Document ID: FAA-2008-1325-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 727-281 Airplanes Equipped With Auxiliary Fuel Tanks Installed in Accordance With Supplemental Type Certificate SA3449NM
Posted Date: 2008-12-23T05:00Z

[Federal Register: December 23, 2008 (Volume 73, Number 247)]
[Proposed Rules]               
[Page 78675-78678]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23de08-25]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1325; Directorate Identifier 2008-NM-157-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 727-281 Airplanes Equipped 
With Auxiliary Fuel Tanks Installed in Accordance With Supplemental 
Type Certificate SA3449NM

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 727-281 airplanes. This proposed AD would 
require deactivation of Rogerson Aircraft Corporation auxiliary fuel 
tanks. This proposed AD results from fuel system reviews conducted by 
the manufacturer, which identified potential unsafe conditions but has 
not

[[Page 78676]]

provided associated 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 6, 
2009.

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: Serj Harutunian, Aerospace Engineer, 
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; 
telephone (562) 627-5254; fax (562) 627-5210.

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-2008-1325; 
Directorate Identifier 2008-NM-157-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 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.

Rogerson Auxiliary Fuel Tank STCs

    The auxiliary fuel tank STCs on affected airplanes are cylindrical 
and double walled. These tanks use pneumatic air pressure to empty into 
the airplane 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 
Rogerson Aircraft Corporation 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. Rogerson identified potential ignition 
sources resulting from a combination of single and latent failures for 
the Rogerson 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 (depending 
on the type of auxiliary tank) for continued use is a combination of 
actions. First, installing a transient suppression device (TSD) in the 
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 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.
    Furthermore, to reduce fuel vapor ignition risks associated with 
dry running of fuel pumps and fuel pump failures, operational 
limitations are needed to ensure that the fuel pumps

[[Page 78677]]

are turned off when the auxiliary tank is emptied. An inspection to 
detect fuel leakage in the dry bay and vent pipe shrouds needs to be 
included in the operator's maintenance program. Rogerson Aircraft 
Corporation has declared all STCs as high-flammability exposure 
installations, and has reported a few service difficulties with fuel 
leakage and damage to tank bladders during maintenance activities.
    Rogerson has not provided the service information required under 
SFAR 88 that would lead the FAA to make a finding of compliance; 
therefore, we must mandate the deactivation of all Rogerson Aircraft 
Corporation 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 and developing maintenance procedures to address the 
safety issues identified above.
    Once an operator has deactivated the tank as specified in this 
proposed 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.

Related Rulemaking

    AD 2008-12-03, amendment 39-15546 (73 FR 31749, June 4, 2008) 
applies to various transport category airplanes equipped with auxiliary 
fuel tanks installed in accordance with the identified Rogerson fuel 
tank STCs. That AD requires deactivation of Rogerson Aircraft 
Corporation auxiliary fuel tanks.
    We have determined that AD 2008-12-03 does not include STC 
SA3449NM, which is also subject to the identified unsafe condition, and 
might be installed on Boeing Model 727-281 airplanes.

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.
    This NPRM proposes the same requirements as AD 2008-12-03, but for 
airplanes that were not included in the applicability of that AD. In 
determining whether to supersede that AD or issue a new AD action, we 
considered the effect on the fleet of superseding AD 2008-12-03, and 
the consequent workload associated with revising maintenance record 
entries. In light of this, we have determined that a less burdensome 
approach is to issue a separate AD action for just the additional 
airplanes. This proposed AD would therefore not supersede AD 2008-12-
03. Airplanes listed in the applicability of AD 2008-12-03 must be in 
compliance with its requirements. This proposed AD is a separate AD 
action and applies only to Boeing Model 727-281 airplanes, certificated 
in any category and equipped with auxiliary fuel tanks installed in 
accordance with STC SA3449NM.

Costs of Compliance

    This proposed AD would affect about 17 U.S.-registered airplanes. 
The following table provides the estimated costs to comply with this 
proposed AD.

                                                 Estimated Costs
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                                     Work     Average labor                 Cost per
             Action                 hours     rate per hour     Parts       airplane           Fleet cost
----------------------------------------------------------------------------------------------------------------
Report..........................          1             $80         None          $80  $1,360.
Preparation of tank deactivation         80              80         None        6,400  Up to $108,800.
 procedure.
Physical tank deactivation......         30              80       $1,200        3,600  Up to $61,200.
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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:

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):

Boeing: Docket No. FAA-2008-1325; Directorate Identifier 2008-NM-
157-AD.

[[Page 78678]]

Comments Due Date

    (a) The FAA must receive comments on this AD action by February 
6, 2009.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 727-281 airplanes, 
certificated in any category and equipped with auxiliary fuel tanks 
installed in accordance with Supplemental Type Certificate (STC) 
SA3449NM.

Unsafe Condition

    (d) This AD results from fuel 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 60 days after the effective date of this AD, submit a 
report to the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA. Information collection requirements in this AD are 
approved by the Office of Management and Budget (OMB) under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.) 
and are assigned OMB Control Number 2120-0056. The report must 
include the following information:
    (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 for which the auxiliary tank is 
used.

Prevent Usage of Auxiliary Fuel Tanks

    (g) Within 90 days after the effective date of this AD, 
deactivate the auxiliary fuel tanks, in accordance with a 
deactivation procedure approved by the Manager of the Los Angeles 
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 might need 
to be included in the deactivation procedure. Timely approval is 
dependent on early submittal of the deactivation procedures.

    Note 2: For technical information, contact Dan Zevallos, 
Director of Program Management, Rogerson Aircraft Corporation, 2201 
Alton Parkway, Irvine, California 92606; phone (949) 442-2306; fax 
(949) 442-2322.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, ATTN: Serj Harutunian, Aerospace Engineer, Propulsion 
Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 
3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone 
(562) 627-5254; fax (562) 627-5210; 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.

Material Incorporated by Reference

    (i) None.

Appendix A

Deactivation Criteria

    The auxiliary fuel tank deactivation procedure required by 
paragraph (g) of this AD might need to 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.

    Note: If applicable, removing the bladder might help eliminate 
out-gassing.

    (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 Systems Installations. 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 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 14, 2008.
Michael J. Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-30518 Filed 12-22-08; 8:45 am]

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