[Federal Register Volume 73, Number 1 (Wednesday, January 2, 2008)]
[Proposed Rules]
[Pages 84-87]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-25482]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0389; Directorate Identifier 2007-NM-222-AD]
RIN 2120-AA64


Airworthiness Directives; Various Transport Category Airplanes 
Equipped With Auxiliary Fuel Tanks Installed in Accordance With Certain 
Supplemental Type Certificates

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

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for various transport category airplanes. This proposed AD would 
require deactivation of Southeast Aero-Tek, Inc., auxiliary fuel tanks. 
This proposed AD results from fuel system reviews conducted by the 
manufacturer, which 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 19, 
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: Robert Bosak, Aerospace Engineer, 
Propulsion and Services Branch, ACE-118A, FAA, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Boulevard, Suite 
460, Atlanta, Georgia 30349; telephone (770) 703-6094; fax (770) 703-
6097.

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-2007-0389; 
Directorate Identifier 2007-NM-222-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) 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

[[Page 85]]

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 proposed 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.

Supplemental Type Certificates (STCs) for Southeast Aero-Tek, Inc., 
Auxiliary Fuel Tanks

    The auxiliary fuel tank STCs on affected airplanes are a double-
walled cylindrical type design. The double-walled cylindrical tanks use 
pneumatic air pressure to empty into the airplane's center wing tank. 
All auxiliary tanks use some type of electrical fuel quantity 
indication system (FQIS), flight deck control and annunciation panels, 
float level switches, valves and venting systems, electrical wiring 
connections in the dry bay area, and electrical bonding methods.

FAA's Findings

    During the SFAR 88 safety assessment, it was determined that the 
Southeast Aero-Tek, Inc., FQIS and float level switch did not meet 
intrinsically safe electrical energy levels as described in the 
guidelines of Advisory Circular (AC) 25.981-1B, ``Fuel Tank Ignition 
Source Prevention Guidelines.'' Southeast Aero-Tek, Inc., identified 
potential ignition sources resulting from a combination of single and 
latent failures for the Southeast Aero-Tek, Inc., fuel tank subsystems. 
To prevent high electrical energy levels from the FQIS and float level 
switch from entering the auxiliary fuel tank, we have determined that 
the appropriate solution for continued use is a combination of actions. 
First, installing a transient suppression device (TSD) on FQIS and 
float level switches would be needed. In order to maximize wire 
separation, the TSD must be installed as close as possible to the 
points where the FQIS and float level switch wires exit the TSD and 
enter the auxiliary tank. Other actions might include replacing high-
energy FQISs, and float level switches that are impractical for TSD 
application with intrinsically safe FQISs providing wire separation, 
conducting a one-time inspection and/or replacing aging float level 
switch conduit assemblies, periodically inspecting the external dry bay 
system components and wires, and testing the integrity of bonding 
resistances.
    Southeast Aero-Tek, Inc., has not fully provided the service 
information required under SFAR 88 that would correct these conditions; 
therefore, we must mandate the deactivation of all Southeast Aero-Tek, 
Inc., auxiliary fuel tanks.
    If operators do not wish to deactivate their auxiliary fuel tanks, 
we will consider requests for alternative methods of compliance 
(AMOCs). The most likely requests would be to allow continued use of 
the tanks by showing compliance with SFAR 88. This would involve 
obtaining STCs to modify the auxiliary fuel tank systems and developing 
maintenance procedures to address the safety issues identified above.
    Once an operator has deactivated a tank as proposed by this NPRM, 
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 auxiliary fuel 
tanks.

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 37 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 
$239,760 to prepare and report the deactivation procedures, and 
$133,200 to deactivate tanks.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                   Average labor
             Action                 Work hours     rate per hour          Parts              Individual cost
----------------------------------------------------------------------------------------------------------------
Report..........................               1             $80  None................  $80, per STC.
Preparation of tank deactivation              80              80  None................  6,400, per STC.
 procedure.
Physical tank deactivation......              30              80  1,200...............  3,600, per airplane.
----------------------------------------------------------------------------------------------------------------

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:

[[Page 86]]

    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:

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):

Various Transport Category Airplanes: Docket No. FAA-2007-0389; 
Directorate Identifier 2007-NM-222-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by February 
19, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to airplanes, certificated in any category, 
and equipped with auxiliary fuel tanks installed in accordance with 
specified supplemental type certificates (STCs), as identified in 
Table 1 of this AD.

                      Table 1.--Affected Airplanes
------------------------------------------------------------------------
               Airplanes                      Auxiliary tank STC(s)
------------------------------------------------------------------------
Boeing Model 727-100 series airplanes..  ST01587AT.
Boeing Model 727-200 and -200F series    SA2033NM, SA1474SO
 airplanes.
McDonnell Douglas Model DC-9-14          SA1334NM
 airplanes.
McDonnell Douglas Model DC-9-32, DC-9-   SA1710SO and SA1358NM
 32 (VC-9C), DC-9-32F, DC-9-33F, and DC-
 9-32F (C-9A, C-9B) airplanes.
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer, which identified potential unsafe conditions for which 
the manufacturer has not provided corrective actions. 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, Atlanta 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 auxiliary tank STC number 
installed.
    (2) The usage frequency in terms of total number of flights per 
year and total number of flights per year for which the auxiliary 
tank is used.

Prevent Usage of Auxiliary Fuel Tanks

    (g) On or before December 16, 2008, deactivate the auxiliary 
fuel tanks, in accordance with a deactivation procedure approved by 
the Manager of the Atlanta ACO. Any auxiliary tank 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.

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


    Note 2: For technical information, contact Randy Smith, 
President, Southeast Aero-Tek, Inc., 675 Oleander Drive, Merritt 
Island, Florida 32952; telephone (321) 453-7876; fax (321) 453-7872.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Atlanta 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 deactivation procedure required by 
paragraph (g) of this AD should address the following actions.
    (1) Permanently drain auxiliary fuel 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 electrical connections from the fuel quantity 
indication system (FQIS), fuel pumps if applicable, float switches, 
and all other electrical connections required for auxiliary tank 
operation, and stow them at the auxiliary tank interface.
    (3) Disconnect all pneumatic connections if applicable, cap them 
at the pneumatic source, and secure them.
    (4) Disconnect all fuel feed and fuel vent plumbing interfaces 
with airplane original equipment manufacturer (OEM) tanks, cap them 
at the airplane tank side, and secure them in accordance with a 
method approved by the FAA; one approved method is specified in AC 
25-8 Fuel Tank Flammability Minimization. In order to eliminate the 
possibility of structural deformation during cabin decompression, 
leave open and secure the disconnected auxiliary fuel tank vent 
lines.
    (5) Pull and collar all circuit breakers used to operate the 
auxiliary tank.
    (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 is 
deactivated. Remove auxiliary fuel tank 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 tank is 
deactivated. The AFM revisions specified in

[[Page 87]]

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 tank maintenance procedures.
    (9) After the auxiliary fuel tank is deactivated, accomplish 
procedures such as leak checks and pressure checks deemed necessary 
before returning the airplane to service. These procedures must 
include verification that the airplane FQIS and fuel distribution 
systems have not been adversely affected.
    (10) Include with the operator's proposed procedures any 
relevant information or additional steps that are deemed necessary 
by the operator to comply with the deactivation and return the 
airplane to service.

    Issued in Renton, Washington, on December 19, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

 [FR Doc. E7-25482 Filed 12-31-07; 8:45 am]
BILLING CODE 4910-13-P