[Federal Register Volume 62, Number 2 (Friday, January 3, 1997)]
[Rules and Regulations]
[Pages 304-307]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-33105]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-277-AD; Amendment 39-9870; AD 96-26-06]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Boeing Model 747 series airplanes. This action
requires a one-time inspection to detect damage of the sleeving and
wire bundles of the boost pumps of the numbers 1 and 4 main fuel tanks,
and of the auxiliary tank jettison pumps (if installed); replacement of
any damaged sleeving with new sleeving; and repair or replacement of
any damaged wires with new wires. For airplanes on which any burned
wires are found, this action also requires an inspection to detect
damage of the conduit, and replacement of any damaged conduit with a
serviceable conduit. This amendment is prompted by an FAA determination
that an environment conducive to vibration exists in the conduit and
wire bundles of the boost pumps and of the auxiliary tank jettison
pumps, which can cause abrasion of the Teflon sleeving and subsequent
abrasion of the wires in the bundles. The actions specified in this AD
are intended to detect and correct such abrasion, which could result in
electrical arcing between the wires and the aluminum conduit and
subsequent fire or explosion of the fuel tank.
DATES: Effective January 21, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 21, 1997.
Comments for inclusion in the Rules Docket must be received on or
before March 4, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-277-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from
Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington
98124-2207. This information may be examined at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at
the Office of the Federal Register, 800 North Capitol Street, NW.,
suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: G. Michael Collins, Aerospace
Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (206) 227-2689; fax (206)
227-1181.
SUPPLEMENTARY INFORMATION: On July 17, 1996, a Boeing Model 747 series
airplane broke up during climb over the Atlantic Ocean after takeoff
from John F. Kennedy International Airport, Jamaica, New York. Although
the National Transportation Safety Board (NTSB) has not determined the
cause of the accident, it has identified mechanical failure as one
possible cause. The NTSB also stated that the center fuel tank exploded
at some time during the accident. However, the NTSB has not determined
if that explosion was the cause of the accident or the result of some
other event. Following the accident, the FAA began investigating
potential failures that could result in ignition sources in the fuel
tanks installed on Model 747 series airplanes.
Other Relevant Rulemaking and Survey
As part of its investigation, the FAA reviewed the actions required
by certain existing AD's, and the results of a survey conducted on in-
service Model 747 series airplanes, as discussed below.
In 1979, the FAA issued AD 79-05-04, amendment 39-3431 (44 FR
12636, March 8, 1979). That AD was prompted by a report indicating that
the fuel pump wires in an aluminum conduit in an auxiliary fuel tank on
a Model 747 series airplane chafed through the insulation. Electrical
arcing from the chafed wire to the aluminum conduit caused a hole in
the conduit; however, the arcing did not cause a fire or explosion. The
hole in the conduit was discovered because fuel leaked through the hole
and out of the conduit at the rear spar.
AD 79-05-04 required discontinuing the use of the auxiliary fuel
tanks, draining fuel from those tanks, and opening and collaring the
circuit breakers for the auxiliary tank jettison pumps. Those actions
were required to be accomplished prior to further flight. The actions
required by that AD affected 10 Model 747-200 series airplanes, unless
Teflon sleeving had been installed on the wire bundles in accordance
with Boeing Alert Service Bulletin 747-28A2091, Revision 1, dated
February 5, 1979, or unless the pumps had been deactivated previously
in accordance with Boeing Service
[[Page 305]]
Bulletin 747-28-2067, dated November 11, 1977. The FAA has been advised
that use of the fuel tanks has been discontinued on eight of the
affected airplanes, and that Teflon sleeving has been installed on the
wire bundles of two of the affected airplanes.
Following the issuance of AD 79-05-04, a survey involving an
inspection of the wires in the conduits for the numbers 1 and 4 fuel
tank pumps was conducted on approximately 26 in-service Model 747
series airplanes. The results of that survey revealed that numerous
wires in these conduits were chafing against the conduit. Although none
of the wires inspected at that time had worn completely through the
insulation, chafing through up to 80 percent of the total insulation
thickness was found on numerous wires.
