[Federal Register Volume 73, Number 9 (Monday, January 14, 2008)]
[Proposed Rules]
[Pages 2204-2206]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-384]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0013; Directorate Identifier 2007-NM-230-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727-200 Series Airplanes 
Equipped With an Auxiliary Fuel Tank System Installed in Accordance 
With Supplemental Type Certificate SA1350NM

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 727-200 series airplanes. This proposed AD 
would require deactivation of auxiliary fuel tank systems installed in 
accordance with Supplemental Type Certificate (STC) SA1350NM. This 
proposed AD results from fuel tank system reviews conducted by the 
manufacturer that identified potential unsafe conditions for which the 
manufacturer has not provided corrective actions. We are proposing this 
AD to prevent 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.

DATES: We must receive comments on this proposed AD by February 28, 
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-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.

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: Jeff Janusz, Aerospace Engineer, 
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, Kansas 67209; telephone (316) 946-4148; fax (316) 
946-4107.

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-2008-0013; 
Directorate Identifier 2007-NM-230-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'' 
(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) design 
approval) holders to substantiate that their fuel tank systems can 
prevent ignition sources in the fuel tanks. This requirement applies to 
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, 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.

[[Page 2205]]

Supplemental Type Certificate (STC) SA1350NM for DTAA, Inc., Auxiliary 
Fuel Tank System

    The auxiliary fuel tank system STC consists of two fuel tank 
systems, a forward tank system consisting of 5 cells and an aft tank 
system consisting of 3 cells. Each cell or individual tank is of a 
double wall cylindrical design. All auxiliary fuel tank system tanks 
are emptied and vented into the airplane center wing tank using bleed 
air pressure supplied from the No. 1 (left hand) engine. All auxiliary 
fuel tank system tanks use some type of electrical fuel quantity 
indication system (FQIS), flight deck control and annunciation panels, 
bleed air pressure regulators, vents, bleed air, and transfer valves, 
pressure switches, float level switches, and associated electrical 
wiring connections and electrical bonding methods.

FAA's Findings

    During the SFAR 88 safety assessment, it was determined that the 
auxiliary fuel tank system FQIS requires wire separation or other means 
to preclude any adjacent high power wires from shorting or inducing 
high electrical energy levels into the auxiliary fuel tank system or 
airplane fuel tank system. Additionally, the auxiliary fuel tank system 
fuel transfer valves were not previously tested or shown to be 
intrinsically safe from producing electrical arcing or explosion 
hazards while in the presence of fuel vapors; therefore, re-
certification or relocation of these valves are mandated. Finally, STC 
SA1350NM has been categorized by the FAA as being a high flammability 
exposure installation, based on the internal fuselage location of the 
auxiliary fuel tank system. A means to insure low flammability exposure 
or to mitigate the effects of high flammability exposure time is 
mandated.
    DTAA, Inc., has not provided the service information required under 
SFAR 88 that would correct these conditions; therefore, we must mandate 
the deactivation of all DTAA, Inc., auxiliary fuel tank systems 
installed in accordance with STC SA1350NM.
    If operators do not wish to deactivate their auxiliary fuel tanks, 
we will consider requests for alternative methods of compliance 
(AMOCs).
    Once an operator has deactivated the tank as required by this AD, 
the operator might wish to remove the tank. This would require a 
separate design approval, if an approved tank removal procedure does 
not exist.

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 products 
of this same type design. For this reason, we are proposing this AD, 
which would require deactivation to prevent usage of the auxiliary fuel 
tank system installed in accordance with STC SA1350NM.

Explanation of Compliance Time

    In most ADs, we adopt a compliance time allowing a specified amount 
of time after the AD's effective date. In this case, however, the FAA 
has already issued regulations that require operators to revise their 
maintenance/inspection programs to address fuel tank safety issues. The 
compliance date for these regulations is December 16, 2008. To provide 
for coordinated implementation of these regulations and this proposed 
AD, we are using this same compliance date in this proposed AD.

Costs of Compliance

    The following table provides the estimated costs for the 25 U.S.-
registered airplanes to comply with this proposed AD. Based on these 
figures, the estimated costs for U.S. operators could be as high as 
$162,000 to prepare and report the deactivation procedures, and $90,000 
to deactivate the tank.

                                                 Estimated Costs
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                                                        Average labor                               Individual
                Action                   Work hours     rate per hour            Parts                 cost
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Report...............................               1             $80  None.....................             $80
Preparation of tank deactivation                   80              80  None.....................           6,400
 procedure.
Physical tank deactivation...........              30              80  1,200....................           3,600
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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 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 under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. 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:

[[Page 2206]]

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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

DTAA, Inc.: Docket No. FAA-2008-0013; Directorate Identifier 2007-
NM-230-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by February 
28, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 727-200 series airplanes, 
certificated in any category and equipped with an auxiliary fuel 
tank system installed in accordance with Supplemental Type 
Certificate SA1350NM.

