[Federal Register Volume 59, Number 43 (Friday, March 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-4448]
[[Page Unknown]]
[Federal Register: March 4, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 93-NM-09-AD; Amendment 39-8845; AD 94-05-07]
Airworthiness Directives; Boeing Model 747 Series Airplanes,
Excluding Model 747-400 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to certain Boeing Model 747 series airplanes, that
currently requires repetitive visual inspections of wire bundles to
detect damage due to chafing, and repair of damaged wires. This
amendment revises the inspection and repair procedures, and provides a
terminating action, which, if accomplished, will eliminate the need for
the currently required inspections. This amendment is prompted by data
that substantiates the need for new inspection and repair procedures.
The actions specified by this AD are intended to prevent smoke and fire
in the cockpit emanating from wire bundles and loss of essential
cockpit instruments necessary for continued safe flight and landing of
the airplane.
DATES: Effective April 4, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of April 4, 1994.
ADDRESSES: 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 Federal
Aviation Administration (FAA), Transport Airplane Directorate, Rules
Docket, 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: Stephen Oshiro, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (206) 227-2793; fax (206)
227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations by superseding AD 92-27-12, Amendment 39-8447 (57
FR 61255, December 24, 1992), which is applicable to certain Boeing
Model 747 series airplanes, was published in the Federal Register on
June 3, 1993 (58 FR 31481). The action proposed to supersede AD 92-27-
12 to require revised repetitive visual inspections of wire bundles to
detect damage due to chafing, and repair or replacement of damaged
wires; and to clarify the location of the affected wire bundles above
the P6 panel. That action also would provide an optional terminating
action for the repetitive visual inspections.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter supports the proposed rule.
The Air Transport Association (ATA) of America, on behalf of one of
its members, requests an extension of the compliance time for the
proposed initial repetitive inspection of 120 days to 4,000 flight
hours for Model 747-100 series airplanes, since its airplanes were not
manufactured with BMS 13-51 type wire (Kapton insulated). The member
points out that the description of the wire bundle failure which
prompted issuance of AD 92-27-12 is typical for aromatic polyimid
(Kapton insulated) type wire bundles. The member notes the similarity
between that incident and the incident involving a Lockheed Model L-
1011 series airplane that prompted the FAA to issue AD 84-04-01,
Amendment 39-4815 (49 FR 6705, February 23, 1984). The member asserts
that neither AD 92-27-12 nor this proposal compare the different
failure modes and effects of aromatic polyimide (Kapton insulated) type
wiring with other types of wire insulation. Finally, the member notes
that the service history of Boeing Model 747-100 series airplanes
indicates that there have been no reported wire bundle chafing problems
in the area of concern.
The FAA does not concur on the basis of the following reasons:
The proposed AD addresses a potentially hazardous condition
involving the manner in which certain wire bundles were installed in
the affected airplanes. The type of insulation used on the wires is not
directly relevant to the hazardous condition. It is the position of the
FAA that the short circuit hazard will eventually occur on any Model
747-100, -200, or -300 series airplane with improperly installed wire
bundles, regardless of the type of wire insulation. The intent of the
proposed AD is to prevent the occurrence of a short circuit, not to
alter the failure mode and/or effects of such a failure. The relevance
of the type of wire insulation is limited to the amount of time
required for the short circuit to occur, once chafing has begun. Types
of wire utilizing harder, more abrasion resistant insulation will
endure chafing for longer periods of time before occurrence of a short
circuit. In this respect, Polyimide insulated wire could possibly be
superior to softer types of wire insulation, such as
Polytetrafluoroethylene (PTFE) insulated types of wire.
Further, the FAA points out that the Model L-1011 incident that
prompted the issuance of AD 84-04-01 was not the direct result of the
use of polyimide insulated wire. That incident was apparently due to
``* * * mechanical damage to wire insulation due to continuing chafing
* * *'' This information was published with that AD in the Federal
Register (49 FR 6705, February 23, 1984).
Additionally, the FAA has determined that the 120-day compliance
time for the proposed initial repetitive inspection is justified when
an additional hazard is considered, which was not present in the Model
L-1011 incident. The Model L-1011 incident resulted in a smoke and fire
hazard, due to an electrical fault of a window heat wire bundle. The
loss of the window heat function will not, in itself, result in an
immediate safety of flight hazard. In the case of the Model 747
incident that prompted issuance of AD 92-27-12, the electrical fault
resulted in the loss of numerous essential cockpit instruments
necessary for continued safe flight and landing, in addition to the
smoke and fire hazard.
Finally, the FAA disagrees that service experience should be used
to justify a reduction of the frequency of the repetitive inspection
intervals for Model 747-100 series airplanes. While the FAA does not
dispute the commenter's claim regarding lack of in-service chafing
incidents on the Model 747-100, the FAA points out that the wire
bundles above the P6 panel are installed on all Model 747-100, -200,
and -300 series airplanes in accordance with the same type design data.
As a result, the FAA cannot establish that the wire bundle installation
on Model 747-100 series airplanes has specific design features that
preclude these airplanes from the potential hazardous condition. The
FAA does recognize, however, that some of the airplanes affected by the
proposed AD may not exhibit the wire bundle chafing problem. For this
reason, paragraph (b)(2)(i) of the proposed AD provides for termination
of the repetitive inspections on airplanes that successfully pass a
wire bundle clearance inspection and measurement procedure.
ATA, on behalf of one of its members, requests that proposed
paragraph (c) only cite the original issue of Boeing Service Bulletin
747-24A2186, dated January 14, 1993, since Revision 1, dated May 20,
1993, contains several typographical errors. The FAA partially concurs.
