[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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