[Federal Register Volume 65, Number 54 (Monday, March 20, 2000)]
[Rules and Regulations]
[Pages 14838-14845]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-6490]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-22-AD; Amendment 39-11640; AD 2000-05-30]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
repetitive inspections to detect discrepancies of the cables, fittings, 
and pulleys of the engine thrust control cable installation, and 
replacement, if necessary. This AD also requires certain preventative 
actions on the engine thrust control cable installation for certain 
airplanes. This amendment is prompted by reports of failure of engine 
thrust control cables. The actions specified by this AD are intended to 
prevent such failures, which could result in a severe asymmetric thrust 
condition during landing, and consequent reduced controllability of the 
airplane.

DATES: Effective April 24, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 24, 2000.

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: Dionne M. Krebs, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2250; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on October 1, 1999 (64 
FR 53275). That action proposed to require repetitive inspections to 
detect discrepancies of the cables, fittings, and pulleys of the engine 
thrust control cable installation, and replacement, if necessary. The 
action also proposed to require certain preventative actions on the 
engine thrust control cable installation for certain airplanes.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter supports the proposed rule.

Request for Clarification of Applicability

    One commenter does not request a specific change to the proposal, 
but suggests that since Model 747-200B SUD and 747-200B SUD SF series 
airplanes are not specified in the applicability section of the 
proposed AD, those model airplanes are excluded from the proposal.
    The FAA does not concur with the commenter's statement. Although 
Model 747-200B SUD and 747-200B SUD SF series airplanes are not 
specified in the applicability section of the proposal, the FAA stated 
the applicability according to the airplane models identified in the 
747 type certificate data sheet (TCDS). All models of the airplane are 
encompassed by the identification in the TCDS. The FAA notes that the 
commenter previously modified its Model 747-200B series airplanes to 
stretched upper deck and special freighter configurations; however, 
since the Model 747-200B SUD and 747-200B SUD SF series airplanes are 
not specifically identified in the 747 TCDS, the FAA has determined 
that those modified airplanes are Model 747-200B series airplanes. 
Therefore the final rule does apply to the Model 747-200B SUD and 747-
200B SUD SF series airplanes. No change to the final rule is necessary.

Request for Extension of Compliance Time

    Two commenters request that the compliance time for the repetitive 
inspection intervals specified in paragraph (a) of the proposed AD be 
extended.
    The first commenter suggests that the inspection intervals 
correspond to its current maintenance program, which specifies a thrust 
control cable system inspection for the cables and pulleys from the 
fuselage outboard at ``1C'' check intervals, and the cables and pulleys 
internal to the fuselage at ``3C'' check intervals. (This commenter 
considers a ``C'' check interval to be 18 months.) The commenter states 
that it has no reports of significant damage or wear to the cables on 
airplanes in service or in check. It estimates that the 18-month 
repetitive inspection interval specified in the proposal would 
necessitate approximately 20 additional work hours for unscheduled seat 
and sidewall removals.
    The second commenter requests that the areas of the thrust control 
cable

[[Page 14839]]

