AD 2000-01-05

[Federal Register Volume 65, Number 5 (Friday, January 7, 2000)]
[Rules and Regulations]
[Pages 1051-1055]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-374]



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Federal Register / Vol. 65, No. 5 / Friday, January 7, 2000 / Rules 
and Regulations

[[Page 1051]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-361-AD; Amendment 39-11502; AD 2000-01-05]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD) applicable to certain Boeing Model 747 series airplanes. That AD 
currently requires repetitive inspections and tests of the thrust 
reverser control and indication system on each engine, and corrective 
actions, if necessary; installation of a terminating modification; and 
repetitive operational checks of that installation, 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 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. This action identifies certain repetitive operational 
checks that were inadvertently omitted from the existing AD, and 
revises certain procedures for accomplishment of the operational checks 
and certain follow-on corrective actions.

DATES: Effective January 24, 2000.
    The incorporation by reference of certain publications as listed in 
the regulations was approved previously by the Director of the Federal 
Register as of September 15, 1999 (64 FR 47365, August 31, 1999).
    Comments for inclusion in the Rules Docket must be received on or 
before March 7, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-361-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 August 19, 1999, the FAA issued AD 99-18-
03, amendment 39-11269 (64 FR 47365, August 31, 1999), applicable to 
certain Boeing Model 747 series airplanes. That AD requires repetitive 
inspections and tests of the thrust reverser control and indication 
system on each engine, and corrective actions, if necessary; 
installation of a terminating modification; and repetitive operational 
checks of that installation, and repair, if necessary. That AD was 
prompted by the results of a safety review, which revealed that in-
flight deployment of a thrust reverser could result in significant 
reduction in airplane controllability. The actions required by that 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.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 99-18-03, the FAA finds that it 
inadvertently omitted reference to the accomplishment of repetitive 
operational checks; however, the Summary and Explanation of 
Requirements of the Rule sections both specified accomplishment of the 
repetitive operational checks. The FAA's intent in paragraph (d) of 
that AD was to require operators to perform repetitive operational 
checks at intervals not to exceed 3,000 flight hours following 
accomplishment of the initial operational check. Paragraph (d) of this 
AD has been revised accordingly.
    The FAA also has determined that the procedures in the Airplane 
Maintenance Manual (AMM) are inadequately defined to allow for 
accomplishment of the operational checks; therefore, the procedures are 
included in an appendix to this AD. Accordingly, this action revises 
paragraphs (d) and (e) of that AD to remove all references to the AMM 
for accomplishment of the operational checks, and replace those 
references with references to Appendix 1 (including Figure 1) of this 
AD, which describes the Gearbox Lock and Air Motor Brake Test 
procedures required for accomplishment of the operational checks.
    In addition, all references to the procedures specified in the 
Master Minimum Equipment List and the Dispatch Deviation Guide in 
paragraphs (b) and (e) of the existing AD have been removed because the 
FAA is unable to determine that an airplane is safe for operation if 
the thrust reverser functional tests are not successfully passed, or if 
the tests are unable to be performed. These procedures are retracted by 
the FAA because failure of the functional test might indicate that a 
fault or faults are present, which could lead to an uncommanded 
deployment of a thrust reverser during flight.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of this same type design, this AD 
supersedes AD 99-18-03 to continue to require repetitive inspections 
and tests of the thrust reverser control and indication system on each 
engine, and corrective actions, if necessary; installation of a 
terminating modification; and repetitive operational checks of that 
installation, and repair, if necessary. The actions are required to be 
accomplished in

[[Page 1052]]

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 the 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.

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 24 work hours (6 work hours per 
engine) to accomplish the required inspections and tests, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the inspections and tests required by this AD would be 
approximately $1,440 per airplane, per inspection/test cycle.
    It would require approximately 392 work hours to accomplish the 
required installation of provisional wiring, at an average labor rate 
of $60 per work hour. Required parts would cost approximately $22,298 
per airplane. Based on these figures, the cost impact of this 
modification required by this AD would be approximately $45,818 per 
airplane.
    It would require approximately 306 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 required by this AD would be 
approximately $18,360 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 approximately $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 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-361-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 removing amendment 39-11269 (64 FR 
47365, August 31, 1999), and by adding a new airworthiness directive 
(AD), amendment 39-11502, to read as follows:

2000-01-05 Boeing: Amendment 39-11502. Docket 99-NM-361-AD. 
Supersedes AD 99-18-03, Amendment 39-11269.

