[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