AD 2000-02-20

[Federal Register Volume 65, Number 23 (Thursday, February 3, 2000)]
[Rules and Regulations]
[Pages 5229-5235]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-2087]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-231-AD; Amendment 39-11538; AD 2000-02-20]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 Series Airplanes 
Equipped With General Electric Model CF6-80C2 Series Engines

AGENCY:  Federal Aviation Administration, DOT.

ACTION:  Final rule.

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SUMMARY:  This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 767 series airplanes, that 
currently requires tests, inspections, and adjustments of the thrust 
reverser system. That AD also requires installation of a terminating 
modification, and repetitive follow-on actions. This amendment reduces 
the repetitive intervals for the follow-on actions. This amendment is 
prompted by reports indicating that several center drive units (CDU's) 
of the thrust reverser system were returned to the manufacturer of the 
CDU's because of low holding torque of the CDU cone brake. The actions 
specified by this AD are intended to ensure the integrity of the fail 
safe features of the thrust reverser system by preventing possible 
failure modes in the thrust reverser control system that can result in 
inadvertent deployment of a thrust reverser during flight.

DATES:  Effective March 9, 2000.
    The incorporation by reference of Boeing Service Bulletin 767-
78A0081, Revision 1, dated October 9, 1997, is approved by the Director 
of the Federal Register as of March 9, 2000.
    The incorporation by reference of certain other publications, as 
listed in the regulations, was approved previously by the Director of 
the Federal Register as of August 18, 1995 (60 FR 36976, July 19, 
1995).

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) by superseding AD 95-13-12, 
amendment 39-9292 (60 FR 36976, July 19, 1995), as revised by AD 95-13-
12 R1, amendment 39-9528 (61 FR 9092, March 7, 1996); which is 
applicable to certain Boeing Model 767 series airplanes; was published 
in the Federal Register on June 14, 1999 (64 FR 31764). That action 
proposed to supersede AD 95-13-12 R1 to continue to require tests, 
inspections, and adjustments of the thrust reverser system. That action 
also proposed to continue to require installation of a terminating

[[Page 5230]]

modification, and repetitive follow-on actions. In addition, that 
action proposed to reduce the repetitive intervals for the follow-on 
actions.

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.

Request for Credit for Modifications Installed in Production

    One commenter, the airplane manufacturer, requests that paragraphs 
(c), (e), and (f) of the proposed AD [paragraphs (c), (f), and (h) of 
the final rule] be revised to provide credit for airplanes on which the 
third locking system was installed in production. The commenter states 
that Model 767 series airplanes having line numbers 475 and subsequent 
and equipped with General Electric Model CF6-80C2 series engines had a 
third locking system installed in production in accordance with 
Production Revision Record (PRR) B11481-70, and were not modified in 
accordance with Boeing Service Bulletin 767-78-0063, Revision 2, dated 
April 28, 1994, as specified in paragraph (c) of the proposed AD.
    The FAA concurs that credit should be provided for airplanes that 
had a third locking system installed in production. This third locking 
system is equivalent to that described in Boeing Service Bulletin 767-
78-0063, Revision 2. Therefore, paragraph (c) of the final rule has 
been revised to apply only to airplanes having line numbers 1 through 
474 inclusive, and NOTE 2 has been added to identify airplanes modified 
in production. In addition, paragraphs (f) and (h) of the final rule 
have been revised to clarify the compliance time for airplanes modified 
in production.

Request for Credit for Functional Tests Accomplished During 
Production

    One commenter, the airplane manufacturer, requests that paragraph 
(d) of the proposed AD [paragraphs (d) and (e) of the final rule] be 
revised to provide credit for airplanes on which the functional test of 
the cone brake of the center drive unit (CDU) was accomplished during 
production. The commenter states that a functional test is accomplished 
prior to delivery in accordance with procedures equivalent to those 
described in Boeing Service Bulletin 767-78A0081, Revision 1, dated 
October 9, 1997. The commenter states that an initial functional test 
equivalent to that specified in paragraph (d) of the proposed AD is 
effectively accomplished on newly delivered airplanes at zero hours 
time-in-service, and, therefore, the next functional test should be 
required at 1,000 hours time-in-service.
    The FAA concurs that credit should be provided for airplanes on 
which a functional test of the CDU cone brake was accomplished during 
production. The FAA agrees that the production functional test is 
equivalent to the functional test described in Boeing Service Bulletin 
767-78A0081, Revision 1. Therefore, paragraphs (d) and (e) of the final 
rule have been revised accordingly.

