[Federal Register Volume 65, Number 23 (Thursday, February 3, 2000)]
[Rules and Regulations]
[Pages 5222-5228]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-2089]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-76-AD; Amendment 39-11540; AD 2000-02-22]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 Series Airplanes 
Equipped with Rolls-Royce RB211-524G/H and RB211-524G-T/H-T Engines

AGENCY:  Federal Aviation Administration, DOT.

ACTION:  Final rule; request for comments.

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SUMMARY:  This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747-400 series airplanes. This 
action requires installation of a modification of the thrust reverser 
control and indication system and wiring on each engine; and repetitive 
operational checks of that installation to detect discrepancies, and 
repair, if necessary. This amendment is prompted by the results of a 
safety review, which revealed that in-flight deployment of a thrust 
reverser could result in a significant reduction in airplane 
controllability. The actions specified in this AD are intended to 
ensure the integrity of the fail-safe features of the thrust reverser 
system by preventing possible failure modes, which could result in 
inadvertent deployment of a thrust reverser during flight, and 
consequent reduced controllability of the airplane.

DATES:  Effective February 18, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 18, 2000.
    Comments for inclusion in the Rules Docket must be received on or 
before April 3, 2000.

ADDRESSES:  Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-76-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    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 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.

FOR FURTHER INFORMATION CONTACT:  Ed Hormel, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2681; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION:  On May 26, 1991, a Boeing Model 767-300ER 
series airplane was involved in an accident as a result of an 
uncommanded in-flight deployment of a thrust reverser. Following that 
accident, a study was conducted to evaluate the potential effects of an 
uncommanded thrust reverser deployment throughout the flight regime of 
the Boeing Model 747 series airplane. The study included a re-
evaluation of the thrust reverser control system fault analysis and 
airplane controllability. The results of the evaluation indicated that, 
in the event of thrust reverser deployment during high-speed climb 
using high engine power, these airplanes also could experience control 
problems. This condition, if not corrected, could result in possible 
failure modes in the thrust reverser control system, inadvertent 
deployment of a thrust reverser during flight, and consequent reduced 
controllability of the airplane.
    The FAA has prioritized the issuance of AD's for corrective actions 
for the thrust reverser system on Boeing airplane models following the 
1991 accident. Based on service experience, analyses, and flight 
simulator studies, it was determined that an in-flight deployment of a 
thrust reverser has more effect on controllability of twin-engine 
airplane models than of Model 747 series airplanes, which have four 
engines. For this reason, the highest priority was given to rulemaking 
that required corrective actions for the twin-engine airplane models. 
AD's correcting the same type of unsafe condition addressed by this AD 
have been previously issued for specific airplanes within the Boeing 
Model 737, 757 and 767 series.
    Service experience has shown that in-flight thrust reverser 
deployments have occurred on Model 747 airplanes during certain flight 
conditions with no significant airplane controllability problems being 
reported. However, the manufacturer has been unable to establish that 
acceptable airplane controllability would be achieved following these 
deployments throughout the operating envelope of the airplane. 
Additionally, safety analyses performed by the manufacturer and 
reviewed by the FAA have been unable to establish that the risks for 
uncommanded thrust reverser deployment during critical flight 
conditions are acceptably low.

Other Relevant Rulemaking

    This AD is related to AD 94-15-05, amendment 39-8976 (59 FR 37655, 
July 25, 1994), which is applicable to all Boeing Model 747-400 series 
airplanes, and requires various inspections and tests of the thrust 
reverser control and indication system, and correction of any 
discrepancy found. Accomplishment of the actions required by this AD 
would terminate certain inspections and tests required by AD 94-15-05.