system covered by the ceiling, sidewall, and floor panels located in 
the pressurized cabin area be inspected at its normal ``D'' check 
interval. (This commenter considers a ``D'' check interval to be 60 
months.) The commenter states that, as specified in the maintenance 
planning document, it has implemented an inspection to verify the 
integrity of the thrust control cables from the cockpit to the pylon 
area. However, the majority of its airplanes have an extended 280-inch 
upper deck, which makes it difficult to perform the detailed visual 
inspections for the upper deck area in accordance with the proposal. 
The commenter suggests that the areas not covered by the ceiling, 
sidewall, and floor panels located in the pressurized cabin area, as 
well as the wing and pylon area, can be inspected in accordance with 
paragraph (a) of the proposed rule.
    The FAA concurs with the first commenter's statement that the 
thrust control cable system inspection for the cables and pulleys from 
the fuselage outboard be accomplished at ``1C'' check intervals. The 
FAA chose an 18-month inspection interval in order to encompass the 747 
operators' current maintenance program for accomplishment of the 
inspection at ``1C'' check intervals. The FAA infers that the 18-month 
interval is consistent with the commenter's current inspection 
maintenance schedule of the thrust control cables and pulleys from the 
fuselage outboard. The FAA also concurs with the second commenter that 
the inspection interval required by paragraph (a) of the final rule is 
appropriate for those areas not covered by the ceiling, sidewall, and 
floor panels located in the pressurized cabin area, as well as the wing 
and pylon area.
    The FAA does not concur with the commenters' requests to extend the 
compliance time for the repetitive inspections of certain areas of the 
thrust control cable system to ``3C'' check or ``D'' check intervals 
per the commenters' current maintenance programs. When establishing the 
18-month inspection interval for the thrust control cable inspections, 
the FAA was aware that unscheduled maintenance actions, in addition to 
the operator's existing maintenance program, may be necessary. 
Additionally, the FAA is aware of thrust control cable failures on 
airplanes that should have been previously inspected in accordance with 
the inspection intervals and procedures recommended in the 
manufacturer's maintenance planning document. The second commenter 
provides no substantiating data relevant to its request for extending 
the repetitive inspection interval for certain areas of the thrust 
control cable system. Based on a review of the service experience for 
airplanes that should be utilizing the manufacturer's maintenance 
planning document to perform the thrust control cable inspections, the 
FAA has determined that the current inspection intervals have not 
prevented failures of the thrust control cables.
    In developing an appropriate compliance time for the repetitive 
inspections, the FAA considered not only the degree of urgency 
associated with addressing discrepancies of the thrust control cables, 
fittings, and pulleys, but other factors as well. Those factors include 
the recommendations of the manufacturer, and the practical aspect of 
accomplishing the repetitive inspections within an interval of time 
coinciding with normal scheduled maintenance for the majority of 
affected operators. Considering those factors, the FAA has determined 
that the compliance time of 18 months after the effective date of this 
AD represents the maximum interval in which the affected airlines can 
continue to operate without compromising safety. In view of those 
factors, and the amount of time that has already elapsed since issuance 
of the notice of proposed rulemaking, the FAA has determined that 
further delay of these inspections is, in general, not appropriate. The 
FAA may, however, approve a request for an adjustment of the compliance 
time under the provisions of paragraph (h) of this final rule if data 
are submitted to substantiate that such an adjustment would provide an 
equivalent level of safety. No change to the final rule is necessary.

Request to Allow Operator's Equivalent Procedures

    One commenter states that it has modified the nacelle strut idler 
pulley in accordance with the instructions specified in Boeing Service 
Bulletin 747-76-2067, Revision 1, and is performing inspections through 
its maintenance program at an interval of ``1D'' checks and/or ``1C'' 
checks. Therefore, with this inspection in place, the commenter notes 
that there is no need to comply with the requirements in paragraph (d) 
of the proposed rule.
    The FAA interprets this as a request that the commenter be allowed 
to use its own operator procedures to accomplish the actions required 
by paragraph (c)(2)(ii), as referenced in paragraph (d) of the final 
rule. Paragraph (d) of the final rule states, ``Where Boeing Service 
Bulletin 747-76-2067, Revision 1, dated November 19, 1987, specifies 
that the actions required by paragraph (c)(2)(ii) of this AD may be 
accomplished in accordance with an `operator's comparable procedure,' 
the actions must be accomplished in accordance with the applicable 
chapters of the Boeing 747 Maintenance Manual, as specified in the 
service bulletin.'' Paragraph (c)(2)(ii) of the final rule requires a 
detailed visual inspection to detect wear of the engine thrust control 
cables in any area where an aluminum-type pulley is installed. The 
intent of paragraphs (c)(2)(ii) and (d) of the final rule is to require 
the use of the standard inspection procedures provided in the Boeing 
747 Maintenance Manual when inspecting the thrust control cable after 
the replacement of an aluminum-type pulley. Since the commenter states 
that its airplanes have been modified in accordance with the 
instructions specified in the service bulletin, no further action is 
required by the commenter in this regard. However, the airplane 
manufacturer has determined that damaged components of a worn aluminum 
pulley could cause the thrust control cables to wear in any area where 
an aluminum-type pulley was installed; therefore, the FAA has 
determined that a one-time inspection of the thrust control cables as 
required by paragraph (c)(2)(ii) of this AD, in lieu of depending on 
the repetitive inspections required by paragraph (a) of the AD, is 
required to detect that wear. Therefore, no change to the final rule is 
necessary.

