Document ID: FAA-2012-0187-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Boeing Co. Airplanes
Posted Date: 2012-03-01T05:00Z

[Federal Register Volume 77, Number 41 (Thursday, March 1, 2012)]
[Proposed Rules]
[Pages 12506-12508]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-4931]

 ========================================================================
 Proposed Rules
                                                 Federal Register
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 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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 

  Federal Register / Vol. 77, No. 41 / Thursday, March 1, 2012 / 
Proposed Rules  

[[Page 12506]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0187; Directorate Identifier 2011-NM-094-AD]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company 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 The Boeing Company Model 757 airplanes. This proposed AD was 
prompted by fuel system reviews conducted by the manufacturer. This 
proposed AD would require modifying the fuel quantity indication system 
(FQIS) wiring or fuel tank systems to prevent development of an 
ignition source inside the center fuel tank. We are proposing this AD 
to prevent ignition sources inside the center fuel tank, which, in 
combination with flammable fuel vapors, could result in fuel tank 
explosions and consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by April 30, 2012.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, 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: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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 (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Tak Kobayashi, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 425-
917-6499; fax: 425-917-6590; email: takahisa.kobayashi@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2012-0187; 
Directorate Identifier 2011-NM-094-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, a combination of 
failures, and unacceptable 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 proposed AD 
are necessary to reduce the potential of ignition sources inside the 
center fuel tank, which has been identified to have a high flammability 
exposure. Ignition sources inside the center fuel tank, in combination 
with flammable fuel vapors, could result in fuel tank explosions and 
consequent loss of the airplane.
    The combination of a latent failure within the center fuel tank and 
a subsequent single failure of the fuel quantity indicating system 
(FQIS) wiring or components outside the fuel tank can cause development 
of an

[[Page 12507]]

ignition source inside the center fuel tank. Latent in-tank failures, 
including corrosion/deposits at wire terminals, conductive debris on 
fuel system probes, wires or probes contacting the tank structure, and 
wire faults, could create a conductive path inside the center fuel 
tank. Out-tank single failures including hot shorts in airplane wiring 
and/or the FQIS processor could result in electrical energy being 
transmitted into the center fuel tank via the FQIS wiring. The 
electrical energy, if combined with a latent in-tank failure, could be 
sufficient to create an ignition source inside the center fuel tank, 
which, combined with flammable fuel vapors could result in a 
catastrophic fuel tank explosion.

SFAR 88 and Fuel Tank Flammability Reduction Rule

    The National Transportation Safety Board (NTSB) determined that the 
combination of a latent failure inside the center fuel tank and a 
subsequent single failure of the FQIS wiring or components outside the 
fuel tank was the most likely ignition source inside the center fuel 
tank that resulted in the TWA Flight 800 explosion. After the TWA 800 
accident, we issued AD 99-03-04, Amendment 39-11018 (64 FR 4959, 
February 2, 1999), and AD 98-20-40, Amendment 39-10808 (63 FR 52147, 
September 30, 1998), mandating separation of the FQIS wiring that 
penetrates the fuel tank from high power wires and circuits on the 
classic Boeing 737 and 747 airplanes. Those ADs resulted in 
installation of Transient Suppression Units (TSUs), Transient 
Suppression Devices (TSDs), or Isolated Fuel Quantity Transmitter 
(IFQT) as a method of compliance with the AD requirements.
    After we issued those ADs, the findings from the SFAR 88 review 
showed that most transport category airplanes with high flammability 
fuel tanks needed TSUs, TSDs, or IFQTs to prevent electrical energy 
from entering the fuel tanks via the FQIS wiring in the event of a 
latent failure in combination with a single failure.
    Installation of those FQIS protection devices, however, was 
determined unnecessary on those airplanes that are required to comply 
with the ``Reduction of Fuel Tank Flammability in Transport Category 
Airplanes'' rule (73 FR 42444, July 21, 2008), referred to as the Fuel 
Tank Flammability Reduction (FTFR) rule. The FTFR rule requires 
incorporation of a flammability reduction means (FRM) that converts 
high flammability fuel tanks into low flammability fuel tanks for 
certain airplane models. Therefore, the unsafe condition identified by 
SFAR 88 is mitigated by incorporation of an FRM, as discussed in the 
FTFR rule.
    This proposed AD is intended to address the unsafe condition 
associated with the FQIS wiring that penetrates the center fuel tank 
for all Boeing Model 757 airplanes that are not subject to the 
requirements of the FTFR rule. This proposed AD would apply to 
airplanes operated in all-cargo service and airplanes operated under 
Title 14 Code of Federal Regulations (CFR) part 91, since those 
airplanes are not subject to the requirements of the FTFR rule. Also, 
this proposed AD would apply to airplanes for which the State of 
Manufacture issued the original certificate of airworthiness or export 
airworthiness approval prior to January 1, 1992, since those airplanes 
are also not subject to the requirements of the FTFR rule. However, as 
explained in paragraph 2-5.a. of Advisory Circular 120-98, ``Operator 
Requirements for Incorporation of Fuel Tank Flammability Reduction 
Requirements,'' dated May 7, 2009, to operate a pre-1992 airplane in 
passenger service after December 26, 2017, operators must incorporate 
an FRM that meets the requirements of Sec.  26.33(c) before that date. 
For such airplanes on which an FRM is incorporated, further compliance 
with this proposed AD is not required.
    The nitrogen generating system (NGS) being developed by Boeing to 
meet the FTFR rule addresses the unsafe condition of this AD, as well 
as providing other safety improvements. Paragraph (h) of this proposed 
AD provides that, for operators not required to comply with the FTFR 
rule, electing to comply with the FTFR rule would be an acceptable 
method of addressing the unsafe condition.
    As discussed in the FTFR rule, the FAA recognized that separate 
airworthiness actions would be initiated to address the remaining fuel 
system safety issues for airplanes for which an FRM is not required. We 
have notified design approval holders that service instructions to 
support introduction of FQIS protection are now necessary for fuel 
tanks that are not required to be modified with an FRM by the FTFR 
rule. To date we have not received any service information from Boeing 
addressing this specific threat; therefore, we are proceeding with this 
proposal, which would require modifications using methods approved by 
the Manager of the Seattle Aircraft Certification Office.
    We plan similar actions for those Boeing and Airbus airplanes with 
similar FQIS vulnerabilities that are not affected by the FTFR rule.