Based on these survey results, the FAA issued AD 79-06-02,
amendment 39-3439 (44 FR 16362, March 19, 1979). That AD requires an
inspection, repair, and modification of the outboard main fuel tanks
(numbers 1 and 4) boost pump wires in the conduits located in the
inboard main fuel tanks (numbers 2 and 3) on Model 747 series
airplanes. Any chafed wires are required to be replaced, and Teflon
sleeving is to be installed to prevent chafing or abrasion of the wires
against the conduit. Those actions were required to be accomplished
within 750 hours time-in-service or 2 months, whichever occurred first,
after the airplane had accumulated either 6,000 or 30,000 total hours
time-in-service, depending upon the type of wires installed. The
modification required by AD 79-06-02 involves tying the wires together
every six inches and installing two concentric Teflon sleeves over the
wire bundle. The requirements of that AD were intended to prevent
abrasion of the electrical wires of the fuel tank boost pumps.
Background Information
The numbers 1 and 4 main fuel tanks (outboard main tanks) on Model
747 series airplanes each have two boost pumps that are located in dry
bays (``dog houses'') inside the numbers 2 and 3 main fuel tanks
(inboard main tanks). The electrical power for these boost pumps is
supplied by wiring routed through aluminum conduits inside the inboard
main tanks. These conduits begin at the wing rear spar and end at the
boost pump dog houses. The wires are separated from the conduit by two
concentric Teflon sleeves that are installed over the wire bundles.
The auxiliary tank jettison pumps, if installed, are located in the
auxiliary fuel tanks. These pumps are mounted in dog houses inside the
auxiliary fuel tanks. The electrical power for these pumps is routed
through aluminum conduit inside the auxiliary fuel tanks, similar to
the conduit of the boost pumps for the numbers 1 and 4 main fuel tanks.
Vibration of the conduit and wire bundles can cause abrasion of the
Teflon sleeving, which could lead to abrasion of the wires in the
bundles. Such abrasion, if not corrected, could result in electrical
arcing between the wires and the aluminum conduit and subsequent fire
or explosion of the fuel tank.
FAA's Determinations
The FAA finds that an environment conducive to vibration still
exists in the conduit and wire bundles of the fuel boost pumps and the
auxiliary tank jettison pumps (if installed). The FAA has determined
that wire chafing has occurred on Model 747 series airplanes inside
other conduits located outside the main fuel tanks in the vicinity of
the conduits addressed in AD 79-06-02. In some cases, chafing through
both the Teflon sleeving and the wire insulation has occurred on these
airplanes [reference AD 96-03-14, amendment 39-9511 (61 FR 6500,
February 21, 1996), and AD 89-14-04, amendment 39-6246 (54 FR 27157,
June 28, 1989)]. The FAA concludes that follow-on inspections of the
Teflon sleeving must be accomplished to determine if the sleeving
continues to provide a protective barrier after extended time in
service.
Explanation of Relevant Service Information
The FAA reviewed and approved Boeing Alert Service Bulletin 747-
28A2204, dated December 19, 1996, which describes procedures for a one-
time inspection to detect damage of the sleeving and wire bundles of
the forward and aft boost pumps of the numbers 1 and 4 main fuel tanks,
and of the wire bundles of the auxiliary tank jettison pumps (if
installed); and repair or replacement of damaged parts with new parts.
For airplanes on which any burned wires are found, the alert service
bulletin describes procedures for an inspection to detect damage of the
conduit, and replacement of any damaged conduit with a serviceable
conduit.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other Boeing Model 747 series airplanes of the same
type design, this AD is being issued to detect and correct abrasion of
the Teflon sleeving and wires in the bundles of the fuel boost pumps
for the numbers 1 and 4 main fuel tanks, which could result in
electrical arcing between the wires and the aluminum conduit and
subsequent fire or explosion of the fuel tank. This AD requires a one-
time inspection to detect damage of the sleeving and wire bundles of
the forward and aft boost pumps of the numbers 1 and 4 main fuel tanks,
and of the auxiliary tank jettison pumps (if installed); replacement of
any damaged sleeving with new sleeving; and repair or replacement of
any damaged wires with new wires. For airplanes on which any burned
wires are found, this AD requires an inspection to detect damage of the
conduit, and replacement of any damaged conduit with a serviceable
conduit. The actions are required to be accomplished in accordance with
the alert service bulletin described previously.
This AD also requires that operators submit a report of inspection
results to the FAA. In addition, this AD requires that operators submit
damaged Teflon sleeving, wires, and conduits to the FAA.