Request to Extend Interval for Repetitive Tests and Checks

    Three commenters request that the interval for the repetitive 
functional tests and operational checks specified in paragraphs (d) and 
(e) of the proposed AD be extended. Two of the commenters request that 
the interval be revised to ``on the maintenance (letter) check nearest 
to the 1000-hour frequency.'' The third commenter requests that the 
interval be revised to 90 days or 1,500 hours time-in-service, 
whichever occurs first. The commenters state that their scheduled 
maintenance intervals do not coincide with the 1,000-hour interval 
specified in the proposed AD. Two of the commenters state that they are 
currently performing these tests and checks every 4,000 hours and have 
not had any adverse findings.
    The FAA does not concur with the commenters' request to extend the 
interval for the repetitive functional tests and operational checks. 
The thrust reverser safety assessment developed by the airplane 
manufacturer for the Model 767 series airplane suggests a 650-hour 
interval for the functional test of the CDU cone brake. However, based 
on concerns about introducing errors through more frequent maintenance 
of the thrust reverser system, the FAA has determined that the 1,000-
flight-hour interval for the functional tests of both the CDU cone 
brake and the electro-mechanical brake, as proposed, represents the 
maximum interval of time allowable to ensure the integrity of the fail 
safe features of the thrust reverser system for those airplanes that 
have incorporated a third locking system. In addition, this interval is 
consistent with recent rulemaking for similar installations on other 
Boeing airplane models. No change to the final rule is necessary in 
this regard.

Explanation of Other Changes to the Final Rule

    The FAA's intent in paragraph (d) of the proposed rule was to 
require a functional test of the CDU cone brake within 1,000 hours 
time-in-service after the most recent test, or within 650 hours time-
in-service after the effective date of this AD, whichever occurs later. 
The compliance time stated in the proposed rule was within 1,000 hours 
time-in-service after the most recent test of the cone brake performed 
in accordance with paragraph (a) of this AD, or within 650 hours time-
in-service after the effective date of this AD, whichever occurs first. 
This statement was in error, in that the tests required by paragraph 
(a) of this AD do not include a test of the CDU cone brake. In 
addition, the statement ``whichever occurs first'' would have 
unnecessarily grounded airplanes. Therefore, the compliance time stated 
in paragraph (d) of the proposed rule has been corrected in the final 
rule, and new paragraphs (d)(1) and (d)(2) have been added to the final 
rule. In addition, the repetitive intervals for the test of the CDU 
cone brake that were specified in paragraphs (d)(1) and (d)(2) of the 
proposed rule are included as a new paragraph (e) of the final rule, 
and subsequent paragraphs have been renumbered accordingly.
    In addition, in the ``Explanation of Requirements of Proposed 
Rule'' section of the preamble of the NPRM, the FAA stated that this AD 
would continue to require ``various inspections and functional tests to 
detect discrepancies of the thrust reverser control and indication 
system, and correction of any discrepancy found.'' However, the FAA 
finds that the instructions for correcting discrepancies found during a 
functional test of the cone brake [as described in paragraph (d) of the 
proposed rule and paragraphs (d) and (e) of this final rule] or an 
operational check of the electro-mechanical brake [as described in 
paragraph (e) of the proposed rule and paragraph (f) of this final 
rule] were inadvertently omitted from the body of the proposed rule. 
Therefore, a new paragraph (g) has been added to the final rule to 
specify that, if a test or check specified in paragraph (d), (e), or 
(f) of this AD cannot be performed successfully, repairs must be 
accomplished and the test successfully performed prior to further 
flight. Subsequent paragraphs have been renumbered accordingly.
    Also, operators should note that paragraph (d) of the proposed rule 
specified the compliance time for the actions required by that 
paragraph in terms of hours time-in-service. However, other paragraphs 
in the proposed rule specified compliance times in flight hours. 
Therefore, for consistency of terminology, the FAA has revised 
paragraphs (d) and (e) of this final rule to specify the compliance 
time

[[Page 5231]]

in flight hours for the actions required by those paragraphs.

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.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the FAA may 
consider additional rulemaking.