Explanation of Relevant Service Information

    The FAA has reviewed and approved the following Boeing Service 
Bulletins:
     747-45-2016, Revision 1, dated May 2, 1996, and 747-45-
2007, dated March 29, 1990, which describe procedures for modifications 
to the central maintenance computer system hardware and software.
     747-73-2052, Revision 1, dated April 23, 1992, which 
describes procedures for modification of the fuel temperature 
indicating system. This service bulletin references Rolls-Royce Service 
Bulletin RB.211-71-9043, dated May 4, 1990, which describes additional 
procedures for modification of the fuel temperature indicating system. 
Accomplishment of Boeing Service Bulletin 747-73-2052, Revision 1, 
requires prior or concurrent accomplishment of Boeing Service Bulletin 
747-45-2007; and Rolls-Royce Service Bulletin RB.211-71-9043.
     747-31-2246, dated May 2, 1996, which describes procedures 
for modifications of the integrated display system software.
     747-78-2157, Revision 2, dated November 26, 1997, and 747-
78-2121, dated October 29, 1992, which describe procedures for the 
installation of provisional wiring for an additional thrust reverser 
locking device. These service bulletins reference the Boeing Standard 
Wiring Practices Manual, which describes wire installation and 
separation procedures.
     747-78-2158, Revision 2, dated July 29, 1999, which 
describes

[[Page 5223]]

procedures for installation of an additional locking system on the 
thrust reversers. This service bulletin references the following Rolls-
Royce Service Bulletins:
    --RB.211-71-9600, Revision 8, dated May 24, 1996; and RB.211-71-
9608, Revision 3, dated April 18, 1997, which describe procedures for 
the installation of provisions on the engines to accommodate the 
installation of an additional thrust reverser locking gearbox; and
    --RB.211-78-9601, Revision 5, dated February 20, 1998, which 
describes additional procedures for installation of an additional 
locking system on the thrust reversers; and
    --RB.211-78-B207, dated November 19, 1994, which describes 
procedures for installation of a thrust reverser translating cowl 
assembly seal support.
    --Accomplishment of Boeing Service Bulletin 747-78-2158 requires 
prior or concurrent accomplishment of the following service bulletins:
    1. Boeing Service Bulletin 747-45-2052, Revision 1;
    2. Boeing Service Bulletin 747-78-2121;
    3. Boeing Service Bulletin 747-45-2016, Revision 1;
    4. Boeing Service Bulletin 747-31-2246;
    5. Boeing Service Bulletin 747-78-2157, Revision 2;
    6. Rolls-Royce Service Bulletin RB.211-71-9600, Revision 8; and
    7. Rolls-Royce Service Bulletin RB.211-71-9608, Revision 3.
    In addition, this service bulletin requires concurrent 
accomplishment of Rolls-Royce Service Bulletins RB.211-78-9601, and 
RB.211-78-B207.
    The modification procedures described by Boeing Service Bulletin 
747-78-2158 were previously validated by the manufacturer, and the 
necessary changes have been incorporated into the latest revisions of 
the service bulletins. The FAA has determined that the procedures 
specified in Boeing Service Bulletin 747-78-2158, Revision 1, and 
Revision 2, as well as the other service bulletins referenced in this 
AD, have been effectively validated; therefore the FAA requires that 
this modification be accomplished. Several airplanes have been 
successfully modified in accordance with the service bulletins, and 
this past experience should minimize the likelihood for subsequent 
service bulletin revisions, requests for alternative methods of 
compliance, and superseding AD's.
    Accomplishment of the actions described in all service bulletins 
listed previously would eliminate the need for certain repetitive 
inspections and tests.

Explanation of Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to prevent possible failure modes that can result in 
inadvertent deployment of a thrust reverser during flight and 
consequent reduced controllability of the airplane. This AD requires 
installation of a modification of the thrust reverser control and 
indication system and wiring on each engine; and repetitive operational 
checks of that installation to detect discrepancies, and repair, if 
necessary. The actions are required to be accomplished in accordance 
with the service bulletins described previously, except as discussed 
below.
    Repetitive operational checks to detect discrepancies of the 
gearbox locks and the air motor brake are required to be accomplished 
in accordance with procedure included in Appendix 1 (including Figure 
1) of this AD. Correction of any discrepancy detected is required to be 
accomplished in accordance with the procedures described in the Boeing 
747 Airplane Maintenance Manual.

