[Federal Register Volume 70, Number 30 (Tuesday, February 15, 2005)]
[Proposed Rules]
[Pages 7697-7700]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-2836]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20354; Directorate Identifier 2004-NM-166-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500, 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 all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. This proposed AD would require an inspection for chafing of 
certain wire

[[Page 7698]]

bundles located above the center fuel tank, corrective actions if 
necessary, and replacement of wire bundle clamps with new clamps. 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 April 1, 2005.

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.
     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 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-2005-20354; the directorate identifier for this docket is 
2004-NM-166-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-2005-20354; 
Directorate Identifier 2004-NM-166-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.

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 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 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 540 at right buttock line (RBL) and left buttock line (LBL) 
24.50. Although no chafing was found on these wire bundles, if these 
wire bundles chafe, they could arc through the center fuel tank wall, 
which could result in a fuel tank explosion.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-28-1208, dated July 8, 
2004. For all airplane groups, as specified in the service bulletin, 
the service bulletin describes procedures for inspecting for chafed 
wire bundles located below the passenger compartment, above the center 
fuel tank, aft of station 540 to approximately station 663.75, at RBL 
and LBL 24.50, and corrective actions. Depending on the airplane group, 
the corrective actions include repairing any wire damage in accordance 
with chapter 20-

[[Page 7699]]

10-13 of the Boeing Standard Wiring Practices Manual (BSWPM) or an 
``approved equivalent procedure.'' For all airplane groups, the service 
bulletin also includes procedures for replacing the wire bundle clamps 
located immediately aft of station 540. For certain airplane groups, 
the service bulletin includes procedures for adjusting a certain wire 
bundle clamp. 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, except as discussed under 
``Difference Between the Proposed AD and Service Bulletin.''

Difference Between the Proposed AD and Service Bulletin

    For Group 1 airplanes, as specified in Boeing Service Bulletin 737-
28-1208, the service bulletin states that operators may repair wire 
damage according to either chapter 20-10-13 of the BSWPM or an approved 
equivalent procedure. This proposed AD would require operators to 
accomplish the repair of any wire damage according to the procedures in 
the BSWPM. An approved equivalent procedure for the repair of wire 
damage may be used only if approved as an alternative method of 
compliance under the provisions of paragraph (h) of this proposed AD.
    Where the service bulletin states that a specific chapter of the 
Boeing 737 Airplane Maintenance Manual or an approved equivalent 
procedure may be used for removing and re-installing passenger cabin 
furnishings, and removing and returning power to the airplane, an 
approved equivalent procedure may be used.

Clarification of Inspection Terminology

    In this proposed AD, the ``inspection'' specified in the Boeing 
service bulletin is referred to as a ``detailed inspection.'' We have 
included the definition for a detailed inspection in a note in the 
proposed AD.

Costs of Compliance

    This proposed AD would affect about 2,871 airplanes worldwide. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                                     Estimated Costs
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                                                                                                                          Number of U.S.-
                         Action                             Work hours     Average labor       Parts         Cost per       registered      Fleet cost
                                                                           rate per hour                     airplane        airplanes
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Inspection..............................................               2             $65            None            $130            1042        $135,460
Replacement of wire bundle clamps.......................               2              65            $190             320            1042         333,440
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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-2005-20354; Directorate Identifier 2004-NM-
166-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by April 1, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes, certificated in any category.

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.

[[Page 7700]]

Inspection of Wire Bundles and Corrective Actions

    (f) Within 60 months after the effective date of this AD: 
Perform a detailed inspection for chafing of the wire bundles 
located below the passenger compartment, above the center fuel tank, 
aft of station 540 to approximately station 663.75, right buttock 
line and left buttock line 24.50, and any applicable corrective 
actions, by accomplishing all of the applicable actions specified in 
the Accomplishment Instructions of Boeing Service Bulletin 737-28-
1208, dated July 8, 2004. Any corrective actions must be done before 
further flight. Where the service bulletin states that repair of 
wire damage may be done in accordance with an ``approved equivalent 
procedure,'' the repair must be accomplished according to the 
chapter of the Boeing Standard Wiring Practices Manual specified in 
the service bulletin. Approved equivalent procedures may be used for 
removing and re-installing passenger cabin furnishings, and removing 
and returning power to the airplane.

    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.''

Adjustment/Replacement of Wire Bundle Clamps

    (g) After performing the actions required by paragraph (f) of 
this AD: Before further flight, adjust and replace, as applicable, 
the wire bundle clamps located aft of station 540, by accomplishing 
all of the applicable actions specified in the Accomplishment 
Instructions of Boeing Service Bulletin 737-28-1208, dated July 8, 
2004.

Alternative Methods of Compliance

    (h) 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 February 6, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-2836 Filed 2-14-05; 8:45 am]
BILLING CODE 4910-13-P