[Federal Register Volume 68, Number 20 (Thursday, January 30, 2003)]
[Proposed Rules]
[Pages 4731-4737]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-2097]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-128-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 Series Airplanes 
Equipped With General Electric Model CF6-80C2 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747-
400 series airplanes, that currently requires repetitive tests of the 
cone brake of the central drive unit (CDU) of the thrust reversers, and 
corrective actions if necessary. This action would require installation 
of a thrust reverser actuation system (TRAS) lock and various related 
modifications and installations. Following installation of the TRAS 
lock, this action also would require repetitive functional tests of the 
TRAS lock, and corrective action if necessary. These actions are 
intended to prevent an inadvertent deployment of a thrust reverser 
during flight, which could result in loss of control of the airplane.

DATES: Comments must be received by March 17, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-128-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-128-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, 
Washington 98124-2207; and AlliedSignal Aerospace Services, PO Box 
52170, Phoenix, Arizona 85072-2170. This information may be examined at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 227-2686; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.

[[Page 4732]]

    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-128-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2002-NM-128-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 26, 2000, the FAA issued AD 2000-09-03, amendment 39-11711 
(65 FR 25829, May 4, 2000), to supersede AD 2000-02-33, amendment 39-
11551 (65 FR 5742). AD 2000-09-03 is applicable to certain Boeing Model 
747-400 series airplanes, and requires repetitive tests of the cone 
brake of the central drive unit (CDU) of the thrust reversers, and 
corrective actions if necessary. That action was prompted by a report 
indicating that completion of a cone brake test required by AD 2000-02-
33 was ineffective for certain airplanes. The requirements of that AD 
2000-09-03 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.

Actions Since Issuance of Previous Rule

    In the preamble to AD 2000-02-33, the FAA specified that the 
actions required by that AD were considered ``interim action'' and that 
the manufacturer was developing a modification to positively address 
the unsafe condition. We indicated that we might consider further 
rulemaking action once the modification was developed, approved, and 
available. The manufacturer now has developed such a modification, and 
we have determined that further rulemaking action is indeed necessary; 
this proposed AD follows from that determination.
    While the service information for installation of the modification 
has been available for some time, we have prioritized the issuance of 
ADs for corrective actions for the thrust reverser system on Boeing 
airplane models. 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. 
ADs that correct the same type of unsafe condition as would be 
addressed by this proposed AD have been issued previously for specific 
airplanes within the Boeing Model 737, 757, and 767 series.
    After the issuance of the service information related to the 
modification, we received a report from the airplane manufacturer 
indicating that there have been several incidents of failure of a 
connection shaft for the thrust reverser actuation system (TRAS) brake, 
which is installed as part of the modification. Such failure of the 
connection shaft would result in the TRAS lock being ineffective.
    Based on data on the connection shaft failures that have been 
collected by the airplane manufacturer to date, we have determined that 
we can best ensure the continued safety of the affected fleet of 
airplanes by proceeding with rulemaking at this time to propose to 
require installation of a TRAS lock on the thrust reversers on Model 
747-400 series airplanes. The airplane manufacturer is continuing to 
investigate the failures of the connection shaft. If the investigation 
reveals that corrective actions are necessary to prevent failure of the 
connection shaft, we may consider further rulemaking to mandate such 
corrective actions.

Explanation of Relevant Service Information

    We have reviewed and approved Boeing Service Bulletin 747-78-2151, 
Revision 1, dated August 21, 1997, as revised by Notice of Status 
Change (NSC) 747-78-2151 NSC 04, dated November 26, 1997, and NSC 747-
78-2151 NSC 05, dated December 18, 1997; and Boeing Service Bulletin 
747-78-2151, Revision 2, dated January 13, 2000. Those service 
bulletins describe procedures for completing the installation of and 
activating a TRAS lock on each thrust reverser. These procedures 
include replacing a certain microswitch pack with a new one; adding new 
wires; routing certain new wire bundles; changing certain wiring, 
circuit breakers, and components; installing thrust-reverser relay 
panels; and performing repetitive functional tests to ensure that the 
thrust reverser actuation system operates properly. In addition, those 
service bulletins refer to several other service bulletins that 
describe actions that must be accomplished prior to or concurrently 
with Boeing Service Bulletin 747-78-2151. These service bulletins, 
which describe various modifications and installations associated with 
the TRAS locks, are as follows:
    [sbull] Lockheed Martin Service Bulletin 78-1007, Revision 1, dated 
March 18, 1997, which describes procedures for installation of a 
bracket and fastening hardware for the TRAS lock on each thrust 
reverser.
    [sbull] Boeing Service Bulletin 747-78-2132, Revision 2, dated 
December 11, 1997, which describes procedures for installing wiring 
provisions for the TRAS lock in various areas of the airplane.
    [sbull] Lockheed Martin Service Bulletin 78-1020, Revision 2, dated 
March 20, 1997, which describes procedures for installing the TRAS lock 
(also called an electromechanical lock or brake) and a flexible drive 
cable on each thrust reverser.
    [sbull] Boeing Service Bulletin 747-31-2242, dated April 18, 1996, 
which describes procedures for installing new integrated display system 
software in six integrated display units and three electronic flight 
information/engine indication and crew alerting system (EICAS) 
interface units.
    [sbull] Boeing Service Bulletin 747-45-2016, Revision 1, dated May 
2, 1996, which describes procedures for replacing two central 
maintenance computers (CMCs) with new, improved CMCs, and installing 
new software for the CMCs.
    Accomplishment of the actions specified in these service bulletins 
is intended to adequately address the identified unsafe condition.
    We also have reviewed and approved Boeing Alert Service Bulletin 
747-78A2166, Revision 2, dated March 15, 2001. (AD 2000-09-03 refers to 
Boeing Service Bulletin 747-78A2166, Revision 1, dated October 9, 1997, 
as an appropriate source of service information for the functional test 
of the CDU cone brake and corrective actions on certain airplanes.) 
Among other things, Revision 2 of the service bulletin includes revised 
procedures for the functional test of the CDU cone brake that are 
appropriate for airplanes on