Differences Between Service Bulletin and This AD

    Operators should note that, although Boeing Service Bulletin 747-
78-2158, Revision 2, does not recommend a specific compliance time for 
accomplishment of the additional system lock installation, the FAA has 
determined that an unspecified compliance time would not address the 
identified unsafe condition in a timely manner. In developing an 
appropriate compliance time for this AD, the FAA considered not only 
the manufacturer's recommendation, but the degree of urgency associated 
with addressing the subject unsafe condition, the average utilization 
of the affected fleet, and the time necessary to perform the 
installation. In light of all of these factors, the FAA finds a 36-
month compliance time for completing the required actions to be 
warranted, in that it represents an appropriate interval of time 
allowable for affected airplanes to continue to operate without 
compromising safety.
    Operators also should note that, although the service bulletin does 
not specify operational checks of the actuation system lock 
installation following accomplishment of that installation, the FAA has 
determined that repetitive operational checks of the additional system 
lock on each thrust reverser will support continued operational safety 
of thrust reversers with actuation system locks.

Cost Impact

    None of the Model 747 series airplanes affected by this action are 
on the U.S. Register. All airplanes included in the applicability of 
this rule currently are operated by non-U.S. operators under foreign 
registry; therefore, they are not directly affected by this AD action. 
However, the FAA considers that this rule is necessary to ensure that 
the unsafe condition is addressed in the event that any of these 
subject airplanes are imported and placed on the U.S. Register in the 
future.
    Should an affected airplane be imported and placed on the U.S. 
Register in the future, it would require approximately 397 work hours 
to accomplish the required modifications, at an average labor rate of 
$60 per work hour. Required parts would be provided by the manufacturer 
at no cost to the operators. Based on these figures, the cost impact of 
the modifications required by this AD would be $23,820 per airplane.
    It would require approximately 185 work hours to accomplish the 
required installation of the locking gearbox, at an average labor rate 
of $60 per work hour. Required parts would be provided by the 
manufacturer at no cost to the operators. Based on these figures, the 
cost impact of the installation of the locking gearbox required by this 
AD would be $11,000 per airplane.
    It would require approximately 2 work hours to accomplish the 
required operational check, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the operational check 
required by this AD would be $120 per airplane, per check.

Determination of Rule's Effective Date

    Since this AD action does not affect any airplane that is currently 
on the U.S. register, it has no adverse economic impact and imposes no 
additional burden on any person. Therefore, prior notice and public 
procedures hereon are unnecessary and the amendment may be made 
effective in less than 30 days after publication in the Federal 
Register.

Comments Invited

    Although this action is in the form of a final rule and was not 
preceded by notice and opportunity for public comment, comments are 
invited on this rule. Interested persons are invited to comment on this 
rule by submitting such written data, views, or arguments as they may 
desire. Communications shall identify the Rules Docket number

[[Page 5224]]

and be submitted in triplicate to the address specified under the 
caption ADDRESSES. All communications received on or before the closing 
date for comments will be considered, and this rule may be amended in 
light of the comments received. Factual information that supports the 
commenter's ideas and suggestions is extremely helpful in evaluating 
the effectiveness of the AD action and determining whether additional 
rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-76-AD.'' The postcard will be date stamped and 
returned to the commenter.

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:

2000-02-22  Boeing: Amendment 39-11540. Docket 99-NM-76-AD.

    Applicability: Model 747-400 series airplanes equipped with 
Rolls-Royce RB211-524G/H engines, and RB211-524G-T/H-T 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 (d) 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 inadvertent deployment of a thrust reverser during 
flight and consequent reduced controllability of the airplane, 
accomplish the following:

Modifications

    (a) Accomplish the requirements of paragraphs (a)(1), (a)(2), 
and (a)(3) of this AD at the times specified in those paragraphs. 
Accomplishment of these actions, or installation of an additional 
locking system during production in accordance with production 
equivalent PRR 81000-39, constitutes terminating action for the 
inspections and tests required by paragraph (c) of AD 94-15-05, 
amendment 39-8976.
    (1) Within 36 months after the effective date of this AD: 
Install an additional locking system on each engine thrust reverser 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-78-2158, Revision 2, dated July 29, 1999.

    Note 2:  Modifications accomplished prior to the effective date 
of this AD in accordance with Boeing Service Bulletin 747-78-2158, 
Revision 1, dated January 22, 1998; are considered acceptable for 
compliance with the applicable action specified in this amendment.