Boeing Model 747 series airplanes having line numbers 433 and
subsequent are equipped with fuel pump wire conduits made from
corrosion-resistant steel (stainless steel). Arcing from the fuel pump
wires to the stainless steel conduit will result in opening the fuel
pump circuit breaker before sufficient heat is generated to penetrate
the stainless steel conduit. The FAA is considering additional
rulemaking to require replacing the aluminum conduits located in the
fuel tanks with stainless steel conduits following accomplishment of
the one-time inspection required by this AD. The details of the
requirement to replace the aluminum conduits with stainless steel
conduits will be finalized after reviewing the reports of inspection
results required by this AD.
Additionally, the FAA recognizes that the degree of wear or damage
to the parts may be difficult to describe in a written report of
inspection results. Consequently, the FAA finds it necessary to require
that any damaged parts be submitted to the FAA for examination.
Examination of these parts will enable the FAA to determine whether a
need exists to require future replacement of aluminum conduits with
stainless steel conduits, and to develop appropriate compliance times
based on the extent of wear or damage found.
[[Page 306]]
Justification of Compliance Time
The required compliance time of 120 days is usually sufficient to
allow for a brief comment period before adoption of a final rule. In
this AD, however, that compliance time was selected in order to allow
the requirements of the AD to be performed at a maintenance base where
special equipment and trained maintenance personnel will be available
without significant disruption of normal operations. Nevertheless, the
FAA has determined that immediate adoption is necessary in this case
because of the importance of initiating the required one-time
inspection as soon as possible.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications shall identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 96-NM-277-AD.'' The postcard will be date stamped and
returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new
airworthiness directive:
96-26-06 Boeing: Amendment 39-9870. Docket 96-NM-277-AD.
Applicability: Model 747 series airplanes having line numbers up
through 432, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (d) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To detect and correct abrasion of the Teflon sleeving and wires
in the bundles of the fuel boost pumps for the numbers 1 and 4 main
fuel tanks and of the auxiliary tank jettison pumps (if installed),
which could result in electrical arcing between the wires and the
aluminum conduit and subsequent fire or explosion of the fuel tank,
accomplish the following:
(a) Within 120 days after the effective date of this AD, perform
a one-time inspection to detect damage of the sleeving and wire
bundles of the forward and aft boost pumps of the numbers 1 and 4
main fuel tanks, and of the wire bundles of the auxiliary tank
jettison pumps (if installed), in accordance with Boeing Alert
Service Bulletin 747-28A2204, dated December 19, 1996.
(1) If any damaged sleeving is found, prior to further flight,
replace the sleeving with new sleeving in accordance with the alert
service bulletin.
(2) If any damaged wire is found, prior to further flight,
repair or replace the wire with new wire in accordance with the
alert service bulletin.
(3) If any burned wire is found, prior to further flight,
perform an inspection to detect damage of the conduit, in accordance
with the alert service bulletin. If any damage is found, prior to
further flight, replace the conduit with a serviceable conduit in
accordance with the alert service bulletin.
(b) Within 14 days after accomplishing the requirements of
paragraph (a) of this AD, submit a report of inspection results to
the Manager, Seattle Aircraft Certification Office (ACO), FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, WA
98055-4056; fax (206) 227-1181. The report shall include the
information specified in paragraphs (b)(1), (b)(2), (b)(3), (b)(4),
and (b)(5) of this AD. Information collection requirements contained
in this regulation have been approved by the Office of Management
and Budget (OMB) under the provisions of the Paperwork Reduction Act
of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control
Number 2120-0056.
(1) The airplane serial number.
(2) The total hours time-in-service accumulated on the airplane.
(3) The total number of flight cycles accumulated on the
airplane.
(4) A description of any damage found.
(5) The location where the damaged part was installed.
(c) If any damaged sleeving, wire, or conduit is found during
any inspection
[[Page 307]]
required by this AD, within 14 days after accomplishing the
inspection, submit the damaged part to the Manager, Seattle ACO,
along with the report of inspection results required by paragraph
(b) of this AD.
(d) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle ACO. Operators shall submit
their requests through an appropriate FAA Principal Maintenance
Inspector, who may add comments and then send it to the Manager,
Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(f) The actions shall be done in accordance with Boeing Alert
Service Bulletin 747-28A2204, dated December 19, 1996. This
incorporation by reference was approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part
51. Copies may be obtained from Boeing Commercial Airplane Group,
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be
inspected at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington; or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on January 21, 1997.
Issued in Renton, Washington, on December 23, 1996.
S. R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-33105 Filed 12-31-96; 12:23 pm]
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