
[Federal Register Volume 81, Number 85 (Tuesday, May 3, 2016)]
[Proposed Rules]
[Pages 26485-26487]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-09793]


 ========================================================================
 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.
 
 ========================================================================
 

  Federal Register / Vol. 81, No. 85 / Tuesday, May 3, 2016 / Proposed 
Rules  

[[Page 26485]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6139; Directorate Identifier 2015-NM-061-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and 
-900ER series airplanes. This proposed AD was prompted by fuel system 
reviews conducted by the manufacturer. This proposed AD would require 
modifying the fuel quantity indicating system (FQIS) to prevent 
development of an ignition source inside the center fuel tank due to 
electrical fault conditions. This proposed AD would also provide 
alternative actions for cargo airplanes. We are proposing this AD to 
prevent ignition sources inside the center fuel tank, which, 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 June 17, 2016.

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 by searching for and locating Docket No. FAA-2016-
6139; 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: Jon Regimbal, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6506; fax: 425-917-6590; email: Jon.Regimbal@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-2016-6139; 
Directorate Identifier 2015-NM-061-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. Subsequently, SFAR 88 was amended by: Amendment 21-82 
(67 FR 57490, September 10, 2002; corrected at 67 FR 70809, November 
26, 2002) and Amendment 21-83 (67 FR 72830, December 9, 2002; corrected 
at 68 FR 37735, June 25, 2003, to change ``21-82'' to ``21-83'').
    Among other actions, SFAR 88 requires certain type design approval 
(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 approval 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, combination of 
failures, and unacceptable (failure) experience. For all three failure 
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 fuel 
tanks, which, in combination with flammable

[[Page 26486]]

fuel vapors, could result in fuel tank explosions and consequent loss 
of the airplane.

Model 737NG FQIS Design

    The design of the in-tank FQIS components and wiring has the 
potential for a latent FQIS electrical fault condition inside the fuel 
tank combined with an electrical hot short condition connecting a high 
power source to the FQIS wiring to cause an ignition source in a fuel 
tank.
    Under the policy contained in FAA Policy Memo PS-ANM100-2003-112-15 
[http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/DC94C3A46396950386256D5E006AED11?OpenDocument&Highlight=anm-100-2003-112-15], the FAA determined that this ignition source risk combined 
with the fleet average flammability for the center wing tank on Model 
737-600, -700, -700C, -800, -900, and -900ER series airplanes created 
an unsafe condition for the center fuel tank. Applying that same 
policy, the FAA determined that due to a lower fleet average 
flammability, that same unsafe condition does not exist in the main 
(wing) tanks of these airplanes.

Related Rulemaking

    On March 21, 2016, we issued AD 2016-07-07, Amendment 39-18452 (81 
FR 19472, April 5, 2016), for certain Boeing Model 757-200, -200PF, -
200CB, and -300 series airplanes. AD 2016-07-07 requires similar 
actions to those proposed in this NPRM. AD 2016-07-07 addressed the 
numerous public comments that were submitted on the proposal.

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 to prevent 
development of an ignition source inside the center fuel tank due to 
electrical fault conditions. As an alternative for cargo airplanes, 
this proposed AD would provide the alternative to modify the airplane 
by separating FQIS wiring routed between the FQIS processor and the 
center fuel tank, provided repetitive BITE checks (checks of built-in 
test equipment) of the FQIS are also performed.

Costs of Compliance

    There are approximately 1,393 U.S.-registered Model 737-600, -700, 
-700C, -800, -900, and -900ER series airplanes in service. All of those 
airplanes are currently operated as passenger airplanes. Beginning with 
line number 2620, however, Boeing has delivered airplanes with 
flammability reductions means (FRM)/nitrogen generation system (NGS) 
installed. We estimate that 831 affected airplanes on the U.S. Register 
were delivered without FRM installed, but we do not know the number of 
airplanes that have had FRM installed post-production. However, because 
of the requirement in 14 CFR 121.1117 to install FRM on U.S. air-
carrier passenger airplanes by the end of 2017, it is likely that no 
U.S. airplanes would actually be affected by this proposed AD. For any 
affected airplane, we estimate the following costs to comply with this 
proposed AD:

