[Federal Register Volume 73, Number 153 (Thursday, August 7, 2008)]
[Proposed Rules]
[Pages 45895-45898]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-18222]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2008-0846; Directorate Identifier 2008-NM-045-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 757-200, 757-200PF, and
757-300 Series Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Boeing Model 757-200, 757-200PF, and 757-300 series airplanes.
This proposed AD would require, for certain airplanes, measuring the
electrical bond resistance at certain stations and doing any applicable
repair; installing support brackets for the hot short protector and new
support clamps for the wire bundles; installing the equipment of the
hot short protector; and modifying an existing wire bundle and
installing a new wire bundle. This proposed AD would also require, for
certain other airplanes, measuring the electrical bond resistance at
certain stations, measuring the electrical bonding resistance between
the hot short protector and rear spar web, and doing any applicable
repair. This proposed AD also would require revising the Airworthiness
Limitations section of the Instructions for Continued Airworthiness.
This proposed AD results from fuel system reviews conducted by the
manufacturer. We are proposing this AD to prevent the center fuel tank
densitometer from overheating and becoming a potential ignition source
inside the fuel tank, which, in combination with flammable fuel vapors,
could result in a center fuel tank explosion and consequent loss of the
airplane.
DATES: We must receive comments on this proposed AD by September 22,
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.
For service information identified in this AD, contact Boeing
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
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: Jen Pei, Aerospace Engineer, Systems
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone
(425) 917-6409; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
[[Page 45896]]
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-2008-0846;
Directorate Identifier 2008-NM-045-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)) 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 a 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.
Boeing has found that no separation was provided for the fuel
quantity indication system (FQIS) wires. A potential hot short of the
FQIS lead wire could cause the densitometer in the center fuel tank to
overheat. In situations where the fuel level in the center fuel tank is
low, the overheated densitometer could ignite flammable fuel vapors
inside the center fuel tank. This condition, if not corrected, could
result in a center fuel tank explosion and consequent loss of the
airplane.
Other Related Rulemaking
On April 29, 2008, we issued AD 2008-10-11, amendment 39-15517 (73
FR 25974, May 8, 2008), applicable to all Boeing Model 757 airplanes.
That AD requires revising the Airworthiness Limitations (AWLs) section
of the Instructions for Continued Airworthiness (ICA) by incorporating
new limitations for fuel tank systems to satisfy SFAR 88 requirements.
That AD also requires the initial inspection of certain repetitive AWL
inspections to phase in those inspections, and repair if necessary.
That AD resulted from a design review of the fuel tank systems. We
issued that AD to prevent the potential for ignition sources inside
fuel tanks caused by latent failures, alterations, repairs, or
maintenance actions, which, in combination with flammable fuel vapors,
could result in a fuel tank explosion and consequent loss of the
airplane. Incorporating AWL No. 28-AWL-22 into the AWLs section of the
ICA in accordance with paragraph (g)(3) of AD 2008-10-11 would
terminate the action in paragraph (h) of this proposed AD.
Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 757-28A0085,
Revision 2, dated December 11, 2007. The service bulletin describes the
following procedures:
For certain airplanes: Measuring the electrical bonding
resistance between the stiffeners located at inboard rear spar station
(IRSS) 164.9 and IRSS 179.2 and the rear spar web, and doing any
applicable repair; installing the support brackets of the hot short
protector (HSP) and the new support clamps of the wire bundles;
installing the equipment of the HSP; and modifying the existing wire
bundle and installing a new wire bundle (includes re-routing).
For certain other airplanes: Measuring the electrical
bonding resistance between the stiffeners located at IRSS 164.9 and
IRSS 179.2 and the rear spar web, measuring the electrical bonding
resistance between the HSP and the rear spar web, and doing any
applicable repair.
We have also reviewed section 9, Revision November 2007, of the
Boeing 757 Maintenance Planning Data (MPD) Document, D622N001-9
(hereafter referred to as ``the MPD''). Subsection G ``AIRWORTHINESS
LIMITATIONS--FUEL SYSTEM AWLs'' of the MPD describes AWLs for fuel tank
systems and includes AWL No. 28-AWL-22, which is the critical design
configuration control limitation to maintain the design features of the
center fuel tank's HSP during its replacement.
FAA's Determination and Requirements of This Proposed AD
We are proposing this AD because we evaluated all relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the(se) same type
design(s). This proposed AD would require accomplishing the actions
specified in the service information described previously.
Costs of Compliance
We estimate that this proposed AD would affect 433 airplanes of
U.S. registry. The following table provides the estimated costs for
U.S. operators to comply with this proposed AD.