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which a TRAS lock has been installed, and procedures for a functional 
test of the TRAS lock. That service bulletin also specifies corrective 
action (e.g., replacement of a flexshaft and/or electromechanical 
gearbox with new or serviceable parts, and/or replacement of the TRAS 
lock (electromechanical brake) or CDU with new or serviceable parts) if 
any discrepancy is found during the functional test of the CDU cone 
brake or TRAS lock. We have revised paragraphs (a) and (c) under the 
heading ``Requirements of AD 2000-09-03'' in this proposed AD to 
include Boeing Alert Service Bulletin 747-78A2166, Revision 2, as an 
acceptable source of service information for actions in those 
paragraphs.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 2000-09-03 to continue to require 
repetitive tests of the CDU cone brake of the thrust reversers, and 
corrective actions if necessary. The proposed AD would add requirements 
for installation of a TRAS lock, and various related modifications and 
installations. The actions would be required to be accomplished in 
accordance with the service bulletins described previously, except as 
discussed below.

Explanation of Differences Between Service Bulletins and Proposed AD

    The new actions in this proposed AD would apply to Boeing Model 
747-400 series airplanes as listed in Boeing Service Bulletin 747-78-
2151, Revision 2. However, the effectivity listings of Boeing Service 
Bulletins 747-78-2132, Revision 2, 747-31-2242, and 747-45-2016, 
Revision 1, identify airplanes with line numbers other than those 
identified in Boeing Service Bulletin 747-78-2151, Revision 2, as being 
subject to the actions therein. We have coordinated with the airplane 
manufacturer on this issue, and the manufacturer agrees with our 
determination that, to be correct and complete, the new actions in 
paragraph (d) of this proposed AD should apply to Model 747-400 series 
airplanes as listed in Boeing Service Bulletin 747-78-2151, Revision 2.

Cost Impact

    There are approximately 145 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 8 airplanes of U.S. registry 
would be affected by this proposed AD.
    The functional test that is currently required by AD 2000-09-03 
takes approximately 12 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the currently required actions on U.S. operators is 
estimated to be $5,760, or $720 per airplane, per test cycle.
    The installations in Boeing Service Bulletin 747-78-2151, Revision 
2, would take approximately 410 work hours per airplane to accomplish, 
at an average labor rate of $60 per work hour. Required parts would be 
provided at no charge. Based on these figures, the cost impact of this 
proposed requirement on U.S. operators is estimated to be $196,800, or 
$24,600 per airplane.
    The installation specified in Lockheed Martin Service Bulletin 78-
1007, Revision 1, would take approximately 60 work hours per airplane 
to accomplish, at an average labor rate of $60 per work hour. Required 
parts would be provided at no charge. Based on these figures, the cost 
impact of this proposed requirement on U.S. operators is estimated to 
be $28,800, or $3,600 per airplane.
    The installation specified in Boeing Service Bulletin 747-78-2132, 
Revision 2, would take approximately 223 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts would cost between $32,219 and $36,562 per airplane. Based on 
these figures, the cost impact of this proposed requirement is 
estimated to be between $45,599 and $49,942 per airplane. The 
manufacturer may cover the cost of replacement parts associated with 
this service bulletin, subject to warranty conditions. As a result, the 
costs attributable to this proposed action may be less than stated 
above.
    The installation specified in Lockheed Martin Service Bulletin 78-
1020, Revision 2, would take approximately 16 work hours per airplane 
to accomplish, at an average labor rate of $60 per work hour. Required 
parts would be provided at no charge. Based on these figures, the cost 
impact of this proposed requirement on U.S. operators is estimated to 
be $7,680, or $960 per airplane.
    The installation specified in Boeing Service Bulletin 747-31-2242 
would take approximately 2 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. The cost of required parts 
would be negligible. Based on these figures, the cost impact of this 
proposed requirement is estimated to be $960, or $120 per airplane. The 
manufacturer may cover the cost of replacement parts and labor costs 
associated with accomplishment of this service bulletin, subject to 
warranty conditions. As a result, the costs attributable to this 
proposed action may be less than stated.
    The installation specified in Boeing Service Bulletin 747-45-2016, 
Revision 1, would take approximately 3 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. The cost of 
required parts would be negligible. Based on these figures, the cost 
impact of this proposed requirement is estimated to be $1,440, or $180 
per airplane. The manufacturer may cover the labor costs associated 
with accomplishment of this service bulletin, subject to warranty 
conditions. As a result, the costs attributable to this proposed action 
may be less than stated above.
    The functional test that would be required following installation 
of the TRAS lock would take approximately 12 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of this proposed requirement is 
estimated to be $5,760, or $720 per airplane, per test cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft

