Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes, 38636-38637 [05-13141]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 127 (Tuesday, July 5, 2005)]
[Proposed Rules]
[Pages 38636-38637]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-13141]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21714; Directorate Identifier 2005-NM-065-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 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 737-600, -700, -700C, -800, and -900 series 
airplanes. This proposed AD would require modification of certain wire 
bundles located above the center fuel tank. This proposed AD is 
prompted by the results of fuel system reviews conducted by the 
manufacturer. We are proposing this AD to prevent chafed wire bundles 
near the center fuel tank, which could cause electrical arcing through 
the tank wall and ignition of fuel vapor in the fuel tank, and result 
in a fuel tank explosion.

DATES: We must receive comments on this proposed AD by August 19, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to https://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to https://
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.
     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 
https://dms.dot.gov, or in person 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. This docket 
number is FAA-2005-21714; the directorate identifier for this docket is 
2005-NM-065-AD.

FOR FURTHER INFORMATION CONTACT: Binh Tran, Aerospace Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6485; 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 under ADDRESSES. Include ``Docket No. FAA-2005-21714; 
Directorate Identifier 2005-NM-065-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 https://
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 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 https://dms.dot.gov.

Examining the Docket

    You can examine the AD docket on the Internet at https://
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 
(DMS) receives them.

Discussion

    We have examined the underlying safety issues involved in recent 
fuel tank explosions on several large transport airplanes, including 
the adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(67 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: Single failures, single failures in 
combination with another latent condition(s), and in-service failure 
experience. For all four criteria, the evaluations included 
consideration of previous actions taken that may mitigate the need for 
further action.
    Based on this process, we have determined that the actions 
identified in this proposed AD are necessary to

[[Page 38637]]

reduce the potential of ignition sources near fuel tanks, which, in 
combination with flammable fuel vapors, could result in fuel tank 
explosions and consequent loss of the airplane.
    A Boeing and FAA team inspected several 737 airplanes as part of 
the SFAR 88 system safety analysis. The team identified wire bundles in 
close proximity of the center fuel tank. The wire bundles were located 
below the passenger compartment, above the center fuel tank, aft of 
station (STA) 540 at right buttock line (RBL) and left buttock line 
(LBL) 24.82. Although no chafing was found on these wire bundles, if 
these wire bundles chafe, they could arc through the center fuel tank 
wall, ignite fuel vapor in the fuel tank, and result in a fuel tank 
explosion.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-28-1209, dated 
February 17, 2005. The service bulletin describes procedures for 
modifying the wire bundles located below the passenger compartment, 
above the center fuel tank, aft of station (STA) 540 through STA 601 
inclusive, at RBL and LBL 24.82. The modification includes, among other 
actions, replacing the nutplate standoffs with support brackets. 
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. Therefore, we are proposing this AD, which 
would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 1,636 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 650 airplanes of 
U.S. registry. The proposed modification would take about 4 work hours 
per airplane, at an average labor rate of $65 per work hour. Required 
parts would cost about $1,446 per airplane. Based on these figures, the 
estimated cost of the proposed AD for U.S. operators is $1,108,900, or 
$1,706 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. 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-2005-21714; Directorate Identifier 2005-NM-
065-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by August 19, 2005.

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 
identified in Boeing Service Bulletin 737-28-1209, dated February 
17, 2005.

Unsafe Condition

    (d) This AD was prompted by the results of fuel system reviews 
conducted by the manufacturer. We are issuing this AD to prevent 
chafed wire bundles near the center fuel tank, which could cause 
electrical arcing through the tank wall and ignition of fuel vapor 
in the fuel tank, and result in a fuel tank explosion.

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.

Modification

    (f) Within 60 months after the effective date of this AD: Modify 
the wire bundles located below the passenger compartment, above the 
center fuel tank, aft of station (STA) 540 through STA 601 
inclusive, at right buttock line and left buttock line 24.82 in 
accordance with Boeing Service Bulletin 737-28-1209, dated February 
17, 2005.

Alternative Methods of Compliance (AMOCs)

    (g) The Manager, Seattle Aircraft Certification Office, FAA, has 
the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

    Issued in Renton, Washington, on June 24, 2005.
Michael J. Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-13141 Filed 7-1-05; 8:45 am]
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