[Federal Register Volume 71, Number 89 (Tuesday, May 9, 2006)]
[Proposed Rules]
[Pages 26873-26875]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-7011]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 71, No. 89 / Tuesday, May 9, 2006 / Proposed 
Rules  

[[Page 26873]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24698; Directorate Identifier 2006-NM-026-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-700 and 737-800 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 adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-700 and 737-800 series airplanes. This 
proposed AD would require performing a one-time high frequency eddy 
current inspection for cracking of the backup intercostals located 
above the cutout for the forward airstair door; doing related 
investigative and corrective actions if any crack is found; and doing 
other specified corrective actions if no crack is found. This proposed 
AD results from a report of fatigue cracks discovered during a full-
scale fatigue test conducted by the manufacturer. We are proposing this 
AD to detect and correct such cracking, which could result in more 
extensive fatigue cracking and lead to possible loss of cabin pressure.

DATES: We must receive comments on this proposed AD by June 23, 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 the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: 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.

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 ``FAA-2006-
24698; Directorate Identifier 2006-NM-026-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 DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may 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 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

    This proposed AD results from a report of fatigue cracks discovered 
parallel to a line of fasteners on the two backup intercostals of the 
upper sill web during a full-scale fatigue test conducted by Boeing. We 
also received a report that similar cracks and upper sill web cracks 
were discovered on a Model 737-300 series airplane. This condition, if 
not corrected, could result in more extensive fatigue cracking of the 
backup intercostals and upper sill web and lead to possible loss of 
cabin pressure.

Other Relevant Rulemaking

    As previously mentioned, similar cracking was discovered on a Model 
737-300 series airplane, and it has been determined that the unsafe 
condition also applies to certain Model 737-100, -200, -300, -400, and 
-500 series airplanes. The corrective action for those airplane models 
is similar to that proposed for Model 737-700 and 737-800 series 
airplanes; however, the corrective action will be different due to the 
higher number of flight cycles that have accumulated on these earlier 
airplane models. Because the corrective action will be different, 
Boeing intends to issue a separate service bulletin for Model 737-100, 
-200, -300, -400, and -500 series airplanes. We may consider further 
rulemaking when that service bulletin is issued and approved, rather 
than attempt to include all affected airplane models in this proposed 
AD.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-53-
1236, Revision 1, dated November 10, 2005. The service bulletin 
describes procedures for performing a one-time high frequency eddy 
current (HFEC) inspection for cracking of the backup intercostals of 
the airstair doorway upper sill; doing related investigative and 
corrective actions if any crack is found; and doing other specified

[[Page 26874]]

corrective actions if no crack is found. Related investigative and 
corrective actions include performing an HFEC inspection for cracking 
at certain door stop fastener holes in the upper sill web and 
contacting Boeing for instructions on how to repair any crack 
discovered. Other specified corrective actions include installing 
replacement filler blocks and fasteners. 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 exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between Proposed AD and Service Bulletin.''

Difference Between Proposed AD and Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     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.

Costs of Compliance

    There are about 146 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 54 airplanes of 
U.S. registry. The proposed HFEC inspection would take about 2 work 
hours per airplane, at an average labor rate of $80 per work hour. 
Based on these figures, the estimated cost of the proposed AD for U.S. 
operators is $8,640, or $160 per airplane.

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:

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 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24698; Directorate Identifier 2006-NM-
026-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by June 23, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-700 and 737-800 series 
airplanes, certificated in any category; as identified in Boeing 
Special Attention Service Bulletin 737-53-1236, Revision 1, dated 
November 10, 2005.

Unsafe Condition

    (d) This AD results from a report of fatigue cracks discovered 
during a full-scale fatigue test conducted by the manufacturer. We 
are issuing this AD to detect and correct such cracking, which could 
result in more extensive fatigue cracking and lead to possible loss 
of cabin pressure.

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.

Inspection of Backup Intercostals

    (f) Before the accumulation of 24,000 total flight cycles, or 
within 4,500 flight cycles after the effective date of this AD, 
whichever comes later: Perform a high frequency eddy current (HFEC) 
inspection for cracking of the backup intercostals located above the 
cutout for the forward airstair door, and, before further flight, do 
related investigative actions and applicable corrective actions if 
any crack is found, and other specified corrective actions if no 
crack is found. Related investigative actions, applicable corrective 
actions and other specified corrective actions must be done in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1236, Revision 1, dated November 
10, 2005; except where the service bulletin specifies to contact 
Boeing for repair instructions, repair all cracks using a method 
approved in accordance with the procedures specified in paragraph 
(h) of this AD.

Actions Accomplished Using Original Issue of Service Bulletin

    (g) Actions accomplished before the effective date of this AD in 
accordance with Boeing Service Bulletin 737-53-1236, dated July 11, 
2002, are considered acceptable for compliance with the 
corresponding requirements of this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (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

[[Page 26875]]

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.

    Issued in Renton, Washington, on April 28, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-7011 Filed 5-8-06; 8:45 am]
BILLING CODE 4910-13-P