[Federal Register: October 11, 2007 (Volume 72, Number 196)]
[Proposed Rules]
[Page 57892-57894]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11oc07-20]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2007-29329; Directorate Identifier 2007-NM-205-AD]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model 717-200
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 McDonnell Douglas Model 717-200 airplanes. This proposed AD
would require modification of the conduit for the forward boost pump of
the center fuel tank. This proposed AD results from the finding that a
potential chafing condition exists in the volute assembly of the
forward boost pump for the center fuel tank. We are proposing this AD
to prevent chafing of the forward boost pump wiring that could lead to
arcing to the inside of the 45-degree angle fitting, which, in
combination with flammable fuel vapors, could result in a fuel tank
explosion and consequent loss of the airplane.
DATES: We must receive comments on this proposed AD by November 26,
2007.
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.
Governmentwide rulemaking Web site: Go to http://www.regulations.gov
and follow the instructions for sending your
comments electronically.
[[Page 57893]]
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.
Fax: (202) 493-2251.
Hand Delivery: Room W12-140 on the ground floor of the
West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
Contact Boeing Commercial Airplanes, Long Beach Division, 3855
Lakewood Boulevard, Long Beach, California 90846, Attention: Data and
Service Management, Dept. C1-L5A (D800-0024), for the service
information identified in this proposed AD.
FOR FURTHER INFORMATION CONTACT: Samuel S. Lee, Aerospace Engineer,
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137;
telephone (562) 627-5262; fax (562) 627-5210.
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-2007-
29329; Directorate Identifier 2007-NM-205-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 Operations office between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The
Docket Operations office (telephone (800) 647-5527) is located on the
ground level of the West 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
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 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.
We have received a report indicating that a potential chafing
condition exists in the volute assembly of the forward boost pump for
the center fuel tank, on McDonnell Douglas Model 717-200 airplanes.
Boeing discovered this condition during an investigation of the wiring
installations for the fuel boost pump. The wiring that provides
electrical power to the forward boost pump for the center fuel tank is
installed in a flexible conduit inside the right wing fuel tank and is
routed to the volute assembly. The potential chafing area exists at the
45-degree angle fitting (made of anodized aluminum) of the volute
assembly. This angle fitting has been found to have an internal
uncontrolled edge that could cause damage to the wiring insulation.
Chafed wiring could lead to arcing to the inside of the 45-degree angle
fitting. This condition, if not corrected, in combination with
flammable fuel vapors, could result in a fuel tank explosion and
consequent loss of the airplane.
Relevant Service Information
We have reviewed Boeing Service Bulletin 717-28-0007, Revision 1,
dated September 23, 2003. The service bulletin describes procedures for
modifying the conduit for the forward boost pump of the center fuel
tank. The modification includes removing conduit from the 45-degree
angle fitting of the forward boost pump and routing the conduit to the
existing straight fitting in the bottom of the pump volute located in
the right wing 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 Service Bulletin.''
[[Page 57894]]
Difference Between the Proposed AD and Service Bulletin
Although the service bulletin recommends accomplishing the
modification at ``a scheduled maintenance period when manpower,
materials, and facilities are available,'' we have determined that this
compliance time is imprecise and would not address the identified
unsafe condition in a timely manner. In developing an appropriate
compliance time for this AD, we considered not only the manufacturer's
recommendation, but 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 modification. In light of
all of these factors, we find a compliance time of 78 months for
completing the required actions to be warranted, in that it represents
an appropriate interval of time for affected airplanes to continue to
operate without compromising safety. We have coordinated this
difference with Boeing.
Costs of Compliance
There are about 77 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 61 airplanes of
U.S. registry. The proposed actions would take about 9 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
$43,920, or $720 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):
McDonnell Douglas: Docket No. FAA-2007-29329; Directorate Identifier
2007-NM-205-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by November
26, 2007.
Affected ADs
(b) None.
Applicability
(c) This AD applies to McDonnell Douglas Model 717-200
airplanes, certificated in any category; as identified in Boeing
Service Bulletin 717-28-0007, Revision 1, dated September 23, 2003.
Unsafe Condition
(d) This AD results from a finding that a potential chafing
condition exists in the volute assembly of the forward boost pump
for the center fuel tank. We are issuing this AD to prevent chafing
of the forward boost pump wiring that could lead to arcing to the
inside of the 45-degree angle fitting, which, in combination with
flammable fuel vapors, could result in a fuel tank explosion 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.
Modification
(f) Within 78 months after the effective date of this AD, modify
the conduit for the forward boost pump of the center fuel tank, by
accomplishing all of the actions specified in the Accomplishment
Instructions of Boeing Service Bulletin 717-28-0007, Revision 1,
dated September 23, 2003.
Alternative Methods of Compliance (AMOCs)
(g)(1) The Manager, Los Angeles 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.
(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 October 1, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-20049 Filed 10-10-07; 8:45 am]
BILLING CODE 4910-13-P