[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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