Cost Impact

    There are approximately 143 Boeing Model 767 series airplanes 
equipped with General Electric Model CF6-80C2 series engines in the 
worldwide fleet. The FAA estimates that 45 airplanes of U.S. registry 
will be affected by this AD.
    The tests, inspections, and adjustments that are currently required 
by AD 95-13-12 R1, and retained in this AD, take approximately 30 work 
hours per airplane to accomplish, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact on U.S. operators of 
the currently required tests, inspections, and adjustments that are 
retained in this AD is estimated to be $81,000, or $1,800 per airplane, 
per inspection cycle.
    The terminating modification currently required by AD 95-13-12 R1, 
and retained in this AD, takes approximately 786 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Required parts will be provided by the manufacturer at no cost to the 
operator. Based on these figures, the cost impact on U.S. operators of 
the terminating modification required by this AD is estimated to be 
$2,122,200, or $47,160 per airplane.
    The repetitive operational checks required by AD 95-13-12 R1, and 
retained in this AD, take approximately 2 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact on U.S. operators of the repetitive 
operational checks required by this AD is estimated to be $5,400, or 
$120 per airplane, per operational check cycle.
    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. However, the FAA has been advised 
that all U.S.-registered airplanes have accomplished the terminating 
modification in accordance with the requirements of this AD. Therefore, 
the future economic cost impact of this rule on U.S. operators will not 
include those costs.

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 removing amendment 39-9528 (61 FR 
9092, March 7, 1996), and by adding a new airworthiness directive (AD), 
amendment 39-11538, to read as follows:

2000-02-20   Boeing: Amendment 39-11538. Docket 98-NM-231-AD. 
Supersedes AD 95-13-12 R1, Amendment 39-9528.

    Applicability: Model 767 series airplanes equipped with General 
Electric Model CF6-80C2 series 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 (i)(1) 
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 ensure the integrity of the fail safe features of the thrust 
reverser system by preventing possible failure modes in the thrust 
reverser control system that can result in inadvertent deployment of 
a thrust reverser during flight, accomplish the following:

Restatement of Requirements of AD 95-13-12 R1

Repetitive Tests, Inspections, and Adjustments

    (a) Within 30 days after August 18, 1995 (the effective date of 
AD 95-13-12 R1, amendment 39-9528), perform tests, inspections, and 
adjustments of the thrust reverser system in accordance with Boeing 
Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994.
    (1) Except as provided by paragraph (a)(2) of this AD, repeat 
all tests and inspections thereafter at intervals not to exceed 
3,000 flight hours until the modification required by paragraph (c) 
of this AD is accomplished.
    (2) Repeat the check of the grounding wire for the Directional 
Pilot Valve (DPV) of the thrust reverser in accordance with the 
service bulletin at intervals not to exceed 1,500 flight hours, and 
whenever maintenance action is taken that would disturb the DPV 
grounding circuit, until the modification required by paragraph (c) 
of this AD is accomplished.

Repair

    (b) If any of the tests and/or inspections required by paragraph 
(a) of this AD cannot be successfully performed, or if those tests 
and/or inspections result in findings that are unacceptable in 
accordance with Boeing Service Bulletin 767-78-0047, Revision 3, 
dated July 28, 1994; accomplish paragraphs (b)(1) and (b)(2) of this 
AD.
    (1) Prior to further flight, deactivate the associated thrust 
reverser in accordance with

[[Page 5232]]

Section 78-31-1 of Boeing Document D630T002, ``Boeing 767 Dispatch 
Deviation Guide,'' Revision 9, dated May 1, 1991; or Revision 10, 
dated September 1, 1992. After August 18, 1995, this action shall be 
accomplished only in accordance with Revision 10 of the Boeing 
document. No more than one reverser on any airplane may be 
deactivated under the provisions of this paragraph.
    (2) Within 10 days after deactivation of any thrust reverser in 
accordance with this paragraph, the thrust reverser must be repaired 
in accordance with Boeing Service Bulletin 767-78-0047, Revision 3, 
dated July 28, 1994. Additionally, the tests and/or inspections 
required by paragraph (a) of this AD must be successfully 
accomplished; once this is accomplished, the thrust reverser must 
then be reactivated.

Modification

    (c) For airplanes having line numbers 1 through 474 inclusive: 
Within 3 years after August 18, 1995, install a third locking system 
on the left- and right-hand engine thrust reversers in accordance 
with Boeing Service Bulletin 767-78-0063, Revision 2, dated April 
28, 1994.

New Requirements of this AD

    Note 2:  Model 767 series airplanes equipped with General 
Electric Model CF6-80C2 series engines and having line numbers 475 
and subsequent, on which Production Revision Record (PRR) B11481-70 
(which installs a third locking system on the left- and right-hand 
engine thrust reversers) has been incorporated, need NOT be modified 
in accordance with Boeing Service Bulletin 767-78-0063, Revision 2.