[[Page 45897]]
Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average Number of
Work labor U.S.-
Action hours rate per Parts 1 Cost per product 1 registered Fleet cost 1
hour airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Groups 1-3; measurement, 8 $80 Between $14,110 and Between $14,750 and 433 Between $6,386,750 and
installations, and modification. $14,215. $14,855. $6,432,215.
Group 4; measurements................. 2 80 None..................... $160..................... 433 $69,280.
AWL Revision.......................... 1 80 None..................... $80...................... 433 $34,640.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Depending on airplane configuration.
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 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 this 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.
You can find our regulatory evaluation and the estimated costs of
compliance in the AD Docket.
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 AD:
Boeing: Docket No. FAA-2008-0846; Directorate Identifier 2008-NM-
045-AD.
Comments Due Date
(a) We must receive comments by September 22, 2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 757-200, 757-200PF, and 757-
300 series airplanes, certificated in any category; as identified in
Boeing Alert Service Bulletin 757-28A0085, Revision 2, dated
December 11, 2007.
Note 1:
This AD requires revisions to certain operator maintenance
documents to include new inspections. Compliance with these
inspections is required by 14 CFR 91.403(c). For airplanes that have
been previously modified, altered, or repaired in the areas
addressed by these inspections, the operator may not be able to
accomplish the inspections described in the revisions. In this
situation, to comply with 14 CFR 91.403(c), the operator must
request approval for an alternative method of compliance (AMOC)
according to paragraph (l) of this AD. The request should include a
description of changes to the required inspections that will ensure
the continued operational safety of the airplane.
Unsafe Condition
(d) This AD results from fuel system reviews conducted by the
manufacturer. We are issuing this AD to prevent the center fuel tank
densitometer from overheating and becoming a potential ignition
source inside the fuel tank, which, in combination with flammable
fuel vapors, could result in a center fuel tank explosion and
consequent loss of the airplane.
Compliance
(e) Comply with this AD within the compliance times specified,
unless already done.
Measurement, Installation, Modifications, Replacement, and Repair
(f) For Groups 1 through 3 airplanes, as identified in Boeing
Alert Service Bulletin 757-28A0085, Revision 2, dated December 11,
2007: Within 60 months after the effective date of this AD, do the
measurement, installations, modifications, replacement, and
applicable repair by accomplishing all the applicable actions
specified in the Accomplishment Instructions of the service
bulletin. Do the applicable repair before further flight.
Measure and Repair
(g) For Group 4 airplanes, as identified in Boeing Alert Service
Bulletin 757-28A0085, Revision 2, dated December 11, 2007: Within 60
months after the effective date of this AD, do the measurements and
applicable repair by accomplishing all the applicable actions
specified in the Accomplishment Instructions of the service
bulletin. Do the applicable repair before further flight.
Airworthiness Limitations (AWLs) Revision for AWL No. 28-AWL-22
(h) Concurrently with accomplishing the actions required by
paragraphs (f) and (g) of this AD, revise the AWLs section of the
Instructions for Continued Airworthiness (ICA) by incorporating AWL
No. 28-AWL-22 of Subsection G of section 9, Revision November 2007,
Boeing 757 Maintenance Planning Data (MPD) Document, D622N001-9.
No Alternative Critical Design Configuration Control Limitations
(CDCCLs)
(i) After accomplishing the action specified in paragraph (h) of
this AD, no alternative CDCCLs may be used unless the CDCCLs are
approved as an AMOC in accordance with the procedures specified in
paragraph (k) of this AD.
Credit for Actions Done According to Previous Issue of the Service
Bulletin
(j) Actions done before the effective date of this AD in
accordance with Boeing Alert Service Bulletin 757-28A0085, Revision
1, dated April 16, 2007, are acceptable for compliance with the
requirements of paragraphs (f) and (g) of this AD.
[[Page 45898]]
Terminating Action for AWLs Revision
(k) Incorporating AWL No. 28-AWL-22 into the AWLs section of the
ICA in accordance with paragraph (g)(3) of AD 2008-10-11, amendment
39-15517, terminates the action in paragraph (h) of this AD.
Alternative Methods of Compliance (AMOCs)
(l)(1) The Manager, Seattle ACO, FAA, ATTN: Jen Pei, Aerospace
Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle ACO,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone
(425) 917-6409; fax (425) 917-6590; 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.
Issued in Renton, Washington, on July 29, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-18222 Filed 8-6-08; 8:45 am]
BILLING CODE 4910-13-P