[Federal Register Volume 69, Number 241 (Thursday, December 16, 2004)]
[Proposed Rules]
[Pages 75280-75282]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-27519]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19891; Directorate Identifier 2004-NM-136-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes Modified in Accordance With Supplemental Type 
Certificate (STC) ST00127BO

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 Boeing Model 737-300, -400, and -500 series airplanes modified in 
accordance with STC ST00127BO. This proposed AD would require 
installation of bonding straps to the safe side harnesses of the 
digital transient suppression device of the fuel quantity indicating 
system. This proposed AD is prompted by the results of fuel system 
reviews conducted by the STC holder. We are proposing this AD to 
prevent unsafe levels of current or energy from entering the fuel tank, 
due to hot short faults or threat conditions associated with the safe 
side harness assembly, which could result in a fire or explosion of the 
fuel tank.

DATES: We must receive comments on this proposed AD by January 31, 
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 
Goodrich Fuel & Utility Systems, Goodrich Corporation, 100 Panton Road, 
Vergennes, Vermont 05491.
    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-2004-19891; the directorate identifier for this 
docket is 2004-NM-136-AD.

FOR FURTHER INFORMATION CONTACT:
    Technical information: Richard Spencer, Aerospace Engineer, Boston 
Aircraft Certification Office, ANE-150, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, Massachusetts 
01803; telephone (781) 238-7184; fax (781) 238-7170.
    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 relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-19891; 
Directorate Identifier 2004-NM-136-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 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 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

    The FAA has 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

[[Page 75281]]

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.
    We have determined that the actions identified in this AD are 
necessary to reduce the potential of ignition sources inside fuel 
tanks, which, in combination with flammable fuel vapors, could result 
in fuel tank explosions and consequent loss of the airplane.
    As a result of fuel system reviews associated with SFAR 88, the STC 
holder determined that the existing design of the safe side harness for 
the digital transient suppression device (DTSD) does not incorporate a 
method of positively bonding the harness shields to the airframe on 
certain Boeing transport category airplanes that have been modified in 
accordance with STC ST00127BO. The DTSD is designed to limit current 
and energy present during external threat (lightning/electromagnetic 
interference (EMI)) conditions from being introduced to the fuel 
quantity indicating system (FQIS) wiring. Bonding of the shielded safe 
side wire harnesses that extend from the DTSD to the fuel tank entry is 
essential to ensure that any induced threats or hot short faults are 
limited to safe levels. Unsafe levels of current or energy entering the 
fuel tank, due to hot short faults or threat conditions associated with 
the safe side harness assembly, if not corrected, could result in a 
fire or explosion of the fuel tank.

Relevant Service Information

    We have reviewed Goodrich Service Bulletin 737-300766-28-2, 
Revision 2, dated July 28, 2004. The service bulletin describes 
procedures for:
    1. Installing bonding straps on each safe side harness.
    2. Modifying each safe side harness connector backshell at the tank 
penetrations and at the DTSDs.
    3. Replacing only the backshell for all circular tank and center 
tank penetrations and DTSD connections that use a short 90 degree 
connector backshell.
    4. Replacing the whole backshell for all rectangular wing tank 
penetrations that use a long 90 degree connector backshell.
    5. Installing ground bracket(s) at the wing tank penetration(s).
    6. Installing a ground bracket at the center tank penetration.
    7. Installing a ground bracket at wing station DTSD locations.
    8. Installing a ground bracket at center tank DTSD location.
    9. Installing fuel quantity warning labels of the safe side 
harnesses.
    10. Modifying part number labels for the safe side harness.
    11. Bonding verification.
    12. Ensuring each safe side harness meets the requirements for 
minimum clearances from other airplane equipment.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition. The Goodrich 
service bulletin specifies that the actions must be accomplished within 
the ``applicable AD compliance period.''

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 404 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 2 airplanes of 
U.S. registry. The proposed actions would take about 9 work hours per 
airplane, at an average labor rate of $65 per work hour. For airplanes 
equipped with a Cinch rectangular connector, required parts would cost 
about $1,650 per airplane. For all other airplanes, required parts 
would cost about $1,500 per airplane. Based on these figures, the 
estimated cost of the proposed AD for U.S. operators is between $2,085 
and $2,235 per airplane.

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. 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.
    This rulemaking is promulgated under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, the FAA is charged with promoting 
safety 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 AD.

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

[[Page 75282]]

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-2004-19891; Directorate Identifier 2004-NM-
136-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by January 31, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes modified in accordance with Supplemental Type 
Certificate (STC) ST00127BO, certificated in any category.

Unsafe Condition

    (d) This AD was prompted by the results of fuel system reviews 
conducted by the STC holder. We are proposing this AD to prevent 
unsafe levels of current or energy from entering the fuel tank, due 
to hot short faults or threat conditions associated with the safe 
side harness assembly, which could result in a fire or explosion of 
the fuel tank.

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 12 months after the effective date of this AD, modify 
the safe side harness connectors at the tank penetrations and the 
digital transient suppression devices, in accordance with the 
Accomplishment Instructions of Goodrich Service Bulletin 737-300766-
28-2, Revision 2, dated July 28, 2004.

Parts Installation

    (g) As of the effective date of this AD, no person may install a 
safe side harness, Part Number 50357-01XX, on any airplane, unless 
that safe side harness has been modified in accordance with Goodrich 
Service Bulletin 737-300766-28-2, Revision 2, dated July 28, 2004.

Alternative Methods of Compliance (AMOCs)

    (h) The Manager, Boston 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.

    Issued in Renton, Washington, on December 3, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-27519 Filed 12-15-04; 8:45 am]
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