    (2) Concurrent with the installation required by paragraph 
(a)(1) of this AD, accomplish the requirements of paragraphs 
(a)(2)(i) and (a)(2)(ii) of this AD.
    (i) Accomplish the additional procedures for installation of an 
additional locking system on each engine thrust reverser in 
accordance with Rolls-Royce Service Bulletin RB.211-78-9601, 
Revision 5, dated February 20, 1998.
    (ii) Install a thrust reverser translating cowl assembly seal 
support in accordance with Rolls-Royce Service Bulletin RB.211-78-
B207, dated November 19, 1994.
    (3) Prior to or concurrent with the installation required by 
paragraph (a)(1) of this AD, accomplish the requirements of 
paragraphs (a)(3)(i), (a)(3)(ii), (a)(3)(iii), and (a)(3)(iv) of 
this AD:
    (i) Modify the fuel temperature indicating system in accordance 
with Boeing Service Bulletin 747-73-2052, Revision 1, dated April 
23, 1992; and Rolls-Royce Service Bulletin RB.211-71-9043, dated May 
4, 1990. Prior to or concurrent with accomplishment of Boeing 
Service Bulletin 747-73-2052, Revision 1: Modify the central 
maintenance computer system (CMCS) hardware and software in 
accordance with Boeing Service Bulletin 747-45-2007, dated March 29, 
1990; and Boeing Service Bulletin 747-45-2016, Revision 1, dated May 
2, 1996.
    (ii) Install the provisional wiring for the locking system on 
the thrust reversers in accordance with Boeing Service Bulletin 747-
78-2121, dated October 29, 1992; and 747-78-2157, Revision 2, dated 
November 26, 1997.
    (iii) Modify the integrated display system (IDS) software in 
accordance with Boeing Service Bulletin 747-31-2246, dated May 2, 
1996.
    (iv) Install engine provisions to accommodate the installation 
of an additional locking system on each engine thrust reverser in 
accordance with Rolls-Royce Service Bulletin RB.211-71-9600, 
Revision 8, dated May 24, 1996; and RB.211-71-9608, Revision 3, 
dated April 18, 1997.

Repetitive Operational Checks

    (b) Within 3,000 flight hours after accomplishing the 
requirements of paragraph (a) of this AD, or within 1,000 flight 
hours after the effective date of this AD, whichever occurs later: 
Perform operational checks of the number 2 and number 3 gearbox 
locks and of the air motor brake, in accordance with the procedures 
described in Appendix 1 (including Figure 1) of this AD. Repeat the 
operational checks thereafter at intervals not to exceed 3,000 
flight hours.

Corrective Actions

    (c) If any operational check required by paragraph (b) of this 
AD cannot be successfully performed as specified in the procedures 
described in Appendix 1 (including Figure 1) of this AD, or if any 
discrepancy is detected during any operational check, prior to 
further flight, repair in accordance with the procedures specified 
in the Boeing 747 Airplane Maintenance Manual. Additionally, prior 
to further flight, any failed operational check required by 
paragraph (b) of this AD must be

[[Page 5225]]

repeated and successfully accomplished. Repeat the operational 
checks thereafter at intervals not to exceed 3,000 flight hours.

Alternative Methods of Compliance

    (d) 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

    (e) Special flight permits may be issued in accordance with 
Secs. 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

    (f) Except as provided by paragraphs (b), (c)(1), and (c)(2) of 
this AD, the actions shall be done in accordance with the applicable 
service bulletins, which contain the specified list of effective 
pages:

