Document ID: FAA-2010-0035-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Boeing Company Model 747 400, 747 400D, and 747 400F Series Airplanes
Posted Date: 2010-02-11T05:00Z

[Federal Register: February 11, 2010 (Volume 75, Number 28)]
[Proposed Rules]               
[Page 6821-6823]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11fe10-5]                         

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Proposed Rules
                                                Federal Register
________________________________________________________________________

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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[[Page 6821]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0035; Directorate Identifier 2009-NM-066-AD]
RIN 2120-AA64

 
Airworthiness Directives; The Boeing Company Model 747-400, 747-
400D, and 747-400F Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
Model 747-400, 747-400D, and 747-400F series airplanes. This proposed 
AD would require installing a hot short protector (HSP) for the fuel 
quantity indicating system (FQIS) of the center fuel tank and, for 
certain airplanes, the horizontal stabilizer fuel tank. This proposed 
AD results from fuel system reviews conducted by the manufacturer. We 
are proposing this AD to prevent an electrical hot short from a source 
outside the FQIS to the densitometer wiring from causing failure of the 
FQIS densitometer resistors, which could result in an ignition source 
inside the center or horizontal stabilizer fuel tanks. An ignition 
source, in combination with flammable fuel vapors, could result in a 
fuel tank explosion and consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by March 29, 2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, 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, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; 
Internet https://www.myboeingfleet.com. You may review copies of the 
referenced service information at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information 
on the availability of this material at the FAA, call 425-227-1221 or 
425-227-1152.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Georgios Roussos, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6482; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0035; 
Directorate Identifier 2009-NM-066-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    The FAA has examined the underlying safety issues involved in 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'' 
(66 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

[[Page 6822]]

combination with a 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 a fuel tank explosion and consequent loss of the airplane.
    As part of SFAR 88 analysis, Boeing found that an electrical hot 
short from a source outside the fuel quantity indicating system (FQIS) 
to the densitometer wiring could result in an ignition source if the 
densitometer resistors failed while not covered by fuel. Installation 
of an electrical isolation device, a ``hot short protector'' (HSP), 
would protect the fuel densitometer for the horizontal stabilizer tank 
(HST) and the center wing tank (CWT) from exposure to unsafe energy 
levels. Failure of the FQIS densitometer resistors caused by a hot 
short could result in an ignition source inside the center or 
horizontal stabilizer fuel tanks. An ignition source, in combination 
with flammable fuel vapors, could result in a fuel tank explosion and 
consequent loss of the airplane.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 747-28A2266, Revision 1, 
dated December 10, 2009 (for airplanes with CWTs), and Boeing Alert 
Service Bulletin 747-28A2267, dated December 18, 2008 (for airplanes 
with HSTs). Those service bulletins describe procedures for installing 
an HSP in the CWT and the HST, as applicable. The installation involves 
re-terminating the existing wire bundle from the densitometer connector 
to the HSP, adding a new wire bundle that connects between the HSP and 
the densitometer connector, and installing the HSP and support bracket. 
For the HSP, the installation might also include reworking the lower 
center drip shield to provide clearance for the new wire connector 
backshell on the densitometer.
    Boeing Service Bulletin 747-28A2266, Revision 1, dated December 10, 
2009 (for airplanes with CWTs), and Boeing Alert Service Bulletin 747-
28A2267, dated December 18, 2008, refer to Cinch Service Bulletin 
CN1036-28-01, Revision C, dated January 18, 2007, as an additional 
source of service information for installing the HSP in the fuel tanks.

Other Related Rulemaking

    On April 28, 2008, we issued AD 2008-10-06, Amendment 39-15512 (73 
FR 25990, May 8, 2008), applicable to Boeing Model 747-400, -400D, and 
-400F series airplanes. That AD requires revising the maintenance 
program by incorporating new airworthiness limitations (AWLs) for fuel 
tank systems to satisfy SFAR 88 requirements. One of those AWLs, AWL 
28-AWL-23, is related to this proposed AD by including inspection of 
the bonding integrity during any subsequent replacement of the HSP.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously.

Costs of Compliance

    We estimate that this proposed AD would affect 80 airplanes of U.S. 
registry. The following table provides the estimated costs for U.S. 
operators to comply with this proposed AD.

                                             Table--Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                    Average
            Action                Work hours      labor rate        Parts           Cost per        Fleet cost
                                                   per hour                         product
----------------------------------------------------------------------------------------------------------------
Installation\1\..............  6 to 17.........          $85   $15,821 to       $16,331 to       $306,480 to
                                                                $30,650.         $32,095.         $2,567,600.
----------------------------------------------------------------------------------------------------------------
\1\ Work hours and parts costs depend on airplane configuration.

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 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 this 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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.

[[Page 6823]]

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2010-0035; Directorate Identifier 
2009-NM-066-AD.

Comments Due Date

    (a) We must receive comments by March 29, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to The Boeing Company Model 747-400, 747-
400D, and 747-400F series airplanes, certificated in any category; 
as identified in the service bulletins listed in paragraphs (c)(1) 
and (c)(2) of this AD.
    (1) Boeing Service Bulletin 747-28A2266, Revision 1, dated 
December 10, 2009.
    (2) Boeing Alert Service Bulletin 747-28A2267, dated December 
18, 2008.

Subject

    (d) Air Transport Association (ATA) of America Code 28: Fuel.

Unsafe Condition

    (e) This AD results from fuel system reviews conducted by the 
manufacturer. The Federal Aviation Administration is issuing this AD 
to prevent an electrical hot short from a source outside the Fuel 
Quantity Indicating System (FQIS) to the densitometer wiring from 
causing failure of the FQIS densitometer resistors, which could 
result in an ignition source inside the center or horizontal 
stabilizer fuel tanks. An ignition source, in combination with 
flammable fuel vapors, could result in a fuel tank explosion and 
consequent loss of the airplane.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Installation of Hot Short Protector

    (g) Within 60 months after the effective date of this AD: Do the 
applicable installations of the hot short protector (HSP) specified 
in paragraphs (g)(1) and (g)(2) of this AD.

    Note 1:
    Boeing Service Bulletin 747-28A2266, Revision 1, dated December 
10, 2009; and Boeing Alert Service Bulletin 747-28A2267, dated 
December 18, 2008; refer to Cinch Service Bulletin CN1036-28-01, 
Revision C, dated January 18, 2007, as an additional source of 
guidance for installing the HSP in the fuel tanks.

    (1) For all airplanes: Install the HSP in the center wing tank, 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-28A2266, Revision 1, dated December 10, 2009.
    (2) For airplanes identified in Boeing Alert Service Bulletin 
747-28A2267, dated December 18, 2008: Install the HSP in the 
horizontal stabilizer tank, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-28A2267, dated 
December 18, 2008.

Credit for Installation Previously Accomplished in Accordance With 
Previous Issue of Service Bulletin

    (h) Actions accomplished before the effective date of this AD 
according to Boeing Alert Service Bulletin 747-28A2266, dated 
December 18, 2008, are considered acceptable for compliance with the 
corresponding action specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. Send information to 
Attn: Georgios Roussos, Aerospace Engineer, Systems and Equipment 
Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 
Lind Avenue SW., Renton, Washington 98057-3356; telephone (425) 917-
6482; fax (425) 917-6590. Or, e-mail information to 9-ANM-Seattle-
ACO-AMOC-Requests@faa.gov.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.

    Issued in Renton, Washington, on February 4, 2010.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-2992 Filed 2-10-10; 8:45 am]
BILLING CODE 4910-13-P