    Note 3:  Boeing Service Bulletin 767-78-0063, references General 
Electric (GE) Service Bulletin 78-135 as an additional source of 
service information for accomplishment of the third locking system 
on the thrust reversers. However, the Boeing Service Bulletin does 
not specify the appropriate revision level, and the GE service 
bulletin has a new Lockheed Martin title for the same service 
bulletin: Lockheed Martin Service Bulletin 78-135, Revision 4, dated 
September 30, 1996. The appropriate revision level for the GE 
Service Bulletin is Revision 3, dated August 2, 1994. The GE and 
Lockheed Martin service bulletins are identical, and either may be 
used for accomplishment of the action described previously.


    Note 4:  The actions specified in Lockheed Martin Service 
Bulletin 78-1007, Revision 1, dated March 18, 1997; and Lockheed 
Martin Service Bulletin 78-1020, Revision 2, dated March 20, 1997; 
may be accomplished simultaneously in conjunction with Boeing 
Service Bulletin 767-78-0063 for accomplishment of the installation 
of the thrust reverser bracket and the thrust reverser lock. 
(Accomplishment of these two service bulletins together achieves the 
same results as Lockheed Martin Service Bulletin 78-135, Revision 4, 
and is acceptable for compliance with Boeing Service Bulletin 767-
78-0063.)

Repetitive Tests and Checks

    (d) Perform a functional test to detect discrepancies of the 
cone brake of the center drive unit (CDU) on each thrust reverser, 
in accordance with Boeing Service Bulletin 767-78A0081, Revision 1, 
dated October 9, 1997, or Appendix 1 (including Figure 1), sections 
1.A.(2), 2.A., 2.C., and 2.D of this AD. Accomplish the functional 
test at the time specified in paragraph (d)(1) or (d)(2) of this AD, 
as applicable.
    (1) For airplanes on which the test required by paragraph (d) of 
AD 95-13-12 R1 has been accomplished prior to the effective date of 
this AD: Accomplish the functional test within 1,000 flight hours 
after the most recent test of the CDU cone brake performed in 
accordance with paragraph (d) of AD 95-13-12 R1, or within 650 
flight hours after the effective date of this AD, whichever occurs 
later.
    (2) For airplanes on which the test required by paragraph (d) of 
AD 95-13-12 R1 has NOT been accomplished prior to the effective date 
of this AD: Accomplish the functional test within 1,000 flight hours 
since the date of manufacture, or within 650 flight hours after the 
effective date of this AD, whichever occurs later.
    (e) Repeat the functional test of the CDU cone brake specified 
in paragraph (d) of this AD at the time specified in paragraph 
(e)(1) or (e)(2) of this AD, as applicable.
    (1) For Model 767 series airplanes, line numbers up to and 
including 474, equipped with thrust reversers that have not been 
modified in accordance with Boeing Service Bulletin 767-78-0063: 
Repeat the functional test of the CDU cone brake thereafter at 
intervals not to exceed 650 flight hours.
    (2) For Model 767 series airplanes, line numbers 475 and 
subsequent; and Model 767 series airplanes equipped with thrust 
reversers that have been modified in accordance with Boeing Service 
Bulletin 767-78-0063: Repeat the functional test of the CDU cone 
brake thereafter at intervals not to exceed 1,000 flight hours.
    (f) Within 1,000 flight hours after accomplishing the 
modification required by paragraph (c) of this AD or after the 
equivalent modification (Production Revision Record B11481-70) is 
incorporated in production, or within 1,000 flight hours after the 
effective date of this AD, whichever occurs later: Perform 
operational checks of the electro-mechanical brake in accordance 
with Appendix 1 (including Figure 1), sections 1.A.(1), 2.A., 2.B., 
and 2.D of this AD. Repeat the operational checks thereafter at 
intervals not to exceed 1,000 flight hours.

Repair

    (g) If any functional test or operational check required by 
paragraph (d), (e), or (f) of this AD cannot be successfully 
performed, prior to further flight, repair in accordance with Boeing 
Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997; or 
Appendix 1, section 2.B. and 2.C., of this AD; as applicable; and 
repeat the applicable test or check until successfully accomplished.

Terminating Action

    (h) Accomplishment of the modification required by paragraph (c) 
or installation of an equivalent modification (Production Revision 
Record B11481-70) in production, and accomplishment of periodic 
operational checks required by paragraphs (d), (e), and (f) of this 
AD, constitutes terminating action for the tests, inspections, and 
adjustments required by paragraph (a) of this AD.

Alternative Methods of Compliance

    (i)(1) 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.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 95-13-12, amendment 39-9292, are approved as 
alternative methods of compliance with this AD.

