[Federal Register Volume 69, Number 149 (Wednesday, August 4, 2004)]
[Proposed Rules]
[Pages 47031-47035]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17763]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-18759; Directorate Identifier 2003-NM-280-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 707-100, -100B, -300, -
300B (-320B Variant), -300C, and -E3A (Military) Series Airplanes; 
Model 720 and 720B Series Airplanes; Model 737-100, -200, -200C, -300, 
-400, and -500 Series Airplanes; and Model 747 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing transport category airplanes. This proposed AD would 
require repetitive tests of the overwing fuel fill ports for certain 
wing tanks; an electrical bonding resistance test between the bulkhead 
fittings of the

[[Page 47032]]

engine fuel feed tube and the front spar inside the fuel tank of the 
wings; other specified actions; and applicable corrective actions if 
necessary. This proposed AD is prompted by our determination that this 
AD is necessary to reduce the potential for ignition sources inside 
fuel tanks. We are proposing this AD to prevent arcing or sparking at 
the interface between the bulkhead fittings of the engine fuel feed 
tube and the front spar inside the fuel tank of the wings and between 
the overwing fuel fill ports and the airplane structure during a 
lightning strike. Such arcing or sparking could provide a possible 
ignition source for the fuel vapor inside the fuel tank and cause 
consequent fuel tank explosions.

DATES: We must receive comments on this proposed AD by September 20, 
2004.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     By fax: (202) 493-2251.
     Hand Delivery: room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. 
and 5 p.m., Monday through Friday, except Federal holidays.
    You can get the service information identified in this proposed AD 
from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    You may examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street SW., room PL-401, on 
the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6501; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

    The FAA has implemented new procedures for maintaining AD dockets 
electronically. As of May 17, 2004, new AD actions are posted on DMS 
and assigned a docket number. We track each action and assign a 
corresponding directorate identifier. The DMS AD docket number is in 
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane 
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier 
(``Old Docket Number'') as a cross-reference for searching purposes.

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-18759; 
Directorate Identifier 2003-NM-280-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that website, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.
    We are reviewing the writing style we currently use in regulatory 
documents. We are interested in your comments on whether the style of 
this document is clear, and your suggestions to improve the clarity of 
our communications that affect you. You can get more information about 
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

    You may examine the AD docket in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the DOT street address stated in the ADDRESSES section. 
Comments will be available in the AD docket shortly after the DMS 
receives them.

Discussion

    We have examined the underlying safety issues involved in recent 
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)) 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, 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.
    Based on this process, 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

[[Page 47033]]

in fuel tank explosions and consequent loss of the airplane.
    In addition, we have received a report indicating that, during an 
electrical bonding and grounding test of 747 wing fuel tank 
penetrations, the bulkhead fittings of the engine fuel feed tube were 
not electrically bonded to the front spar. The same condition is found 
on some Model 707 series airplanes; on all Model 737-100, -200, -300, -
400, and -500 series airplanes; and on all Model 747 series airplanes. 
We also received a report indicating that a lightning test showed a 
higher-than-expected electrical current in the engine fuel feed tubes 
inside the wing fuel tank on Model 747 series airplanes.
    If the bulkhead fittings of the engine fuel feed tubes are not 
electrically bonded, there is a potential for arcing or sparking at the 
interface between the bulkhead fittings of the engine fuel feed tube 
and the wing front spar during a lightning strike. This event, in turn, 
could provide a possible ignition source for the fuel vapor inside the 
fuel tank and result in fuel tank explosions.
    We also received a report that an inspection of the overwing fuel 
fill port showed that the overwing filler adapter may not be bonded to 
the upper wing skin on Model 707 and 720 series airplanes. The improper 
bonding has been attributed to incorrect installation or missing 
electrical bond data in the airplane maintenance manual or installation 
drawings. Also, an inspection done for SFAR 88 revealed that overwing 
fuel fill ports for wing tanks No. 1 and No. 4 and the center wing tank 
on Boeing Model 707 and 720 series airplanes can be lightning ignition 
sources because of their location. The overwing fuel fill ports for 
wing tanks No. 1 and No. 4 are located in an area where lightning, 
after initially attaching to the engine cowls or nose of the airplane, 
remains attached to the airplane and sweeps back as the airplane moves 
forward through the lightning channel. This creates a series of 
attachment points behind the initial attachment point. The overwing 
fuel fill ports are located either behind the engine nacelles or behind 
the nose of the airplane and are subject to these subsequent lightning 
attachments.
    If the overwing fuel fill ports for wing tanks No. 1 and No. 4 and 
the center wing tank are not electrically bonded correctly, there is a 
potential for arcing or sparking at the interface between the ports and 
the airplane structure during a lightning strike. This event, in turn, 
could provide a possible ignition source for the fuel vapor inside the 
fuel tank and cause consequent fuel tank explosions.

