[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]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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