Unsafe Condition

    (d) This AD results from fuel tank system reviews conducted by 
the manufacturer. We are issuing this AD to prevent 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.

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.

Report

    (f) Within 45 days after the effective date of this AD, submit a 
report to the Manager, Wichita Aircraft Certification Office (ACO), 
FAA. The report must include the information listed in paragraphs 
(f)(1) and (f)(2) of this AD. Under the provisions of the Paperwork 
Reduction Act (44 U.S.C. 3501, et seq.), the Office of Management 
and Budget (OMB) has approved the information collection 
requirements contained in this AD, and assigned OMB Control Number 
2120-0056.
    (1) The airplane registration and serial number.
    (2) The usage frequency in terms of total number of flights per 
year and total number of flights per year for which the auxiliary 
fuel tank system is used.

Prevent Usage of Auxiliary Fuel Tank

    (g) On or before December 16, 2008, deactivate the auxiliary 
fuel tank system, in accordance with a deactivation procedure 
approved by the Manager of the Wichita ACO. Any auxiliary fuel tank 
system component that remains on the airplane must be secured and 
must have no effect on the continued operational safety and 
airworthiness of the airplane. Deactivation may not result in the 
need for additional Instructions for Continued Airworthiness (ICA).

    Note 1: Appendix A of this AD provides criteria that must be 
included in the deactivation procedure. The proposed deactivation 
procedures should be submitted to the Wichita ACO as soon as 
possible to ensure timely review and approval, prior to 
implementation.


    Note 2: For technical information, contact Steve Forness, DTAA, 
Inc., 101 Deer Meadow Court, St. Charles, Missouri 63304, (636) 928-
9606, fax (314) 749-7513.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Wichita ACO, FAA, has the authority to 
approve AMOCs for this AD, if requested in accordance with 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.

Appendix A--Deactivation Criteria

    The auxiliary fuel tank system deactivation procedure required 
by paragraph (g) of this AD should address the following actions.
    (1) Permanently drain the auxiliary fuel tank system tanks, and 
clear them of fuel vapors to eliminate the possibility of out-
gassing of fuel vapors from the emptied auxiliary tank.
    (2) Disconnect all auxiliary fuel tank system electrical 
connections from the fuel quantity indication system (FQIS), float, 
pressure and transfer valves and switches, and all other electrical 
connections required for auxiliary fuel tank system operation, and 
stow them at the auxiliary fuel tank interface.
    (3) Disconnect all auxiliary fuel tank system bleed-air 
connections, cap them at the bleed air source, and secure them.
    (4) Disconnect all auxiliary fuel tank system fuel supply and 
fuel vent plumbing interfaces with airplane original equipment 
manufacturer (OEM) fuel tanks, cap them at the airplane tank side, 
and secure them. All disconnected auxiliary fuel tank system vent 
systems must not alter the OEM fuel tank vent system configuration 
or performance. All empty auxiliary fuel tank system tanks must be 
vented to eliminate the possibility of structural deformation during 
cabin decompression. The configuration must not permit the 
introduction of fuel vapor into any compartments of the airplane.
    (5) Pull and collar all circuit breakers used to operate the 
auxiliary fuel tank system.
    (6) Revise the weight and balance document, if required, and 
obtain FAA approval.
    (7) Amend the applicable sections of the applicable Airplane 
Flight Manual (AFM) to indicate that the auxiliary fuel tank system 
is deactivated. Remove auxiliary fuel tank system operating 
procedures to ensure that only the OEM fuel system operational 
procedures are contained in the AFM. Amend the Limitations Section 
of the AFM to indicate that the AFM Supplement for the STC is not in 
effect. Place a placard in the flight deck indicating that the 
auxiliary fuel tank system is deactivated. The AFM revisions 
specified in this paragraph may be accomplished by inserting a copy 
of this AD into the AFM.
    (8) Amend the applicable sections of the applicable airplane 
maintenance manual to remove auxiliary fuel tank system maintenance 
procedures.
    (9) After the auxiliary fuel tank system is deactivated, 
accomplish procedures such as leak checks, pressure checks, and 
functional checks deemed necessary before returning the airplane to 
service. These procedures must include verification that the basic 
airplane OEM FQIS, fuel distribution, and fuel venting systems 
function properly and have not been adversely affected by 
deactivation of the auxiliary fuel tank system.
    (10) Include with the proposed deactivation procedures any 
relevant information or additional steps that are deemed necessary 
by the operator to comply with the deactivation of the auxiliary 
fuel tank system and return of the airplane to service.

    Issued in Renton, Washington, on December 21, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

[FR Doc. E8-384 Filed 1-11-08; 8:45 am]
BILLING CODE 4910-13-P