FAA's Determination

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

Proposed AD Requirements

    This proposed AD would require modifying the FQIS wiring or fuel 
tank systems to prevent development of an ignition source inside the 
center fuel tank.

Costs of Compliance

    We estimate that this proposed AD affects 352 airplanes of U.S. 
registry. We have been advised that some of those airplanes are subject 
to the requirements of the FTFR rule and therefore are excluded from 
the requirements of this AD.
    Because the manufacturer has not yet developed a modification 
commensurate with the actions specified by this proposed AD, we cannot 
provide specific information regarding the required number of work 
hours or the cost of parts to do the proposed modification. In 
addition, modification costs will likely vary depending on the operator 
and the airplane configuration. The proposed compliance time of 60 
months should provide ample time for the development, approval, and 
installation of an appropriate modification.
    Based on similar modifications, however, we can provide some 
estimated costs for the proposed modification in this NPRM. The 
modifications mandated by AD 99-03-04, Amendment 39-11018 (64 FR 4959, 
February 2, 1999), and AD 98-20-40, Amendment 39-10808 (63 FR 52147, 
September 30, 1998), for the classic Boeing Model 737 and 747 airplanes 
(i.e., TSD, TSU, IFQT) are not available for Boeing Model 757 
airplanes. But, based on the costs associated with those modifications, 
we estimate the cost of this new proposed modification to be no more 
than $100,000 per airplane. The Honeywell FQIS may need additional 
modifications, which may cost as much as $100,000 per airplane. The 
cost impact of the proposed AD therefore is estimated to be between 
$100,000 and $200,000 per airplane.
    As indicated earlier in this preamble, we specifically invite the 
submission of comments and other data regarding the costs of this 
proposed AD.

[[Page 12508]]

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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

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.

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2012-0187; Directorate Identifier 
2011-NM-094-AD.

(a) Comments Due Date

    We must receive comments by April 30, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 757-200, -200PF, -
200CB, and -300 series airplanes; certificated in any category; for 
which compliance with 14 CFR 121.1117(d), 125.509(d), or 129.117(d) 
is not required; regardless of the date of issuance of the original 
certificate of airworthiness or export airworthiness approval.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 7397: Engine fuel system wiring.

(e) Unsafe Condition

    This AD was prompted by fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent development of an 
ignition source inside the center fuel tank caused by a latent in-
tank failure combined with electrical energy transmitted into the 
center fuel tank via the fuel quantity indicating system (FQIS) 
wiring due to a single out-tank failure.

(f) Compliance

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

(g) Modification

    Within 60 months after the effective date of this AD, modify the 
FQIS wiring or fuel tank systems to prevent development of an 
ignition source inside the center fuel tank, in accordance with a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA.

    Note 1 to paragraph (g) of this AD: After accomplishment of the 
actions required by paragraph (g) of this AD, maintenance and/or 
preventive maintenance under 14 CFR part 43 is permitted provided 
the maintenance does not result in changing the AD-mandated 
configuration (reference 14 CFR 39.7).

(h) Optional Installation of Flammability Reduction Means

    As an alternative to the requirements of paragraph (g) of this 
AD, operators may elect to comply with the requirements of 14 CFR 
121.1117 or 14 CFR 125.509 or 14 CFR 129.117 (not including the 
exclusion of cargo airplanes in Sections 121.1117(j), 129.117(j), 
and 125.509(j)). Following this election, failure to comply with 
Sections 121.1117, 129.117, and 125.509 is a violation of this AD.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO, FAA, has the authority to approve 
AMOCs for this AD, if requested using the procedures found in 14 CFR 
39.19. In accordance with 14 CFR 39.19, send your request to your 
principal inspector or local Flight Standards District Office, as 
appropriate. If sending information directly to the manager of the 
ACO, send it to the attention of the person identified in the 
Related Information section of this AD. Information may be emailed 
to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(j) Related Information

    For more information about this AD, contact Tak Kobayashi, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle 
Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; phone: 425-917-6499; fax: 425-917-6590; 
email: takahisa.kobayashi@faa.gov.

    Issued in Renton, Washington, on February 21, 2012.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-4931 Filed 2-29-12; 8:45 am]
BILLING CODE 4910-13-P