Relevant Service Information

    We have reviewed and approved the following service bulletins:

                      Referenced Service Bulletins
------------------------------------------------------------------------
               For model                              Boeing
------------------------------------------------------------------------
707-E3A (military), -100, -100B, -300, - Alert Service Bulletin A3505,
 300B (-320B variant), and -300C series   dated November 1, 2001.
 airplanes; and 720 series airplanes.
707-100, -100B, -300, -300B, and -300C   Service Bulletin 3513, dated
 series airplanes; and 720 and 720B       November 6, 2003.
 series airplanes.
737-100, -200, -200C, -300, -400, and -  Service Bulletin 737-28A1174,
 500 series airplanes.                    Revision 1, dated July 18,
                                          2002.
747-100, -100B, -100B SUD, -200B, -      Alert Service Bulletin 747-
 200C, -200F, -300, -400, -400D, and -    28A2239, Revision 1, dated
 400F series airplanes; and 747SP and     October 17, 2002.
 747SR series airplanes.
747-400 and -400F series airplanes.....  Alert Service Bulletin 747-
                                          28A2245, Revision 1, dated
                                          August 21, 2003.
------------------------------------------------------------------------

    Boeing Service Bulletin 3513 describes procedures for repetitive 
electrical bonding resistance tests of the overwing fuel fill ports for 
wing tanks No. 1 and No. 4 and the center wing tank, and applicable 
corrective actions. The applicable corrective actions include:
     Cleaning certain surfaces;
     Applying certain sealants, chemical film coating, and an 
aero smoother;
     Installing the filler adapter and electrically bonding it; 
and
     Testing the fuel feed system for leaks.
    The remaining service bulletins describe procedures for an 
electrical bonding resistance test between the bulkhead fittings of the 
engine fuel feed tube and the front spar inside the fuel tank of the 
wings, other specified actions, and applicable corrective actions. The 
other specified actions include the following:
     Draining the fuel tanks;
     Removing the fuel feed tubes, fuel manifold, and the 
bulkhead fittings; and
     Cleaning the fittings and front spar areas.
    The applicable corrective actions include:
     Cleaning certain surfaces;
     Applying certain sealants;
     Installing certain parts; and
     Testing the fuel feed system for leaks.
    We have determined that accomplishment of the actions specified in 
the applicable service bulletin will adequately address the unsafe 
condition.

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 airplanes 
of this same type design. Therefore, we are proposing this AD, which 
would require, for certain airplanes, repetitive electrical bonding 
resistance tests of the overwing fuel fill ports for wing tanks No. 1 
and No. 4 and the center wing tank, and applicable corrective actions. 
The proposed AD also would require, for certain other airplanes, an 
electrical bonding resistance test between the bulkhead fittings of the 
engine fuel feed tube and the front spar inside the fuel tank of the 
wings, other specified actions, and applicable corrective actions. The 
proposed AD would require using the service information described 
previously to perform these actions, except as discussed under 
``Difference Between the Proposed AD and the Service Bulletins.''

Difference Between the Proposed AD and Certain Service Bulletins

    Although certain service bulletins recommend accomplishing the 
electrical bonding resistance test ``at the earliest opportunity where 
manpower, materials and facilities are available,'' we have determined 
that this imprecise compliance time would not address the identified 
unsafe condition in a timely manner. In developing an appropriate 
compliance time for this proposed AD, we considered not only the 
manufacturer's recommendation, but

[[Page 47034]]

the degree of urgency associated with addressing the subject unsafe 
condition, the average utilization of the affected fleet, and the time 
necessary to perform the test. In light of all of these factors, we 
find a compliance time of 5 years for completing the proposed actions 
to be warranted, in that it represents an appropriate interval of time 
for affected airplanes to continue to operate without compromising 
safety.

Costs of Compliance

    This proposed AD would affect about 4,303 series airplanes 
worldwide. The following table provides the estimated costs for U.S. 
operators to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Number of
                                                                     Average                                   U.S.-
              For model                        Work hours          labor rate       Cost per airplane       registered              Fleet cost
                                                                    per hour                                 airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
707-E3A (military), -100, -100B, -     16.......................           $65  $1,040...................            41  $42,640
 300, -300B (including -320B
 variant), and -300C series
 airplanes; and 720 series airplanes.
707-100, -100B, -300, -300B, and -     Between 4 and 6..........            65  Between 260 and 390......            73  Between 18,980 and 28,470
 300C series airplanes; and 720 and
 720B series airplanes.
737-100, -200, -200C, -300, -400, and  8........................            65  520......................         1,095  569,400
 -500 series airplanes.
747-100, -100B, -100B SUD, -200B, -    70.......................            65  4,550....................           257  1,169,350
 200C, -200F, -300, -400, -400D, and -
 400F series airplanes; and 747SP and
 747SR series airplanes.
747-400 and -400F series airplanes...  18.......................            65  1,170....................             1  1,170
--------------------------------------------------------------------------------------------------------------------------------------------------------

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

Boeing: Docket No. FAA-2004-18759; Directorate Identifier 2003-NM-
280-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by September 20, 2004.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the airplanes listed in Table 1 of this 
AD, certificated in any category.

