[Federal Register Volume 71, Number 54 (Tuesday, March 21, 2006)]
[Proposed Rules]
[Pages 14126-14129]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-4051]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24173; Directorate Identifier 2005-NM-262-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777 Airplanes

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 777 airplanes. This proposed AD would require 
a one-time inspection of the first bonding jumper aft of the bulkhead 
fitting to detect damage or failure and to determine the mechanical 
integrity of its electrical bonding path, and repair if necessary; 
measuring the bonding resistance between the fitting for the fuel feed 
tube and the front spar in the left and right main fuel tanks, and 
repairing the bonding if necessary; and applying additional sealant to 
completely cover the bulkhead fittings inside the fuel tanks. This 
proposed AD

[[Page 14127]]

results from fuel system reviews conducted by the manufacturer. We are 
proposing this AD to prevent arcing or sparking during a lightning 
strike at the interface between the bulkhead fittings of the engine 
fuel feed tube and the front spar inside the fuel tank. This arcing or 
sparking could provide a potential ignition source inside the fuel 
tank, 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 May 5, 2006.

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.
     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.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: John L. Vann, Aerospace Engineer, 
Propulsion Branch, ANM-140S, Seattle Aircraft Certification Office, 
FAA, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6513; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2006-
24173; Directorate Identifier 2005-NM-262-AD'' at the beginning 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 received 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 Web site, 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.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or 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 Docket Management System 
receives them.

Discussion

    We have 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)) 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.
    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.
    We have received a report indicating that, on certain Boeing Model 
747 airplanes, the sealant at the fitting for the fuel feed tube at the 
front spar bulkhead may be insufficient to protect against a spark 
between the bulkhead fitting and the spar in the event of a lightning 
strike. In SFAR 88-related testing, the manufacturer determined that a 
lightning strike can cause a spark even if the fitting is bonded. This 
condition, if not corrected, could result in a potential ignition 
source inside the fuel tank, which, in combination with flammable fuel 
vapors, could result in fuel tank explosions and consequent loss of the 
airplane.
    The affected area on certain Boeing Model 747 airplanes is similar 
in design to that on the affected Boeing Model 777 airplanes. 
Therefore, all of these models may be subject to the same unsafe 
condition.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 777-28-
0044, Revision 1, dated December 20, 2005. The service bulletin 
describes procedures for:
     Doing a general visual inspection of the first bonding 
jumper aft of the bulkhead fitting to detect damage or failure and to 
determine the mechanical integrity of its electrical bonding path.
     Measuring the bonding resistance between the fitting for 
the fuel feed tube and the front spar in the left main fuel tank, and 
repairing the bonding if it

[[Page 14128]]

exceeds certain limits defined in the service bulletin.
     Applying additional sealant to completely cover the 
bulkhead fitting inside the fuel tank.
    Accomplishing the actions specified in the service information is 
intended to 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. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between the Proposed AD and the Service Bulletin.''

Difference Between the Proposed AD and the Service Bulletin

    Although the service bulletin does not give repair instructions if 
any damage or failure is found during the general visual inspection, or 
if the mechanical integrity of the bonding path is compromised, this 
proposed AD would require doing the repair according to a method 
approved by the Manager, Seattle Aircraft Certification Office (ACO), 
FAA. Chapter 28-00-00 of the Boeing 777 Aircraft Maintenance Manual is 
one approved method.

Costs of Compliance

    There are about 497 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 131 airplanes of 
U.S. registry. The proposed actions would take about 8 work hours per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the proposed AD for U.S. operators is 
$83,840, or $640 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:
    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-2006-24173; Directorate Identifier 2005-NM-
262-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 5, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 777-200, -300, and -300ER 
series airplanes, certificated in any category; as identified in 
Boeing Special Attention Service Bulletin 777-28-0044, Revision 1, 
dated December 20, 2005.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent arcing or sparking 
during a lightning strike at the interface between the bulkhead 
fittings of the engine fuel feed tube and the front spar inside the 
fuel tank. This arcing or sparking could provide a potential 
ignition source inside the fuel tank, 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.

Inspection and Corrective Actions

    (f) Within 60 months after the effective date of this AD, do the 
actions in paragraphs (f)(1), (f)(2), and (f)(3) of this AD for the 
bulkhead fittings of the engine fuel feed tube for the left and 
right main fuel tanks. Do all actions in accordance with the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 777-28-0044, Revision 1, dated December 20, 2005.
    (1) Do a general visual inspection of the first bonding jumper 
aft of the bulkhead fitting to detect damage or failure and to 
determine the mechanical integrity of its electrical bonding path. 
If any damage or failure is found during this inspection or if the 
mechanical integrity of the bonding path is compromised: Before 
further flight, repair according to a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA. Chapter 
28-00-00 of the Boeing 777 Aircraft Maintenance Manual is one 
approved method.
    (2) Measure the bonding resistance between the fitting for the 
fuel feed tube and the front spar in the left main fuel tank. If the 
bonding resistance exceeds 0.001 ohm: Before further flight, repair 
the bonding in accordance with the service bulletin.
    (3) Apply additional sealant to completely cover the bulkhead 
fitting inside the fuel tank.

Actions Accomplished in Accordance With Previous Revision of Service 
Bulletin

    (g) Actions done before the effective date of this AD in 
accordance with Boeing Special Attention Service bulletin 777-28-
0044, dated February 3, 2005, are acceptable for compliance with the 
requirements of paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

[[Page 14129]]

    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

    Issued in Renton, Washington, on March 10, 2006.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-4051 Filed 3-20-06; 8:45 am]
BILLING CODE 4910-13-P