Proposed Repetitive Inspection Requirement

    One commenter does not request a specific change to the proposal, 
but suggests that the repetitive inspections identified in paragraph 
(a) of the proposed AD do not appear to be justified. The commenter 
reiterates from the proposal the statements that the thrust control 
cable failures were found on Model 757 and 767 series airplanes and 
that because of similar design, the thrust control cables could fail on 
other airplane models. The commenter states that the proposed AD does 
not identify what caused the thrust control cable failures on the Model 
757 and 767 series airplanes, where the thrust control cables failed, 
or how other airplane models could have a similar condition. The 
commenter also questions whether or not the thrust control cable 
failures could have been prevented with a modification or a one-time 
inspection. The commenter asks if the operators of the Model 757 and 
767 series airplanes that experienced the failures had a maintenance 
program in place to inspect the cables, and if so, when was the last 
maintenance inspection before the failures occurred.

[[Page 14840]]

    The commenter further notes that it inspects its thrust control 
cables and pulleys from the fuselage outboard at ``1C'' check 
intervals, and the cables internal to the fuselage at ``3C'' check 
intervals. (The commenter considers a ``C'' check interval to be 18 
months.) The commenter states that it has had no reports of significant 
damage or wear to the cables.
    In response to this commenter, the FAA is providing the following 
information, in general terms, to clarify the circumstances surrounding 
the thrust control cable failures on the Model 757 and 767 series 
airplanes. The first Model 757 failure event occurred on the right 
engine thrust control cable, which was severed by arcing with a cargo 
compartment light power wire. The failure condition was discovered 
while the airplane was at the gate, during engine start, when the 
flightcrew could not control the engine speed. The second Model 757 
failure event was due to thrust cable chafing with a window heat power 
supply cable. The failure condition was detected when, at stable 
cruise, the right thrust lever ``jumped back'' and at the same time, 
the right engine began to accelerate towards N1 redline, despite 
attempts by the flightcrew to hold back the right thrust lever to idle 
power. The Model 767 thrust control cable failure occurred during the 
engine start; at airplane push-back from the gate, the number 2 engine 
accelerated without command. Investigation revealed that the cause of 
the failure was a broken thrust control cable at a location adjacent to 
the right-hand wing root.
    In response to the commenter's question, there is no evidence in 
any of the aforementioned events that the operators were not following 
the manufacturer's maintenance planning document recommendation for 
thrust control cable inspections. The incident reports for those 
failure events did not provide data on how long it had been between 
thrust control cable inspections when the failures occurred. In AD's 
similar to this one, for Model 747 series airplanes, the FAA has 
required both modifications, as well as repetitive inspections, to 
address the hazard associated with failures of the thrust control 
cables on the Model 757 and 767 series airplanes.
    The proposed AD did not identify specific details of the Model 757 
or 767 series airplanes thrust control cable failures because the 
specific failure modes of the thrust control cables may not exist on 
the Model 747 series airplane. The unsafe condition addressed by this 
final rule relates to the effect of a thrust control cable failure on 
the controllability of the airplane. In that respect, certain Model 
747, 757, and 767 series airplanes have similar design characteristics 
so that when the engine control thrust ``B'' cable fails during 
landing, it changes the position of the thrust reverser directional 
control valve, causing the thrust reverser to stow and the engine to 
accelerate. The other engine(s) are not affected by the thrust control 
cable failure, and remains in full reverse. This severe asymmetric 
thrust condition during landing is the unsafe condition. None of the 
modifications required by paragraphs (b) through (g) of the final rule, 
nor those modifications specified in the associated AD's applicable to 
Model 757 or 767 series airplanes, change the effects of a thrust 
control ``B'' cable failure. The repetitive inspections required by 
paragraph (a) of the final rule are intended to detect wear and 
corrosion prior to thrust control cable failure. Such wear and 
corrosion could be caused by numerous problems, not just those problems 
addressed by the actions specified in paragraphs (b) through (g) of the 
final rule.
    Although modifications have been developed to address specifically 
identified failure modes of the thrust control cables, there is no 
available modification that will eliminate the unsafe condition. 
Therefore, the FAA has determined that repetitive inspections of the 
thrust control cable system are the only proactive method to alleviate 
the unsafe condition. Additionally, although the commenter reports that 
it has not yet identified areas of significant thrust control cable 
wear or damage during its regular maintenance intervals, the fact that 
wear and damage to the cables has been identified and addressed by the 
manufacturer supports the FAA's position that repetitive inspections 
are required to address the unsafe condition. No change to the final 
rule is necessary.

