Document ID: FAA-2008-0640-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 747-400, 747-400D, and 747-400F Series Airplanes
Posted Date: 2008-06-18T04:00Z

[Federal Register: June 18, 2008 (Volume 73, Number 118)]
[Proposed Rules]               
[Page 34663-34665]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18jn08-16]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0640; Directorate Identifier 2008-NM-070-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing 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 
certain Boeing Model 747-400, 747-400D, and 747-400F series airplanes. 
This proposed AD would require installing an extension tube to the 
existing pump discharge port of the scavenge pump on the outboard side 
of the center fuel tank in the main fuel tank 2. This AD 
results from fuel system reviews conducted by the manufacturer. We are 
issuing this AD to prevent a fire or explosion in the fuel tank and 
consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by August 4, 2008.

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-

[[Page 34664]]

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 AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

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: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; 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-2008-0640; 
Directorate Identifier 2008-NM-070-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 
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 fuel tank explosions and consequent loss of the airplane.
    As a result of the SFAR 88 design review activity, Boeing has found 
that certain single failure modes within the electric scavenge pump 
could cause heating and sparking, which could create a potential 
ignition source inside the main fuel tank 2. This condition, 
if not corrected, could result in a fire or explosion in the main fuel 
tank 2 and consequent loss of the airplane.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 747-28-
2260, dated March 13, 2008. The service bulletin describes procedures 
for installing an extension tube to the existing pump discharge port of 
the scavenge pump on the outboard side of the center fuel tank in the 
main fuel tank 2.

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(se) same type 
design(s). 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 31 airplanes of U.S. 
registry. We also estimate that it would take about 16 work-hours per 
product to comply with this proposed AD. The average labor rate is $80 
per work-hour. Required parts would cost about $900 per product. Based 
on these figures, we estimate the cost of this proposed AD to the U.S. 
operators to be $67,580 fleet cost, or $2,180 per product.

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.

[[Page 34665]]

    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, 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 AD:

Boeing: Docket No. FAA-2008-0640; Directorate Identifier 2008-NM-
070-AD.

Comments Due Date

    (a) We must receive comments by August 4, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-400, 747-400D, and 747-
400F series airplanes, certificated in any category; as identified 
in Boeing Special Attention Service Bulletin 747-28-2260, dated 
March 13, 2008.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent a fire or explosion 
in the fuel tank and consequent loss of the airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Installation

    (f) Within 60 months after the effective date of this AD, 
install an extension tube to the existing pump discharge port of the 
scavenge pump on the outboard side of the center fuel tank in the 
main fuel tank 2, in accordance with the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 747-28-
2260, dated March 13, 2008.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office 
(SACO), FAA, ATTN: Sulmo Mariano, Aerospace Engineer, Propulsion 
Branch, ANM-140S, FAA, SACO, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6501; fax (425) 917-6590; 
has the authority to approve AMOCs for this AD, if requested using 
the procedures found in 14 CFR 39.19.
    (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 appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on June 6, 2008.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-13714 Filed 6-17-08; 8:45 am]

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