    Applicability: Model 747-100B, -200, -300, and SP series 
airplanes, equipped with Rolls Royce RB211-524B2, C2, and D4 
engines; certificated in any category, as listed in the following 
service bulletins:
    <bullet> Boeing Alert Service Bulletin 747-78A2148, dated June 
1, 1995;
    <bullet> Boeing Service Bulletin 747-78A2148, Revision 1, dated 
July 20, 1995;
    <bullet> Boeing Service Bulletin 747-78-2136, dated May 11, 
1995; and
    <bullet> Boeing Service Bulletin 747-78-2156, dated October 31, 
1996.

    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 (f) of 
this AD. The request should include an assessment of the

[[Page 1053]]

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:

Restatement of Requirements of AD 
99-18-03

Repetitive Inspections and Tests

    (a) Within 90 days after September 15, 1999 (the effective date 
of AD 99-18-03, amendment 39-11269): Perform the applicable 
inspections and tests of the thrust reverser control and indication 
system on each engine, in accordance with Part III.A. through III.G. 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-78A2148, dated June 1, 1995, or Boeing Service Bulletin 747-
78A2148, Revision 1, dated July 20, 1995. Repeat the applicable 
inspections and tests thereafter at intervals not to exceed 18 
months, until accomplishment of paragraph (c) of this AD.

Corrective Actions

    (b) If any inspection or test required by paragraph (a) of this 
AD cannot be successfully performed as specified in the service 
bulletin, or if any discrepancy is detected during any inspection or 
test, prior to further flight, repair in accordance with Boeing 
Alert Service Bulletin 747-78A2148, dated June 1, 1995, or Boeing 
Service Bulletin 747-78A2148, Revision 1, dated July 20, 1995. 
Additionally, prior to further flight, any failed inspection or test 
required by paragraph (a) of this AD must be repeated and 
successfully accomplished.

Modification

    (c) Within 36 months after September 15, 1999: Install an 
additional locking system on the thrust reversers in accordance with 
the Accomplishment Instructions of Boeing Service Bulletin 747-78-
2156, dated October 31, 1996. Prior to or concurrent with 
accomplishment of Boeing Service Bulletin 747-78-2156, dated October 
31, 1996: Accomplish Boeing Service Bulletin 747-78-2136, dated May 
11, 1995; and Rolls-Royce Service Bulletins RB.211-71-B545, Revision 
2, dated August 8, 1997, RB.211-71-B551, Revision 1, dated March 20, 
1998, and RB.211-78-B552, dated June 21, 1996.
    Accomplishment of these actions constitutes terminating action 
for the repetitive inspections and tests required by paragraph (a) 
of this AD.

Operational Checks

    (d) Within 3,000 flight hours after accomplishing the 
modification required by paragraph (c) of this AD, or within 1,000 
flight hours after September 15, 1999, 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

    (e) If any operational check required by paragraph (d) 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 (d) of this AD must be repeated and successfully 
accomplished. Continue to repeat the operational checks thereafter 
at intervals not to exceed 3,000 flight hours.

Alternative Methods of Compliance

    (f) 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 2: 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

    (g) 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

    (h) Except as provided by paragraphs (d) and (e) of this AD, the 
actions shall be done in accordance with the applicable service 
bulletins:
    <bullet> Boeing Service Bulletin 747-78-2136, dated May 11, 
1995;
    <bullet> Boeing Alert Service Bulletin 747-78A2148, dated June 
1, 1995;
    <bullet> Boeing Service Bulletin 747-78A2148, Revision 1, dated 
July 20, 1995;
    <bullet> Boeing Service Bulletin 747-78-2156, dated October 31, 
1996;
    <bullet> Rolls-Royce Service Bulletin RB.211-78-B552, dated June 
21, 1996;
    <bullet> Rolls-Royce Service Bulletin RB.211-71-B545, Revision 
2, dated August 8, 1997; or
    <bullet> Rolls-Royce Service Bulletin RB.211-71-B551, Revision 
1, dated March 20, 1998.

This incorporation by reference was approved previously by the 
Director of the Federal Register as of September 15, 1999 (64 FR 
47365, August 31, 1999). 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.
    (i) This amendment becomes effective on January 24, 2000.

Appendix 1--

Gearbox Lock and Air Motor Brake Test

A. General

    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:
    (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.


[[Page 1054]]


    (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 \1/
4\ 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 of More Than 30 Pound-Inches 
(3.4 Newton-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 \1/
4\ 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) Make 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 extensions 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-U

[[Page 1055]]

[GRAPHIC] [TIFF OMITTED] TR07JA00.000



    Issued in Renton, Washington, on January 3, 2000.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-374 Filed 1-6-00; 8:45 am]
BILLING CODE 4910-13-C