Explanation of Change Made to the Final Rule

    The FAA has revised Figure 1 of Appendix 1 in the final rule to 
correct the percentage of wear of each outer wire of the thrust control 
cables as illustrated. The correct percentage (40%) was specified in 
Appendix 1, Paragraph 2.B.(1) of the proposal. Figure 1 of Appendix 1 
in the proposal illustrated, ``Each outer wire worn less than 50%.'' 
Figure 1 of Appendix 1 in the final rule illustrates ``Each outer wire 
worn less than 40%.''

Conclusion

    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.

Cost Impact

    There are approximately 624 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 182 airplanes of U.S. registry 
will be affected by this AD.
    It will take approximately 3 work hours per airplane to accomplish 
the required inspection to verify the engine thrust control cable 
integrity, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the inspection required by this AD on 
U.S. operators is estimated to be $32,760, or $180 per airplane, per 
inspection cycle.
    For airplanes identified in Boeing Service Bulletin 747-76-2019 (30 
U.S.-registered airplanes), it will take approximately 4 work hours per 
airplane to accomplish the required modification, at an average labor 
rate of $60 per work hour. No parts are required. Based on these 
figures, the cost impact of the modification required by this AD on 
U.S. operators is estimated to be $7,200, or $240 per airplane.
    For airplanes identified in Boeing Service Bulletin 747-76-2067, 
Revision 1 (12 U.S.-registered airplanes), it will take approximately 6 
work hours per airplane to accomplish the required inspection of the 
nacelle strut idler pulleys, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the one-time 
inspection required by this AD on U.S. operators is estimated to be 
$4,320, or $360 per airplane.
    For airplanes identified in Boeing Service Bulletin 747-76A2068, 
Revision 3 (4 U.S.-registered airplanes), it will take approximately 16 
work hours per airplane to accomplish the required replacement, at an 
average labor rate of $60 per work hour. Required parts will cost 
approximately $2,000 per airplane. Based on these figures, the cost 
impact of the replacement required by this AD on U.S. operators is 
estimated to be $11,840, or $2,960 per airplane.
    For airplanes identified in Boeing Alert Service Bulletin 747-
76A2073, Revision 1 (12 U.S.-registered airplanes), it will take 
approximately 4

[[Page 14841]]

work hours per airplane to accomplish the required action, at an 
average labor rate of $60 per work hour. The cost of required parts 
will be minimal. Based on these figures, the cost impact of this 
required action on U.S. operators is estimated to be $2,880, or $240 
per airplane.
    Currently, there are no airplanes identified in Boeing Service 
Bulletin 747-53-2327, Revision 2, and subject to this AD, on the U.S. 
Register. However, should an affected airplane be imported and placed 
on the U.S. Register in the future, it would require approximately 1 
work hour to accomplish this required inspection, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
this one-time inspection would be $60 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

Regulatory Impact

    The regulations adopted herein will 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 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:
2000-05-30 Boeing: Amendment 39-11640. Docket 99-NM-22-AD.

    Applicability: Model 747-100, -100B, -100B SUD, -200B, -200C, -
200F, -300, SR, and SP series airplanes; certificated in any 
category; equipped with Pratt & Whitney Model JT9D-3 or -7 series 
engines, General Electric Model CF6-45 or -50 series engines, or 
Rolls-Royce Model RB211-524B, C, or D series engines.

    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 (h) 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 prevent engine thrust control cable failures, which could 
result in a severe asymmetric thrust condition during landing, and 
consequent reduced controllability of the airplane, accomplish the 
following:

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Repetitive Inspections

    (a) For all airplanes: Within 18 months after the effective date 
of this AD, accomplish the ``Thrust Control Cable Inspection 
Procedure'' specified in Appendix 1 (including Figure 1) of this AD 
to verify the integrity of the engine thrust control cables. Prior 
to further flight, replace any discrepant component found, in 
accordance with the procedures described in the Boeing 747 
Maintenance Manual. Repeat the detailed visual inspection thereafter 
at intervals not to exceed 18 months.

Modification

    (b) For airplanes identified in Boeing Service Bulletin 747-76-
2019, dated June 9, 1971: Within 18 months after the effective date 
of this AD, modify the strut bulkhead assembly to enlarge the holes 
(2 places in each strut) through which the engine thrust control 
cables pass, in accordance with the service bulletin.

Inspection/Replacement

    (c) For airplanes equipped with General Electric Model CF6 
series engines and identified in Boeing Service Bulletin 747-76-
2067, Revision 1, dated November 19, 1987: Within 18 months after 
the effective date of this AD, perform a one-time inspection of each 
nacelle strut idler pulley to determine the type of pulley 
installed, in accordance with the service bulletin.