----------------------------------------------------------------------------------------------------------------
                                                                Revision level shown on
 Service bulletin referenced and date   Page No. shown on page            page              Date shown on page
----------------------------------------------------------------------------------------------------------------
Boeing 747-78-2157, Revision 2,        1-151..................  2                        November 26, 1997.
 November 26, 1997.
Boeing 747-78-2158, Revision 2, July   1-344..................  2                        July 29, 1999.
 29, 1999.
Boeing 747-73-2052, Revision 1, April  1, 3-5, 8, 10, 15-17...  1                        April 23, 1992.
 23, 1992.
                                       2, 6-7, 9, 11-14, 18-41  Original                 June 7, 1990.
Boeing 747-31-2246, May 2, 1996......  1-12...................  Original                 May 2, 1996.
Boeing 747-45-2016, Revision 1, May    1-33...................  1                        May 2, 1996.
 2, 1996.
Boeing 747-78-2121, October 29, 1992.  1-20...................  Original                 October 29, 1992.
Boeing 747-45-2007, March 29, 1990...  1-13...................  Original                 March 29, 1990.
Rolls-Royce RB.211-78-9601, Revision   1-4....................  5                        February 20, 1998.
 5, February 20, 1998.
                                       5......................  2                        October 20, 1995.
                                       6-21...................  Original                 August 7, 1992.
                                       Supplement.............
                                       1-3....................  4                        February 20, 1998.
Rolls-Royce RB.211-71-9600, Revision   1, 71-72, 72A..........  8                        May 24, 1996.
 8, May 24, 1996.
                                       2, 5-16, 18-32, 34-67,   2                        February 26, 1993.
                                        73-77, 87-88.
                                       3......................  7                        October 20, 1995.
                                       4......................  6                        March 31, 1995.
                                       17, 33, 86.............  4                        February 11, 1994.
                                       68-70, 78, 80-84.......  Original                 August 7, 1992.
                                       79, 85, 90-95..........  3                        December 17, 1993.
                                       89.....................  5                        August 19, 1994.
                                       Supplement.............
                                       1-5....................  3                        March 31, 1995.
Rolls-Royce RB.211-78-B207, November   1-15...................  Original                 November 19, 1994.
 19, 1994.
                                       Supplement.............
                                       1......................  Original                 November 19, 1994.
Rolls-Royce RB.211-71-9608, Revision   1, 5...................  3                        April 18, 1997.
 3, April 18, 1997.
                                       2-4, 6-18, 20-48.......  Original                 August 7, 1992.
                                       19.....................  2                        July 5, 1996.
                                       Supplement.............
                                       1-3....................  2                        April 18, 1997.
Rolls-Royce RB.211-71-9043, May 4,     1-18...................  Original                 May 4, 1990.
 1990.
                                       Supplement.............
                                       1-2....................  Original                 May 4, 1990.
----------------------------------------------------------------------------------------------------------------

    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.
    (g) This amendment becomes effective on February 18, 2000.

Appendix 1

1. Gearbox Lock and Air Motor Brake Test

A. General

    (1) To do the test of the gearbox locks and air motor brake, you 
must do the steps that follow:
    (a) Do the deactivation procedure of the thrust reverser system.
    (b) Do the test of the air motor brake.
    (c) Do the test of the gearbox locks.
    (d) Do the activation procedure of the thrust reverser system.

B. Equipment

    (1) CP30784--INA Access Platform, Rolls-Royce
    (2) CP30769--Protection Pads, Rolls-Royce
    (3) CP30785--Access Stools, Rolls-Royce
    (4) UT1293/1--Load Tool, Rolls-Royce (2 required)

C. Procedure (Fig. 1).

    WARNING: DO THE DEACTIVATION PROCEDURE OF THE THRUST REVERSER 
SYSTEM, WHICH MUST INCLUDE THE INSTALLATION OF LOCK BARS (OR 
BLOCKERS), TO PREVENT THE ACCIDENTAL OPERATION OF THE THRUST 
REVERSER. THE ACCIDENTAL OPERATION OF THE THRUST REVERSER COULD 
CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
    (1) Do the deactivation procedure of the thrust reverser in the 
forward thrust position for ground maintenance.
    (2) Use a 0.25 inch (6.4 mm) square drive to turn the manual 
lock release screw to release the No. 2 and No. 3 gearbox locks.


    Note:  It is not always easy to turn the manual lock release 
screws. This is because of a preload in the systems. To release the 
preload, lightly turn the manual cycle and lockout shafts in the 
stow direction.


