[Federal Register Volume 64, Number 200 (Monday, October 18, 1999)]
[Rules and Regulations]
[Pages 56151-56155]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26568]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-363-AD; Amendment 39-11363; AD 99-21-18]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 767 Series Airplanes
Powered by Pratt & Whitney JT9D-7R4 Series Turbofan Engines or General
Electric CF6-80A Series Turbofan Engines
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 767 series airplanes, that requires
repetitive inspections to detect certain discrepancies of the cables,
fittings, and pulleys of the engine thrust control cables; and repair,
if necessary. For certain airplanes, this amendment also requires
replacement of certain pulleys with new pulleys, and re-rigging of the
engine thrust control cable. This amendment is prompted by reports of
engine thrust control cable failures. 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 November 22, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of November 22, 1999.
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: Holly Thorson, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-1357; 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 767 series
airplanes was published in the Federal Register on April 14, 1999 (64
FR 18386). That action proposed to require modification of the engine
thrust control cable installation; repetitive inspections to detect
certain discrepancies of the cables, pulleys, pulley brackets, and
cable travel; and repair, if necessary. For certain airplanes, that
action also proposed to require replacement of certain pulleys with new
pulleys, and re-rigging of the engine thrust control cable.
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 AD.
Request for Clarification on Allowable Part Numbers
One commenter requests clarification on which part numbers of
aluminum pulleys will satisfy the intent of paragraph (b) of the
proposed AD. This commenter states that it has accomplished Boeing
Service Bulletin 767-76-0010, dated April 19, 1985, on its fleet. That
bulletin specifies replacement of the non-metallic pulleys of the
engine thrust control cable that are located in the leading edge of the
wing adjacent to the left and right engine strut, with aluminum pulleys
having the part number 255T1232-1. The proposed AD would require
pulleys to be replaced in accordance with Boeing Service Bulletin 767-
76-0010, Revision 1, dated February 20, 1992. That bulletin specifies
that replacement with aluminum pulleys having the part number 255T1232-
3 is preferred, but use of aluminum pulleys having the part number
255T1232-1 is allowed. The commenter states that, if aluminum pulleys
having the part number 255T1232-3 are the only approved pulleys, the
lack of availability of that pulley may cause unplanned delays in the
accomplishment of the proposed AD.
The FAA intends that paragraph (b) of this AD require replacement
of non-metallic pulleys of the engine thrust control cable that are
located in the leading edge of the wing adjacent to the left and right
engine strut, with aluminum pulleys having the part number 255T1232-1
or -3. Pulleys having the part number 255T1232-3 are preferred because
they use a different bearing that has high temperature grease. After
reviewing Boeing Service Bulletin 767-76-0010, dated April 19, 1985,
the FAA finds that accomplishment of the replacement specified in that
service bulletin is acceptable for compliance with the replacement
required by paragraph (b) of the final rule; therefore, a note stating
this has been added to the final rule.
Request for Information on Other Relevant Rulemaking
One commenter notes that the proposed rule states that the damage
criteria in Appendix 1., ``Thrust Control Cable Inspection Procedure,''
is based on the requirements in the Boeing 757 Maintenance Manual,
which are more stringent than the requirements for the Model 767 series
airplane. The commenter requests information regarding similar
rulemaking for the Boeing Model 757 series airplane. No specific change
to the rule is requested.
[[Page 56152]]
The FAA has issued two proposed rules to address the unsafe
condition on other Boeing airplane models that have an engine thrust
control cable installation similar to the Model 767 series airplane:
FAA Rules Docket No. 98-NM-323-AD (64 FR 49105, September
10, 1999), which applies to certain Model 757-200 series airplanes; and
FAA Rules Docket No. 99-NM-22-AD (64 FR 53275, October 1,
1999), which applies to certain Model 747 series airplanes.
No change to the final rule is necessary in this regard.
Request for Extension of the Compliance Time
Two commenters request that the compliance time for the repetitive
inspections specified in paragraph (a) of the proposed AD be extended.