    Note 3: This paragraph does not apply to airplanes equipped with 
Pratt & Whitney Model JT9D-70 engines.

    (1) If no aluminum-type pulley is installed, no further action 
is required by this paragraph.
    (2) If any aluminum-type pulley is installed, prior to further 
flight, accomplish paragraphs (c)(2)(i) and (c)(2)(ii) of this AD in 
accordance with the service bulletin.
    (i) Replace any aluminum-type pulley with a phenolic-type pulley 
having Boeing part number BACP30F4.
    (ii) Except as provided by paragraph (d) of this AD: Perform a 
detailed visual inspection of the engine thrust control cables in 
any area where an aluminum-type pulley was installed, to detect 
wear. If any wear outside the criteria contained in Chapter 20-21-03 
of the Boeing 747 Maintenance Manual is found, prior to further 
flight, replace the cable with a new cable, in accordance with the 
service bulletin. If any wear within the criteria contained in the 
maintenance manual is found, no further action is required by this 
paragraph.

    Note 4: Accomplishment of the actions specified in Boeing 
Service Bulletin 747-76-2067, dated September 26, 1986, is 
acceptable for compliance with the actions required by paragraph (c) 
of this AD.

    (d) Where Boeing Service Bulletin 747-76-2067, Revision 1, dated 
November 19, 1987, specifies that the actions required by paragraph 
(c)(2)(ii) of this AD may be accomplished in accordance with an 
``operator's comparable procedure,'' the actions must be 
accomplished in accordance with the applicable chapters of the 
Boeing 747 Maintenance Manual, as specified in the service bulletin.

Replacement

    (e) For airplanes identified in Boeing Service Bulletin 747-
76A2068, Revision 3, dated August 22, 1991; including Notice of 
Status Change 747-76A2068 NSC 2, dated December 12, 1991: Within 18 
months after the effective date of this AD, replace aluminum idler 
pulley brackets with steel brackets, in accordance with paragraphs 
E., F., G., and H. of the Accomplishment Instructions of the service 
bulletin.

[[Page 14842]]

Inspection/Modification

    (f) For airplanes identified in Boeing Alert Service Bulletin 
747-76A2073, Revision 1, dated July 28, 1988: Within 18 months after 
the effective date of this AD, accomplish paragraphs (f)(1) and 
(f)(2) of this AD, in accordance with the alert service bulletin.
    (1) Perform a detailed visual inspection of the engine thrust 
control cables and pulley mounting bracket screws in the area aft 
and above main entry door number 2 on the left and right sides of 
the airplane to detect damage. If any damage is found, prior to 
further flight, replace the cable with a new cable.
    (2) Modify the pulley mounting bracket.

    Note 5: Accomplishment of the actions specified in Boeing Alert 
Service Bulletin 747-76A2073, dated February 4, 1988, is acceptable 
for compliance with the actions required by paragraph (f) of this 
AD.

Inspection/Modification/Replacement

    (g) For Model 747-100B SUD series airplanes identified in Boeing 
Service Bulletin 747-53-2327, Revision 2, dated September 24, 1998, 
with angle assemblies having Boeing part numbers 015U0454-63 and 
015U0454-64 installed at body station 970: Within 18 months after 
the effective date of this AD, perform a detailed visual inspection 
to measure the clearance between the engine thrust control cables 
and the cable penetration holes, in accordance with the Cable 
Chafing Inspection of the Accomplishment Instructions of the service 
bulletin. If insufficient clearance exists, as specified in the 
service bulletin, prior to further flight, accomplish paragraphs 
(g)(1) and (g)(2) of this AD.
    (1) Modify the cable penetration holes or replace the plate, as 
applicable, in accordance with Figure 7 of the service bulletin.
    (2) Perform a detailed visual inspection of the engine thrust 
control cables in any area of the plate to detect wear, in 
accordance with Chapter 20-21-03 of the Boeing 747 Maintenance 
Manual. If any wear outside the criteria contained in the 
maintenance manual is found, prior to further flight, replace the 
cable with a new cable, in accordance with the procedures described 
in the Boeing 747 Maintenance Manual. If any wear within the 
criteria contained in the maintenance manual is found, no further 
action is required by this paragraph.

Alternative Methods of Compliance

    (h) 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 6: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (i) 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.

