Airworthiness Directives; Boeing Model 757 Airplanes, 14594-14597 [05-5698]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 55 (Wednesday, March 23, 2005)]
[Proposed Rules]
[Pages 14594-14597]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-5698]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20689; Directorate Identifier 2004-NM-197-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 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 757-200, -200PF, -200CB, and -300 series 
airplanes. This proposed AD would require, for certain airplanes, 
reworking the spar bonding path and reapplying sealant; and, for 
certain other airplanes, testing the electrical bond between the engine 
fuel feed hose and the wing front spar and, if applicable, reworking 
the spar bonding path and reapplying sealant. This proposed AD would 
also require, for all airplanes, an inspection to ensure the electrical 
bonding jumper is installed between the engine fuel feed hose and the 
adjacent wing station. This proposed AD is prompted by the results of 
fuel system reviews conducted by the manufacturer. 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 
during a lightning strike, which could provide a possible ignition 
source for the fuel vapor inside the fuel tank and result in a fuel 
tank explosion.

DATES: We must receive comments on this proposed AD by May 9, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to https://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to https://
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.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    You can examine the contents of this AD docket on the Internet at 
https://dms.dot.gov, or in person 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. This docket 
number is FAA-2005-20689; the directorate identifier for this docket is 
2004-NM-197-AD.

FOR FURTHER INFORMATION CONTACT: Tom Thorson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6508; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments

[[Page 14595]]

regarding this proposed AD. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2005-20689; Directorate 
Identifier 2004-NM-197-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 https://
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 can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit https://dms.dot.gov.

Examining the Docket

    You can examine the AD docket on the Internet at https://
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 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.
    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.
    In addition, we have received a report indicating that, during 
electrical bonding and grounding tests of Boeing Model 747 series 
airplane wing fuel tank penetrations, the bulkhead fittings of the 
engine fuel feed tube were found not to be electrically bonded to the 
front spar. The same condition is found on certain Model 707 series 
airplanes; on all Model 737-100, -200, -300, -400, and -500 series 
airplanes; on all Model 747 series airplanes; and on certain Model 757 
and Model 767 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. This condition could also exist on certain Model 757 
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 front spar during a lightning strike, which could provide a 
possible ignition source for the fuel vapor inside the fuel tank and 
result in a fuel tank explosion.

Related Rulemaking

    On November 10, 2004, we issued notice of proposed rulemaking 
(NPRM) Docket No. FAA-2004-19680 (Directorate Identifier 2003-NM-215-
AD), which is applicable to certain Boeing Model 767 series airplanes. 
That NPRM would require performing a test of the bonding resistance 
between the engine fuel feed tube fitting and the front spar, applying 
sealant on a hex nut inside the dry bay, and performing any applicable 
corrective actions. The actions specified by that NPRM are intended to 
prevent an ignition source from entering the fuel tank during a 
lightning strike event, which could cause a fuel tank explosion.
    On July 15, 2004, we issued NPRM Docket No. FAA-2004-18759 
(Directorate Identifier 2003-NM-280-AD), which is applicable to certain 
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. That NPRM 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 engine 
fuel feed tube and the front spar inside the fuel tank of the wings; 
other specified actions; and applicable corrective actions if 
necessary. The actions specified by that NPRM are intended 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.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletins 757-28A0076 (for 
Model 757-200, -200CB, and -200PF series airplanes); and 757-28A0077 
(for Model 757-300 series airplanes); both dated August 27, 2004. The 
service bulletins describe procedures for testing

[[Page 14596]]

the electrical bond between the engine fuel feed hose and the wing 
front spar; reworking the bonding path between the end fitting of the 
fuel hose and the front spar; adding sealant to hose fittings and tube 
couplings, as applicable; and performing a general visual inspection 
and applicable corrective actions to ensure that an electrical bonding 
jumper is installed between the engine fuel feed hose and the adjacent 
wing station 285.65 rib in the left and right wing fuel tanks.
    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. Therefore, 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 Referenced Service 
Bulletins.''

Difference Between the Proposed AD and Referenced Service Bulletins

    Although the referenced service bulletins would allow operator's 
equivalent procedures to be used for aircraft maintenance manuals (AMM) 
referenced in the service bulletins, this proposed AD would require you 
to use the referenced AMMs except as provided in paragraph (j) of this 
proposed AD.