                                        Estimated Costs--Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                 Action                                Labor cost                  Parts cost        product
----------------------------------------------------------------------------------------------------------------
Modification............................  1,200 work-hours x $85 per hour =           $200,000         $302,000
                                           $102,000.
----------------------------------------------------------------------------------------------------------------


                                      Estimated Costs--Alternative Actions
----------------------------------------------------------------------------------------------------------------
               Action                            Labor cost                Parts cost        Cost per product
----------------------------------------------------------------------------------------------------------------
BITE check..........................  1 work-hour x $85 per hour = $85              $0   $85 per check (4 checks
                                       per check.                                         per year, $340 per
                                                                                          year).
Wire separation.....................  230 work-hours x $85 per hour =          $10,000   $29,550.
                                       $19,550.
----------------------------------------------------------------------------------------------------------------

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.

[[Page 26487]]

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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

The Boeing Company: Docket No. FAA-2016-6139; Directorate Identifier 
2015-NM-061-AD.

(a) Comments Due Date

    We must receive comments by June 17, 2016.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any 
category, excluding airplanes equipped with a flammability reduction 
means (FRM) approved by the FAA as compliant with the Fuel Tank 
Flammability Reduction (FTFR) rule (73 FR 42444, July 21, 2008) 
requirements of section 25.981(b) or section 26.33(c)(1) of the 
Federal Aviation Regulations (14 CFR 25.981(b) or 14 CFR 
26.33(c)(1)).

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent ignition sources 
inside the center fuel tank, which, in combination with flammable 
fuel vapors, could result in a fuel tank explosion and consequent 
loss of the airplane.

(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 
fuel quantity indicating system (FQIS) to prevent development of an 
ignition source inside the center fuel tank due to electrical fault 
conditions, using a method approved in accordance with the 
procedures specified in paragraph (i) of this AD.

(h) Alternative Actions for Cargo Airplanes

    For airplanes used exclusively for cargo operations: As an 
alternative to the requirements of paragraph (g) of this AD, do the 
actions specified in paragraphs (h)(1) and (h)(2) of this AD, using 
methods approved in accordance with the procedures specified in 
paragraph (i) of this AD. To exercise this alternative, operators 
must perform the first inspection required under paragraph (h)(1) of 
this AD within 6 months after the effective date of this AD. To 
exercise this alternative for airplanes returned to service after 
conversion of the airplane from a passenger configuration to an all-
cargo configuration more than 6 months after the effective date of 
this AD, operators must perform the first inspection required under 
paragraph (h)(1) of this AD prior to further flight after the 
conversion.
    (1) Within 6 months after the effective date of this AD, record 
the existing fault codes stored in the FQIS processor and then do a 
BITE check (check of built-in test equipment) of the FQIS. If any 
nondispatchable fault code is recorded prior to the BITE check or as 
a result of the BITE check, before further flight, do all applicable 
repairs and repeat the BITE check until a successful test is 
performed with no nondispatchable faults found, using a method 
approved in accordance with the procedures specified in paragraph 
(i) of this AD. Repeat these actions thereafter at intervals not to 
exceed 650 flight hours. Modification as specified in paragraph 
(h)(2) of this AD does not terminate the repetitive BITE check 
requirement of this paragraph.
    (2) Within 60 months after the effective date of this AD, modify 
the airplane by separating FQIS wiring that runs between the FQIS 
processor and the center tank wing spar penetrations, including any 
circuits that might pass through a main fuel tank, from other 
airplane wiring that is not intrinsically safe, using methods 
approved in accordance with the procedures specified in paragraph 
(i) of this AD.

(i) Alternative Methods of Compliance (AMOCs)

    (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. 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 paragraph (j) 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.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by the Boeing Commercial Airplanes Organization 
Designation Authorization (ODA) that has been authorized by the 
Manager, Seattle ACO, to make those findings. To be approved, the 
repair method, modification deviation, or alteration deviation must 
meet the certification basis of the airplane, and the approval must 
specifically refer to this AD.

(j) Related Information

    For more information about this AD, contact Jon Regimbal, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle 
Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, 
WA 98057-3356; phone: 425-917-6506; fax: 425-917-6590; email: 
Jon.Regimbal@faa.gov.

    Issued in Renton, Washington, on April 15, 2016.
Victor Wicklund,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-09793 Filed 5-2-16; 8:45 am]
BILLING CODE 4910-13-P