                         Table 1.--Applicability
------------------------------------------------------------------------
                 Model                             As listed in
------------------------------------------------------------------------
707-E3A (military), -100, -100B, -300, - Boeing Alert Service Bulletin
 300B.                                    A3505, dated November 1, 2001.
(-320B variant), and -300C series
 airplanes; and 720 series airplanes.
707-100, -100B, -300, -300B, and -300C   Boeing Service Bulletin 3513,
 series airplanes; and 720 and 720B       dated November 6, 2003.
 series airplanes.
737-100, -200, -200C, -300, -400, and -  Boeing Service Bulletin 737-
 500 series airplanes.                    28A1174, Revision 1, dated
                                          July 18, 2002.
747-100, -100B, -100B SUD, -200B, -      Boeing Alert Service Bulletin
 200C, -200F, -300, 400, -400D, and -     747-28A2239, Revision 1, dated
 400F series airplanes; and 747SP and     October 17, 2002.
 747SR series airplanes.
747-400 and -400F series airplanes.....  Boeing Alert Service Bulletin
                                          747-28A2245, Revision 1, dated
                                          August 21, 2003.
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD was prompted by our determination that this AD is 
necessary to reduce the potential for ignition sources inside fuel 
tanks. We are issuing this AD to prevent arcing or sparking at the 
interface between the bulkhead fittings of the engine fuel feed tube 
and the front spar of the wings and between the overwing fuel fill 
ports and the airplane structure during a lightning strike. Such 
arcing or sparking could provide a possible ignition source for the 
fuel vapor inside the fuel tank and cause consequent fuel tank 
explosions.

[[Page 47035]]

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.

Service Bulletins

    (f) The term ``service bulletin,'' as used in this AD, means the 
Work Instructions of the applicable service bulletins specified in 
the ``As Listed In'' column of Table 1 of this AD.
    (g) Actions specified in paragraphs (h) through (i) of this AD 
that were done before the effective date of this AD in accordance 
with the applicable service information listed in Table 2 of this AD 
are acceptable for compliance with the applicable requirements of 
this AD.

        Table 2.--Acceptable Original Issues of Service Bulletins
------------------------------------------------------------------------
               For model                              Boeing
------------------------------------------------------------------------
(1) 737-100, -200, -200C, -300, -400,    Service Bulletin 737-28A1174,
 and -500 series airplanes.               dated December 20, 2001.
(2) 747-100, -100B, -100B SUD, -200B, -  Alert Service Bulletin 747-
 200C, -200F, -300, -400, -400D, and -    28A2239, dated November 29,
 400F series airplanes; and 747SP and     2001.
 747SR series airplanes.
(3) 747-400 and -400F series airplanes.  Alert Service Bulletin 747-
                                          28A2245, dated November 26,
                                          2002.
------------------------------------------------------------------------

Resistance Test, Other Specified Actions, and Corrective Actions

    (h) For the airplanes identified in paragraphs (h)(1) through 
(h)(4) of this AD: Within 5 years after the effective date of this 
AD, do an electrical bonding resistance test between the bulkhead 
fittings of the engine fuel feed tube and the front spar inside the 
fuel tank of the wings to determine the resistance, and do other 
specified actions and applicable corrective actions, by 
accomplishing all the actions specified in paragraph 3.B. of the 
applicable service bulletin. Do the actions in accordance with the 
service bulletin. Do the applicable corrective actions before 
further flight.
    (1) Model 707-E3A (military), -100, -100B, -300, -300B (-320B 
variant), and -300C series airplanes; and Model 720 series 
airplanes.
    (2) Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes.
    (3) Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, 
-400, -400D, and -400F series airplanes; and Model 747SP and 747SR 
series airplanes.
    (4) Model 747-400 and -400F series airplanes.
    (i) For Model 707-100, -100B, -300, -300B, and -300C series 
airplanes; and Model 720 and 720B series airplanes: Within 5 years 
after the effective date of this AD, do an electrical bonding 
resistance test of the over-wing fuel fill ports for the wing tanks 
No. 1 and No. 4 and the center wing tank to determine the 
resistance, and do applicable corrective actions, by accomplishing 
all the actions specified in paragraph 3.B. of the applicable 
service bulletin. Do the actions in accordance with the service 
bulletin. Do the applicable corrective actions before further 
flight. Repeat the electrical bonding resistance test at intervals 
not to exceed 14,000 flight hours.

Alternative Methods of Compliance (AMOCs)

    (j) 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.

    Issued in Renton, Washington, on July 15, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-17763 Filed 8-3-04; 8:45 am]
BILLING CODE 4910-13-P