Costs of Compliance

    There are about 1,040 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 700 airplanes of 
U.S. registry. The average labor rate is estimated to be $65 per work 
hour. Parts would be supplied from operator stock. The following table 
provides the estimated costs for U.S. operators to comply with this 
proposed AD.

                             Estimated Costs
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                                                               Cost per
           Action/airplanes affected            Work  hours    airplane
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Hose fitting and spar bonding rework and                 11         $715
 sealant application (Group 1 airplanes)......
Bonding test and sealant application (Group 2             9          585
 airplanes that pass bonding test)............
Bonding test, hose fitting and spar bonding              13          845
 rework and sealant application (Group 2
 airplanes that fail bonding test)............
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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. 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-2005-20689; Directorate Identifier 2004-NM-
197-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by May 9, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 757-200, -200PF, and -200CB, 
series airplanes as listed in Boeing Alert Service Bulletin 757-
28A0076, dated August 27, 2004; and Model 757-300 series airplanes 
as listed in Boeing Alert Service Bulletin 757-28A0077, dated August 
27, 2004; certificated in any category.

Unsafe Condition

    (d) This AD was prompted by the results of fuel system reviews 
conducted by the manufacturer. 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 during a lightning 
strike, which could provide a possible ignition source for the fuel 
vapor inside the fuel tank and result in a fuel tank explosion.

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 Bulletin References

    (f) The term ``service bulletin(s),'' as used in this AD, means 
the Accomplishment Instructions of the following service bulletins, 
as applicable.
    (1) For Model 757-200, -200CB, and -200PF series airplanes: 
Boeing Alert Service Bulletin 757-28A0076, dated August 27, 2004.

[[Page 14597]]

    (2) For Model 757-300 series airplanes: Boeing Alert Service 
Bulletin 757-28A0077, dated August 27, 2004.

Hose Fitting and Spar Bonding Rework and Sealant Application

    (g) For Group 1 airplanes as identified in the service 
bulletins: Within 48 months after the effective date of this AD, 
rework the spar bonding path between the end fitting of the fuel 
feed hose and the front spar, and apply sealant to the hose fitting 
on the forward and aft side of the front spar and to the fitting and 
tube coupling on both sides of the dry bay wall, in accordance with 
the service bulletins.

Bonding Resistance Test

    (h) For Group 2 airplanes as identified in the service 
bulletins: Within 48 months after the effective date of this AD, do 
a bonding resistance test between the fuel feed hose and the front 
spars of the left and right wings, in accordance with the service 
bulletins.
    (1) If the test meets required resistance limits, before further 
flight, apply sealant to the end fitting of the fuel feed hose on 
the aft side of the front spar and to the fitting and tube coupling 
on both sides of the dry bay wall, in accordance with the service 
bulletins.
    (2) If the test does not meet required resistance limits, before 
further flight, remove any existing sealant at the front spar; 
rework the spar bonding path between the end fitting of the fuel 
feed hose and the front spar to meet bonding resistance test 
requirements; and apply sealant to the end fitting of the fuel feed 
hose on the forward and aft sides of the front spar, and to the 
fitting and tube coupling on both sides of the dry bay wall, in 
accordance with the service bulletins.

Inspection of Electrical Bonding Jumper

    (i) For all airplanes as identified in the service bulletins: 
Within 48 months after the effective date of this AD, perform a 
general visual inspection and applicable corrective actions to 
ensure that an electrical bonding jumper is installed between the 
engine fuel feed hose and the adjacent wing station 285.65 rib in 
the left and right wing fuel tanks, in accordance with the service 
bulletins.

Exception to Accomplishment Instructions in Service Bulletins

    (j) Although Boeing Alert Service Bulletin 757-28A0076, and 
Boeing Alert Service Bulletin 757-28A0077, both dated August 27, 
2004, permit operator's equivalent procedures (OEP), this AD would 
require you to use the referenced AMMs, except that operators may 
use their own FAA-approved OEPs to drain the left and right engine 
fuel tubes, to drain and ventilate the fuel tanks, and for entering 
the fuel tanks.

Alternative Methods of Compliance (AMOCs)

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

    Issued in Renton, Washington, on March 14, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-5698 Filed 3-22-05; 8:45 am]
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