One commenter suggests that its inspection program, which specifies
inspection of different sections of the engine thrust control cable
installation at intervals from 2,600 flight hours to 9,000 flight
hours, including inspections of certain sections to be performed only
on a sampling of airplanes in an operator's fleet, is adequate.
Therefore, reducing the interval by 50 percent, as specified in the
proposed AD, is unnecessary. The other commenter suggests that the
engine thrust control cables be inspected at every ``2C'' check, with
certain sections of the cable run to be inspected at every ``C'' check.
(This commenter considers a ``C'' check interval to be 456 days.) This
commenter states that it will have to modify its maintenance program to
accomplish the proposed repetitive inspections every 18 months or 4,500
flight hours.
The FAA does not concur with the commenters' request to extend the
compliance time. There has been one engine thrust control cable failure
on a Model 767 series airplane, and two failures on Model 757 series
airplanes. (The engine thrust control cable installation on certain
Model 757 series airplanes is similar to that on certain Model 767
series airplanes.) There was no evidence in these events that the
operators were not following the Boeing maintenance planning document
recommendations for the engine thrust control cable inspections. Given
this experience and the possibly catastrophic effect of a thrust
control cable failure, the FAA has determined that it is necessary to
conduct more frequent inspections of the cable installations.
Therefore, this AD requires the engine thrust control cable inspections
to be accomplished every 18 months or 4,500 flight hours, whichever
occurs first. No change to the final rule is necessary in this regard.
Request for Clarification of Applicability
One commenter requests clarification of the applicability of the
proposed AD. The commenter states that this proposed AD affects Model
767 series airplanes powered by Pratt & Whitney JT9D series turbofan
engines, and Model 767 series airplanes powered by General Electric CF6
series turbofan engines that do not use full authority digital
electronic controls (FADEC).
The FAA concurs partially. This AD only affects certain Model 767
series airplanes powered by General Electric CF6 series turbofan
engines that do not use FADEC (as well as Model 767 series airplanes
powered by Pratt & Whitney JT9D series turbofan engines). Specifically,
this AD affects Model 767 series airplanes powered by CF6-80A series
turbofan engines. The engine thrust control cable installation is
different on airplanes powered by other General Electric CF6 series
turbofan engines that do not use FADEC, and the unsafe condition
discussed previously does not exist on those airplanes. Therefore, no
change to the final rule is necessary in this regard.
Explanation of Changes Made to the Cost Impact
The FAA has been advised that the replacement of pulleys required
by paragraph (b) of this AD has been accomplished on 23 airplanes of
U.S. registry. Accordingly, the FAA has revised the cost impact, below,
to reflect this information.
Explanation of Changes Made to Appendix 1
Prompted by two comments received to FAA Rules Docket No. 98-NM-
323-AD (64 FR 7822, February 17, 1999), which proposed actions similar
to those required by this AD for the Model 757 series airplane, the FAA
reviewed Appendix 1., ``Thrust Control Cable Inspection Procedure,'' of
the proposed AD. One commenter to FAA Rules Docket No. 98-NM-323-AD
stated that the proposed procedure would require disassembly of the
engine thrust control cable installation. The other commenter suggested
that the procedure be revised to eliminate all steps that do not
contribute to the intent of the AD.
In FAA Rules Docket No. 98-NM-323-AD (the FAA issued a supplemental
NPRM for reasons other than the inspection procedure), the FAA
concurred with the commenters' request to revise the inspection
procedure. The FAA's intent was to define a thorough inspection of the
engine thrust control cable installation while minimizing the amount of
disruptive maintenance to the installation. With technical input from
the airplane manufacturer, an improved and simplified inspection
procedure has been developed, and Appendix 1. of this AD has been
revised accordingly. Figure 2 of Appendix 1. has been removed because
it is no longer needed for the inspection. The FAA has determined that
the revision, although extensive, does not change the intent of the
proposed procedure and actually decreases the scope of the inspection.