    (a) Make sure the lock indicators are extended at gearboxes No. 
2 and No. 3.
    (3) Do a test of the air motor brake:
    (a) IF YOU USE THE LOAD TOOLS;
    Try to move the translating cowl in the extend direction as 
follows:

[[Page 5226]]

    (1) Remove the lock bars that you installed in the deactivation 
procedure.
    (2) Install the load tools through the cutouts and into the No. 
2 and No.3 gearboxes.
    (3) Attach the torque wrenches to the load tools.
    (4) Try to move the translating cowl in the extend direction.
    (b) IF YOU DO NOT USE THE LOAD TOOLS;
    Try to move the translating cowl in the extend direction as 
follows:
    (1) Remove the lock bars that you installed in the deactivation 
procedure.
    (2) Put the 0.25 inch (6.4 mm) square drive extensions into the 
manual cycle and lockout shaft at the No. 2 and No. 3 gearboxes.
    (a) Attach the standard drive tools.
    (3) Try to move the translating cowl in the extend direction.
    (c) If the translating cowl moves, replace the air motor and 
shutoff valve.
    (4) Do a test of the gear box locks:


    Note:  The steps that follow are for the No. 3 gearbox. Then, do 
these steps again for the No. 2 gearbox.


    (a) Install the lock bars in the manual cycle and lockout shafts 
at the No. 2 and No. 3 gearboxes.
    (b) Install the INA access platform in the exhaust mixer duct.
    (c) Install the protection pads and the access stools.
    (d) Release the air motor brake:
    (1) Open the air motor access and pressure relief panel.
    (2) Pull the air motor brake release handle forward and turn it 
counterclockwise to lock the handle in its position.
    (e) Turn the manual lock release screw clockwise to engage the 
No. 3 gearbox lock.
    (1) Make sure that the lock indicator is retracted (under the 
surface) at gearbox No. 3.
    (f) Make sure No. 2 gearbox lock is released.
    (1) Make sure the lock indicator is extended at gearbox No. 2.
    (g) IF YOU USE THE LOAD TOOLS; Do a check of the lock dogs as 
follows:
    (1) Remove the lock bars from the No. 2 and No. 3 gearboxes.
    (2) Install the load tool through the cutout and into the No. 3 
gearbox.
    (3) Attach the torque wrench to the load tool.
    CAUTION: DO NOT APPLY A TORQUE LOAD OF MORE THAN 30 POUND-INCHES 
(3.4 NEWTON-METERS) TO THE MANUAL CYCLE AND LOCK OUT SHAFT. A LARGER 
TORQUE LOAD CAN CAUSE DAMAGE TO THE MECHANISM.
    (4) Apply a torque counterclockwise through the manual wind 
position of the No. 3 gearbox.
    (a) If the translating cowl does not move, the lock bar touched 
one of the two lock dogs.
    (b) If the translating cowl moved, lock the thrust reverser 
until the No. 3 gearbox is replaced.
    (5) Turn the manual lock release screw counterclockwise to 
release the gearbox lock.
    (a) Make sure that the indication rod comes out of the No. 3 
gearbox.
    (6) Turn the manual cycle and lockout shaft counterclockwise a 
\1/4\ of a turn.
    (7) Turn the manual lock release screw clockwise to engage the 
No. 3 gearbox lock.
    (a) Make sure that the indication rod is fully retracted (under 
the surface).
    CAUTION: DO NOT APPLY A TORQUE LOAD OF MORE THAN 30 POUND-INCHES 
(3.4 NEWTON-METERS) TO THE MANUAL CYCLE AND LOCKOUT SHAFT. A GREATER 
TORQUE LOAD CAN CAUSE DAMAGE TO THE MECHANISM.
    (8) Apply a torque counterclockwise through the manual wind 
position of the No. 3 gearbox.
    (a) If the manual cycle and lockout shaft can not be turned more 
than approximately \1/4\ turn, the second lock dog is serviceable.
    (b) If the manual cycle and lockout shaft can be turned more 
than approximately \1/4\ turn, the second lock dog is unserviceable. 
Lock the thrust reverser until the No. 3 gearbox is replaced.


    Note:  The two lock dogs are found \1/2\ turn apart when you use 
the manual cycle and lockout shaft. If necessary, do the check again 
to make sure that the lock dogs are serviceable.