    Note 5:  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

    (j) 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

    (k) Except as provided by paragraphs (b), (d), and (e) of this 
AD, the actions shall be done in accordance with Boeing Service 
Bulletin 767-78-0047, Revision 3, dated July 28, 1994; Boeing 
Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994; and 
Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 
1997; as applicable.
    (1) The incorporation by reference of Boeing Service Bulletin 
767-78A0081, Revision 1, dated October 9, 1997, is approved by the 
Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Service Bulletin 
767-78-0047, Revision 3, dated July 28, 1994; and Boeing Service 
Bulletin 767-78-0063, Revision 2, dated April 28, 1994; was 
previously approved by the Director of the Federal Register, as of 
August 18, 1995 (60 FR 36976, July 19, 1995).
    (3) 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.
    (l) This amendment becomes effective on March 9, 2000.

Appendix 1

Thrust Reverser Electro-Mechanical Brake and CDU Cone Brake Test

1. General

    A. This procedure contains steps to do two checks:

[[Page 5233]]

    (1) A check of the holding torque of the electro-mechanical 
brake.
    (2) A check of the holding torque of the CDU cone brake.

2. Electro-Mechanical Brake and CDU Cone Brake Torque Check (Fig. 
1)

    A. Prepare to do the checks:
    (1) Open the fan cowl panels.
    B. Do a check of the torque of the electro-mechanical brake:
    (1) Do a check of the running torque of the thrust reverser 
system:
    (a) Manually extend the thrust reverser six inches and measure 
the running torque.
    (1) Make sure the torque is less than 10 pound-inches.
    (2) Do a check of the electro-mechanical brake holding torque:
    (a) Make sure the thrust reverser translating cowl is extended 
at least one inch.
    (b) Make sure the CDU lock handle is released.
    (c) Pull down on the manual release handle on the electro-
mechanical brake until the handle fully engages the retaining clip.

    Note:  This will lock the electro-mechanical brake.


    (d) With the manual drive lockout cover removed from the CDU, 
install a \1/4\ inch extension tool and dial-type torque wrench into 
the drive pad.

    Note:  You will need a 24-inch extension to provide adequate 
clearance for the torque wrench.


    (e) Apply 90 pound-inches of torque to the system.
    (1) The electro-mechanical brake system is working correctly if 
the torque is reached before you turn the wrench 450 degrees (1\1/4\ 
turns).
    (2) If the flexshaft turns more than 450 degrees before you 
reach the specified torque, you must replace the long flexshaft 
between the CDU and the upper angle gearbox.
    (3) If you do not get 90 pound-inches of torque, you must 
replace the electro-mechanical brake.
    (f) Release the torque by turning the wrench in the opposite 
direction until you read zero pound-inches.
    (1) If the wrench does not return to within 30 degrees of 
initial starting point, you must replace the long flexshaft between 
the CDU and upper angle gearbox.
    (3) Fully retract the thrust reverser.
    C. Do a check of the CDU cone brake:
    (1) Pull up on the manual release handle to unlock the electro-
mechanical brake.
    (2) Pull the manual brake release lever on the CDU to release 
the cone brake.

    Note:  This will release the pre-load tension that may occur 
during a stow cycle.


    (3) Return the manual brake release lever to the locked position 
to engage the cone brake.
    (4) Remove the two bolts that hold the lockout plate to the CDU 
and remove the lockout plate.
    (5) Install a \1/4\-inch drive and a dial type torque wrench 
into the CDU drive pad.

    CAUTION: DO NOT USE MORE THAN 100 POUND-INCHES OF TORQUE WHEN 
YOU DO THIS CHECK. EXCESSIVE TORQUE WILL DAMAGE THE CDU.

    (6) Turn the torque wrench to try to manually extend the 
translating cowl until you get at lease 15-pound inches.

    Note:  The cone brake prevents movement in the extend direction 
only. If you try to measure the holding torque in the retract 
direction, you will get a false reading.


    (a) If the torque is less than 15-pound-inches, you must replace 
the CDU.
    D. Return the airplane to its usual condition:
    (1) Fully retract the thrust reverser (unless already 
accomplished).
    (2) Pull down on the manual release handle on the electro-
mechanical brake until the handle fully engages the retaining clip 
(unless already accomplished).

    Note:  This will lock the electro-mechanical brake.


    (3) Close the fan cowl panels.

BILLING CODE 4910-13-P

[[Page 5234]]

[GRAPHIC] [TIFF OMITTED] TR03FE00.000



[[Page 5235]]


    Issued in Renton, Washington, on January 24, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-2087 Filed 2-2-00; 8:45 am]
BILLING CODE 4910-13-U