Incorporation by Reference

    (j) Except as provided by paragraphs (a), (d), and (g)(2) of 
this AD, the actions shall be done in accordance with the following 
Boeing Service Bulletins, which contain the specified list of 
effective pages, as applicable:

----------------------------------------------------------------------------------------------------------------
                                            Page No.
  Service bulletin referenced and date      shown on    Revision level shown on         Date shown on page
                                              page                page
----------------------------------------------------------------------------------------------------------------
76-2019, June 9, 1971...................          1-6  Original.................  June 9, 1971.
747-76-2067, Revision 1, November 19,             1-4  1........................  November 19, 1987.
 1987.                                           5-12  Original.................  September 26, 1986.
747-76A2068, Revision 3, August 22, 1991      1, 3-30  3........................  August 22, 1991.
                                                    2  2........................  July 20, 1989.
Notice of Status Change 747-76A2068, NSC            1  Original.................  December 12, 1991.
 2, December 12, 1991.
747-76A2073, Revision 1, July 28, 1988..      1-4, 12  1........................  July 28, 1988.
                                             5-11, 13  Original.................  February 4, 1988.
747-53-2327, Revision 2, September 24,           1-80  2........................  September 24, 1998.
 1998.
----------------------------------------------------------------------------------------------------------------

    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.
    (k) This amendment becomes effective on April 24, 2000.

Appendix 1

Thrust Control Cable Inspection Procedure

1. General

    A. Clean the cables, if necessary, for the inspection, in 
accordance with Boeing 747 Maintenance Manual 12-21-05.
    B. Use these procedures to verify the integrity of the thrust 
control cable system. The procedures must be performed along the 
entire cable run for each engine. To ensure verification of the 
portions of the cables which are in contact with pulleys and 
quadrants, the thrust control must be moved by operation of the 
thrust and/or the reverse thrust levers to expose those portions of 
the cables.
    C. The first task is an inspection of the control cable wire 
rope. The second task is an inspection of the control cable 
fittings. The third task is an inspection of the pulleys.

    Note: These three tasks may be performed concurrently at one 
location of the cable system on the airplane, if desired, for 
convenience.

2. Inspection of the Control Cable Wire Rope

    A. Perform a detailed visual inspection to ensure that the cable 
does not contact parts other than pulleys, quadrants, cable seals, 
or grommets installed to control the cable routing. Look for 
evidence of contact with other parts. Correct the condition if 
evidence of contact is found.
    B. Perform a detailed visual inspection of the cable runs to 
detect incorrect routing, kinks in the wire rope, or other damage. 
Replace the cable assembly if:
    (1) One cable strand had worn wires where one wire cross section 
is decreased by more than 40 percent (see Figure 1),
    (2) A kink is found, or
    (3) Corrosion is found.
    C. Perform a detailed visual inspection of the cable: To check 
for broken wires, rub a cloth along the length of the cable. The 
cloth catches on broken wires.
    (1) Replace the 7x7 cable assembly if there are two or more 
broken wires in 12 continuous inches of cable or there are three or 
more broken wires anywhere in the total cable assembly.
    (2) Replace the 7x19 cable assembly if there are four or more 
broken wires in 12 continuous inches of cable or there are six or 
more broken wires anywhere in the total cable assembly.

3. Inspection of the Control Cable Fittings

    A. Perform a detailed visual inspection to ensure that the means 
of locking the joints are intact (wire locking, cotter pins, 
turnbuckle clips, etc.). Install any missing parts.
    B. Perform a detailed visual inspection of the swaged portions 
of swaged end fitting to detect surface cracks or corrosion. Replace 
the cable assembly if cracks or corrosion are found.

[[Page 14843]]

    C. Perform a detailed visual inspection of the unswaged portion 
of the end fitting. Replace the cable assembly if a crack is 
visible, if corrosion is present, or if the end fitting is bent more 
than 2 degrees.
    D. Perform a detailed visual inspection of the turnbuckle. 
Replace the turnbuckle if a crack is visible or if corrosion is 
present.

4. Inspection of Pulleys

    A. Perform a detailed visual inspection to ensure that pulleys 
are free to rotate. Replace pulleys which are not free to rotate.

BILLING CODE 4910-13-P

[[Page 14844]]

[GRAPHIC] [TIFF OMITTED] TR20MR00.000



[[Page 14845]]


    Issued in Renton, Washington, on March 10, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-6490 Filed 3-17-00; 8:45 am]
BILLING CODE 4910-13-C