed inspection for cracking of 
12 fasteners in the adjacent structure. The ASB also describes 
procedures for repetitive detailed inspections of the skin near the six 
skin fasteners below the splice fitting. The ASB specifies that if 
cracking is detected, to contact Boeing for further instructions. 
Accomplishing the actions specified in the service information is 
intended to 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 develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2005-25-03 and retain the requirements of the 
existing AD. This proposed AD would also require accomplishing 
repetitive external detailed inspections of the skin near the six skin 
fasteners below the splice fitting, specified in the ASB described 
previously.

Differences Between the AD and the ASB

    Where the ASB specifies contacting Boeing if any cracking is 
detected, this AD would require that repair of any cracking be 
accomplished before further flight, in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office (ACO).

Costs of Compliance

    There are about 563 airplanes of the affected design in the 
worldwide fleet. We estimate that about 243 airplanes are on the U.S. 
Register, and that the average labor rate is $80 per hour. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                 Estimated Costs
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                                                                                     Cost per
                     Action                         Work hours         Parts         airplane       Fleet cost
----------------------------------------------------------------------------------------------------------------
Replacing splice fittings with new fittings                   36         $15,445         $18,325      $4,452,975
 (required by AD 2005-25-03)....................
External detailed inspection (new proposed                     1               0              80        *19,440
 action)........................................
----------------------------------------------------------------------------------------------------------------
* 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 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 and placed it in the AD docket. 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:

[[Page 18253]]

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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-14396 (70 FR 72595, December 6, 2005) and adding 
the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24369; Directorate Identifier 2006-NM-
001-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 26, 
2006.

Affected ADs

    (b) This AD supersedes AD 2005-25-03.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, and -
800 series airplanes, certificated in any category; as identified in 
Boeing Alert Service Bulletin (ASB) 737-53A1222, Revision 2, dated 
October 20, 2005.

Unsafe Condition

    (d) This AD results from full-scale fuselage fatigue testing on 
a splice fitting that failed prior to the design objective on Boeing 
Model 737-800 series airplanes, and a report of a cracked splice 
fitting on an operational airplane. We are issuing this AD to 
prevent cracking of the existing fitting, which may result in 
cracking through the skin and consequent decompression of the flight 
cabin.

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.

Restatement of Certain Requirements of AD 2005-25-03

Replacing the Splice Fittings

    (f) Replace the splice fittings with new splice fittings in 
accordance with the Accomplishment Instructions of Boeing ASB 737-
53A1222, Revision 2, dated October 20, 2005, at the times specified 
in paragraph (f)(1) or (f)(2) of this AD, as applicable. Before 
further flight, do any related investigative actions by 
accomplishing all the applicable actions specified in the 
Accomplishment Instructions.
    (1) For airplanes that have accumulated fewer than 13,500 total 
flight cycles as December 21, 2005 (the effective date of AD 2005-
25-03): Replace prior to the accumulation of 13,500 total flight 
cycles, or within 1,000 flight cycles after December 21, 2005, 
whichever occurs later.
    (2) For airplanes that have accumulated 13,500 or more total 
flight cycles as of December 21, 2005: Replace at the later of the 
times specified in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD.
    (i) Prior to the accumulation of 18,000 total flight cycles, or 
within 1,000 flight cycles after December 21, 2005, whichever occurs 
first.
    (ii) Within 90 days after December 21, 2005.

New Requirements of This AD

Repetitive Inspections

    (g) Within 24,000 flight cycles after accomplishing the actions 
specified in paragraph (f) of this AD, perform an external detailed 
inspection of the skin just below each splice fitting, in accordance 
with the Accomplishment Instructions of Boeing ASB 737-53A1222, 
Revision 2, dated October 20, 2005. Thereafter, repeat the external 
detailed inspections at intervals not to exceed 24,000 flight 
cycles.

Corrective Actions

    (h) If any cracking is found during any inspection required by 
this AD, prior to further flight, repair in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA, or with a method approved in accordance with the 
procedures specified in paragraph (j) of this AD.

Acceptable Method of Compliance

    (i) Replacing the splice fitting and any related investigative 
actions before December 21, 2005 (the effective date of AD 2005-25-
03), in accordance with Boeing Service Bulletin 737-53-1222, dated 
June 6, 2002; or Boeing ASB 737-53A1222, Revision 1, dated January 
30, 2003, is acceptable for compliance with the requirements of 
paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(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) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.
    (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.
    (4) AMOCs approved previously in accordance with AD 2005-25-03, 
amendment 39-14396, are approved as AMOCs for the corresponding 
provisions of paragraphs (f) and (h) of this AD.

    Issued in Renton, Washington, on March 31, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3442 Filed 4-10-06; 8:45 am]
BILLING CODE 4910-13-P