    (9) Do the procedure given above for the No. 2 gearbox lock.
    (h) IF YOU DO NOT USE THE LOAD TOOLS; Do a check of the lock 
dogs as follows:
    (1) Remove the lock bars from the No. 2 and No. 3 gearboxes.
    (2) Put the 0.25 inch (6.4 mm) square drive extensions into the 
manual cycle and lockout shaft at the No. 2 and No. 3 gearboxes.
    (a) Attach the standard drive tools.
    CAUTION: DO NOT APPLY A TORQUE LOAD OR MORE THAN 30 POUND-INCHES 
(3.4 NEWTOWN-METERS) TO THE MANUAL CYCLE AND LOCKOUT SHAFT. A LARGER 
TORQUE LOAD CAN CAUSE DAMAGE TO THE MECHANISM.
    (3) Apply a torque counterclockwise through the manual wind 
position of the No. 3 gearbox.
    (a) If the translating cowl does not move, the lock bar touched 
one of the two lock dogs.
    (b) If the translating cowl moved, lock the thrust reverser 
until the No. 3 gearbox is replaced.
    (4) Turn the manual lock release screw counterclockwise to 
release the gearbox lock.
    (a) Make sure that the indication rod comes out of the No. 3 
gearbox.
    (5) Turn the manual cycle and lockout shaft counterclockwise a 
\1/4\ of a turn.
    (6) Turn the manual lock release screw clockwise to engage the 
No. 3 gearbox lock.
    (a) Make sure that the indication rod is fully retracted (under 
the surface).
    CAUTION: DO NOT APPLY A TORQUE LOAD OF MORE THAN 30 POUND-INCHES 
(3.4 NEWTON-METERS) TO THE MANUAL CYCLE AND LOCKOUT SHAFT. A GREATER 
TORQUE LOAD CAN CAUSE DAMAGE TO THE MECHANISM.
    (7) Apply a torque counterclockwise through the manual wind 
position of the No. 3 gearbox.
    (a) If the manual cycle and lockout shaft can not be turned more 
than approximately \1/4\ turn, the second lock dog is serviceable.
    (b) If the manual cycle and lockout shaft can be turned more 
than approximately \1/4\ turn, the second lock dog is unserviceable. 
Lock the thrust reverser until the No. 3 gearbox is replaced.


    Note:  The two lock dogs are found \1/2\ turn apart when you use 
the manual cycle and lockout shaft. If necessary, do the check again 
to make sure that the lock dogs are serviceable.

    (8) Do the procedure given above for the No. 2 gearbox lock.
    (5) Install the lock bars in the manual cycle and lockout shafts 
at the No. 2 and No. 3 gearboxes.
    (6) Apply the air motor manual brake:
    (a) Turn the air motor brake release handle clockwise and then 
release.
    (b) Close the air motor access and pressure relief panel.
    (7) Make sure the No. 2 and No. 3 gearbox locks are released.
    (a) Makes sure the lock indicator rods are extended at the No.2 
and No. 3 gearboxes.
    (8) IF YOU USE THE LOAD TOOLS;
    Try to move the translating cowl in the extend direction as 
follows:
    (a) Remove the lock bars from the No. 2 and No. 3 gearboxes.
    (b) Install the load tools through the cutouts and into the No. 
2 and No. 3 gearboxes.
    (c) Attach the torque wrenches to the load tools.
    (d) Try to move the translating cowl in the extend direction.
    (9) IF YOU DO NOT USE THE LOAD TOOLS;
    Try to move the translating cowl in the extend direction as 
follows:
    (a) Remove the lock bars from the No. 2 and No. 3 gearboxes.
    (b) Put the 0.25 inch (6.4 mm) square drive extension into the 
manual cycle and lockout shaft at the No. 2 and No. 3 gearboxes.
    (1) Attach the standard drive tools.
    (c) Try to move the translating cowl in the extend direction.
    (10) If the translating cowl moves, do the full test again.
    (a) If the translating sleeve moves again, lock the thrust 
reverser until you can replace the two locking gearboxes and the air 
motor and shutoff valve.
    (11) Remove the access stools and protection pads.
    (12) Remove the INA access platform from the exhaust mixer duct.
    (13) Do the activation procedure of the thrust reverser system.
    (14) Do the functional test of the thrust reverser system.

BILLING CODE 4910-13-P

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[GRAPHIC] [TIFF OMITTED] TR03FE00.006


[[Page 5228]]



    Issued in Renton, Washington, on January 25, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-2089 Filed 2-2-00; 8:45 am]
BILLING CODE 4910-13-C