In addition, the FAA has revised certain language in the preamble of
this AD to reflect the changes to Appendix 1.
In addition, the FAA has corrected the summary of the final rule.
The summary of the proposed AD stated a modification of the engine
thrust control cable installation would be required on all affected
airplanes. No such requirement was included in the proposed AD.
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 changes previously
described. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
There are approximately 211 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 100 airplanes of U.S. registry
will be affected by this AD.
For all airplanes (100 U.S.-registered airplanes), it will take
approximately 3 work hours per airplane to accomplish the required
inspection, 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 $18,000, or $180 per airplane, per
inspection cycle.
For airplanes identified in Boeing Service Bulletin 767-76-0010,
Revision 1 (52 U.S.-registered airplanes), it will take approximately 9
work hours per airplane to accomplish the required replacement and re-
rigging, at an average labor rate of $60 per work hour. Required parts
will cost $484 per airplane. Based on these figures, the cost impact of
the replacement and re-rigging required by this AD on U.S. operators is
estimated to be $53,248, or $1,024 per airplane. The cost impact
figures
[[Page 56153]]
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. However, the FAA has been advised that 23 airplanes of
U.S. registry have been modified in accordance with Boeing Service
Bulletin 767-76-0010, Revision 1, as required by paragraph (b) of this
AD. Therefore, the future economic cost impact of the required
replacement and re-rigging on U.S. operators is now only $29,696, or
$1,024 per airplane.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
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:
99-21-18 Boeing: Amendment 39-11363. Docket 98-NM-363-AD.
Applicability: Model 767 series airplanes powered by Pratt &
Whitney JT9D-7R4 series turbofan engines or General Electric CF6-80A
series turbofan engines, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (c) 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 failure, which could
result in a severe asymmetric thrust condition during landing, and
consequent reduced controllability of the airplane, accomplish the
following:
(a) For all airplanes: Within 18 months or 4,500 flight hours
after the effective date of this AD, whichever occurs first,
accomplish the ``Thrust Control Cable Inspection Procedure''
specified in Appendix 1 (including Figure 1) of this AD to verify
the integrity of the thrust control cables. Prior to further flight,
repair any discrepancy found, in accordance with the procedures
described in the Boeing 767 Maintenance Manual. Repeat the
inspection thereafter at intervals not to exceed 18 months or 4,500
flight hours, whichever occurs first.
(b) For airplanes identified in Boeing Service Bulletin 767-76-
0010, Revision 1, dated February 20, 1992: Within 18 months or 4,500
flight hours after the effective date of this AD, whichever occurs
first, replace the two non-metallic pulleys of the thrust control
cable that are located in the leading edge of the wing adjacent to
the left and right engine strut with aluminum pulleys; and re-rig
the thrust control cables; in accordance with the service bulletin.
Note 2: Accomplishment of the replacement specified in Boeing
Service Bulletin 767-76-0010, dated April 19, 1985, is acceptable
for compliance with the replacement required by paragraph (b) of
this AD.
Alternative Methods of Compliance
(c) 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 3: 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
(d) 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
(e) The replacement and re-rigging specified in paragraph (b) of
this AD shall be done in accordance with Boeing Service Bulletin
767-76-0010, Revision 1, dated February 20, 1992. 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.
(f) This amendment becomes effective on November 22, 1999.
Appendix 1.--Thrust Control Cable Inspection Procedure
1. General
A. Clean the cables, if necessary, for the inspection, in
accordance with Boeing 767 Maintenance Manual 12-21-31.
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.
Note: For the purposes of this procedure, 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.''
2. Inspection of the Control Cable Wire Rope
A. Perform a detailed visual inspection to ensure that the cable
does not contact parts
[[Page 56154]]
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.
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 56155]]
[GRAPHIC] [TIFF OMITTED] TR18OC99.000
Issued in Renton, Washington, on October 4, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-26568 Filed 10-15-99; 8:45 am]
BILLING CODE 4910-13-C
