Airworthiness Directives; McDonnell Douglas Model 717-200 Airplanes, 57892-57894 [E7-20049]
Download as PDF
<![CDATA[
57892
Federal Register / Vol. 72, No. 196 / Thursday, October 11, 2007 / Proposed Rules
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.
§ 39.13
[Amended]
mstockstill on PROD1PC66 with PROPOSALS
2. The Federal Aviation
Administration (FAA) amends § 39.13
by adding the following new
airworthiness directive (AD):
Boeing: Docket No. FAA–2007–0024;
Directorate Identifier 2007–NM–086–AD.
Comments Due Date
(a) The FAA must receive comments on
this AD action by November 26, 2007.
Affected ADs
(b) None.
VerDate Aug<31>2005
14:15 Oct 10, 2007
Jkt 214001
Applicability
(c) This AD applies to all Boeing Model
737–100, –200, –200C, –300, –400, and –500
series airplanes, certificated in any category.
Unsafe Condition
(d) This AD results from multiple reports
of cracks found in the skin, bearstrap, and/
or frame outer chord in the hinge cutout
areas of the forward entry and forward galley
service doorways. We are issuing this AD to
detect and correct such cracking, which
could result in rapid decompression 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.
Repetitive Inspections
(f) Except as provided by paragraph (g) of
this AD, at the applicable times specified in
paragraph 1.E. of Boeing Alert Service
Bulletin 737–53A1200, dated April 13, 2006,
do external detailed, low frequency eddy
current, high frequency eddy current, and
high frequency eddy current rotary probe
inspections, as applicable, for cracks in and
around the upper and lower hinge cutouts of
the forward entry and forward galley service
doorways, in accordance with the
Accomplishment Instructions of the service
bulletin, except as provided by paragraph (h)
of this AD. Do not exceed the applicable
repetitive interval for the previous
inspection, as specified in the service
bulletin as Option A or Option B. Repair any
crack before further flight using a method
approved in accordance with the procedures
specified in paragraph (i) of this AD.
Exceptions to Service Bulletin Specifications
(g) Where the service bulletin specifies a
compliance time after the release date of the
service bulletin, this AD requires compliance
within the specified compliance time after
the effective date of this AD.
(h) Although the service bulletin specifies
contacting Boeing for information about
installing an optional preventive
modification that would terminate the
repetitive inspections specified in this AD,
this AD requires that any terminating action
be done by using a method approved in
accordance with the procedures specified in
paragraph (i) of this AD.
Alternative Methods of Compliance
(AMOCs)
(i)(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.
(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.
(3) An AMOC that provides an acceptable
level of safety may be used for any repair
PO 00000
Frm 00004
Fmt 4702
Sfmt 4702
required by this AD, if it is approved by an
Authorized Representative for the Boeing
Commercial Airplanes Delegation Option
Authorization Organization who has been
authorized by the Manager, Seattle ACO, to
make those findings. For a repair method to
be approved, the repair must meet the
certification basis of the airplane, and the
approval must specifically refer to this AD.
Issued in Renton, Washington, on October
1, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E7–20048 Filed 10–10–07; 8:45 am]
BILLING CODE 4910–13–P
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
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
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.
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.
• Governmentwide rulemaking Web
site: Go to https://www.regulations.gov
and follow the instructions for sending
your comments electronically.
ADDRESSES:
E:\FR\FM\11OCP1.SGM
11OCP1
Federal Register / Vol. 72, No. 196 / Thursday, October 11, 2007 / Proposed Rules
• 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:
mstockstill on PROD1PC66 with PROPOSALS
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 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 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 https://
dms.dot.gov.
Examining the Docket
You may examine the AD docket on
the Internet at https://dms.dot.gov, or in
VerDate Aug<31>2005
14:15 Oct 10, 2007
Jkt 214001
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
PO 00000
Frm 00005
Fmt 4702
Sfmt 4702
57893
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.’’
E:\FR\FM\11OCP1.SGM
11OCP1
57894
Federal Register / Vol. 72, No. 196 / Thursday, October 11, 2007 / Proposed Rules
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.
mstockstill on PROD1PC66 with PROPOSALS
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
VerDate Aug<31>2005
14:15 Oct 10, 2007
Jkt 214001
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.
§ 39.13
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
[Amended]
2. The Federal Aviation
Administration (FAA) amends § 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.
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
Frm 00006
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2007–29330; Directorate
Identifier 2007–NM–199–AD]
RIN 2120–AA64
Airworthiness Directives; McDonnell
Douglas Model 717–200 Airplanes
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
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.
PO 00000
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.
Fmt 4702
Sfmt 4702
SUMMARY: The FAA proposes to adopt a
new airworthiness directive (AD) for
certain McDonnell Douglas Model 717–
200 airplanes. This proposed AD would
require electrical bonding of the fill
valves for the right and left main fuel
tanks, the fill valve and pipe assembly
E:\FR\FM\11OCP1.SGM
11OCP1
]]>Agencies
[Federal Register Volume 72, Number 196 (Thursday, October 11, 2007)]
[Proposed Rules]
[Pages 57892-57894]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-20049]
-----------------------------------------------------------------------
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).
-----------------------------------------------------------------------
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 https://dms.dot.gov and follow
the instructions for sending your comments electronically.
Governmentwide rulemaking Web site: Go to https://
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 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 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 https://dms.dot.gov.
Examining the Docket
You may examine the AD docket on the Internet at https://
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