The FAA clarifies that Revision 1 erroneously refers to military
specification MIL-I-42852 and MIL-I-46853 insulating tapes in several
paragraphs. MIL-I-46852 tape is the correct military specification
number and should be inserted wherever MIL-I-42852 or MIL-I-46853 is
identified. The FAA points out that Revision 1 of the service bulletin
contains descriptive information not found in the original release of
the service bulletin, which may assist operators in performing the
optional wire bundle modification. The FAA has included a statement in
paragraph (c) of this AD to clarify that MIL-I-46852 tape shall be
utilized wherever MIL-I-42852 tape or MIL-I-46853 tape is specified,
for those operators that incorporate Revision 1 of the service
bulletin. Therefore, with this information included in the AD, the FAA
considers that the service bulletin references are appropriate in
paragraph (c) of this AD.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the change previously
described. The FAA has determined that this change will neither
increase the economic burden on any operator nor increase the scope of
the AD.
There are approximately 700 Model 747 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 184
airplanes of U.S. registry will be affected by this AD, that it will
take approximately 1.5 work hours per airplane to accomplish the
required actions, and that the average labor rate is $55 per work hour.
Based on these figures, the total cost impact of the AD on U.S.
operators is estimated to be $15,180, or $83 per airplane. This total
cost figure assumes that no operator has yet accomplished the
requirements of this AD.
Should an operator elect to accomplish the optional terminating
action that would be provided by this AD action, the number of work
hours required to accomplish it would be approximately 1 per airplane,
and the cost of required parts would be approximately $32 per airplane.
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.
For the reasons discussed above, I certify that this action (1) Is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it 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 14 CFR part
39 of the Federal Aviation Regulations as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8447 (57 FR
61255, December 24, 1992), and by adding a new airworthiness directive
(AD), amendment 39-8845, to read as follows:
94-05-07 Boeing: Amendment 39-8845. Docket 93-NM-09-AD. Supersedes
AD 92-27-12, Amendment 39-8447.
Applicability: Model 747 series airplanes, excluding Model 747-
400 series airplanes; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
Note 1: Paragraph (a) of this AD restates the requirement for
repetitive inspections contained in paragraphs (a) and (b) of AD 92-
27-12. The first inspection required by this AD must be performed
within the specified repetitive inspection interval after the last
inspection performed in accordance with paragraphs (a) and (b) of AD
92-27-12.
To prevent smoke and fire in the cockpit emanating from wire
bundles and loss of essential cockpit instruments necessary for
continued safe flight and landing of the airplane, accomplish the
following:
(a) Within 15 days after January 8, 1993 (the effective date of
AD 92-27-12, amendment 39-8447): Perform a visual inspection to
detect damage due to chafing of the wire bundles that extend between
the P6 and P7 panels at station 400, water line 385, right buttock
line 15, at Stringer 2 on the right-hand side, 6 inches aft of the
P6 panel. Pay particular attention to wire bundles W418, W718, W998,
and other bundles that cross over these bundles. Repeat the
inspection thereafter at intervals not to exceed 120 days until the
inspection required by paragraph (b) of this AD is accomplished. If
any damaged wire is found, prior to further flight, repair the wire
in accordance with Boeing Standard Wiring Practices Document, D6-
54446.
(b) Within the next 4,000 flight hours after the effective date
of this AD, accomplish the requirements of paragraphs (b)(1) and
(b)(2) of this AD in accordance with Boeing Alert Service Bulletin
747-24A2186, dated January 14, 1993; or Revision 1, dated May 20,
1993.
(1) Perform a visual inspection to detect damage due to chafing
of the wire bundles above the P6 panel around station 400, water
line 385, right buttock line 25 in accordance with the service
bulletin. Pay particular attention to wire bundles W418, W718, W998,
W1100, and W1362, and other bundles that cross over these bundles.
Accomplishment of this inspection terminates the repetitive
inspection requirements of paragraph (a) of this AD. If any damaged
wire is found, prior to further flight, repair or replace the wire
in accordance with Boeing Standard Wiring Practices Document, D6-
54446.
(2) Measure the clearance between the wire bundles in accordance
with the service bulletin.
(i) If the measured clearance between the wire bundles is 0.25
inch or greater: No further action is required by this AD.
(ii) If the measured clearance between the wire bundles is less
than 0.25 inch: Repeat the inspection required by paragraph (b)(1)
of this AD thereafter at intervals not to exceed 120 days.
(c) Installation of the wire modification in accordance with
Boeing Alert Service Bulletin 747-24A2186, dated January 14, 1993,
or Revision 1, dated May 20, 1993, terminates the repetitive
inspections required by paragraphs (a) and (b) of this AD. Operators
that incorporate Boeing Alert Service Bulletin 747-24A2186, Revision
1, dated May 20, 1993, shall utilize MIL-I-46852 tape wherever MIL-
I-42852 tape or MIL-I-46853 tape is specified in that service
bulletin.
(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 Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. 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 FAR
21.197 and 21.199 to operate the airplane to a location where the
requirements of this AD can be accomplished.
(f) The inspections, measurement, and modification shall be done
in accordance with Boeing Alert Service Bulletin 747-24A2186, dated
January 14, 1993; or Boeing Service Bulletin 747-24A2186, Revision
1, dated May 20, 1993. 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 April 4, 1994.
Issued in Renton, Washington, on February 22, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-4448 Filed 3-3-94; 8:45 am]
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