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regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 39-11711 (65 FR 
25829, May 4, 2000), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing: Docket 2002-NM-128-AD. Supersedes AD 2000-09-03, Amendment 
39-11711.

    Applicability: Model 747-400 series airplanes equipped with 
General Electric (GE) 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 (h)(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 prevent an inadvertent deployment of a thrust reverser during 
flight, which could result in loss of control of the airplane, 
accomplish the following:

Requirements of AD 2000-09-03

Repetitive Functional Tests

    (a) Within 1,000 hours time-in-service after the most recent 
test of the center drive unit (CDU) cone brake as specified in 
paragraph (b)(1) of AD 94-15-05, amendment 39-8976; or within 650 
hours time-in-service after May 19, 2000 (the effective date of AD 
2000-09-03, amendment 39-11711); whichever occurs later: Perform a 
functional test to detect discrepancies of the CDU cone brake on 
each thrust reverser as specified in paragraph (a)(1) or (a)(2) of 
this AD, as applicable.
    (1) For Model 747-400 series airplanes equipped with thrust 
reversers that have not been modified in accordance with Boeing 
Service Bulletin 747-78-2151 or a production equivalent: Perform the 
test in accordance with Boeing Service Bulletin 747-78A2166, 
Revision 1, dated October 9, 1997; or paragraph 3.C. of Boeing Alert 
Service Bulletin 747-78A2166, Revision 2, excluding Evaluation Form, 
dated March 15, 2001; or the applicable section of paragraph III.A. 
of the Accomplishment Instructions of Boeing Service Bulletin 747-
78A2113, Revision 2, dated June 8, 1995; or Revision 3, dated 
September 11, 1997. Repeat the test thereafter at intervals not to 
exceed 650 hours time-in-service.
    (2) For Model 747-400 series airplanes equipped with thrust 
reversers that have been modified in accordance with Boeing Service 
Bulletin 747-78-2151 or a production equivalent: Perform the test in 
accordance with Appendix 1 (including Figure 1) of this AD, or 
paragraph 3.C. of Boeing Alert Service Bulletin 747-78A2166, 
Revision 2, excluding Evaluation Form, dated March 15, 2001. After 
the effective date of this AD, only Boeing Alert Service Bulletin 
747-78A2166, Revision 2, may be used. Repeat the test thereafter at 
intervals not to exceed 1,000 hours time-in-service.

    Note 2: Accomplishment of the CDU cone brake test during 
production in accordance with Production Revision Record (PRR) 
80452-102 prior to May 19, 2000, is considered acceptable for 
compliance with the initial test required by paragraph (a) of this 
AD.


    Note 3: Model 747-400 series airplanes, line numbers 1061 and 
subsequent, equipped with GE CF6-80C2 engines, had a third locking 
system installed during production in accordance with Production 
Revision Record (PRR) 80452-102, and were not modified in accordance 
with Boeing Service Bulletin 747-78-2151 (which is a retrofit action 
for airplanes having line numbers 700 through 1060 inclusive).

Terminating Action

    (b) Accomplishment of the functional test of the CDU cone brake, 
as specified in paragraph (a) of this AD, constitutes terminating 
action for the repetitive tests of the CDU cone brake required by 
paragraph (b)(1) of AD 94-15-05.

Corrective Action

    (c) If any functional test required by paragraph (a) of this AD 
cannot be successfully performed as specified in the referenced 
service bulletin, or if any discrepancy is detected during any 
functional test required by paragraph (a) of this AD, accomplish 
either paragraph (c)(1) or (c)(2) of this AD.
    (1) Prior to further flight, repair in accordance with Boeing 
Service Bulletin 747-78A2166, Revision 1, dated October 9, 1997; 
Boeing Alert Service Bulletin 747-78A2166, Revision 2, excluding 
Evaluation Form, dated March 15, 2001; Boeing Service Bulletin 747-
78A2113, Revision 2, dated June 8, 1995; or Revision 3, dated 
September 11, 1997. After the effective date of this AD, only Boeing 
Alert Service Bulletin 747-78A2166, Revision 2; or Boeing Service 
Bulletin 747-78A2113, Revision 2 or Revision 3; may be used.
    (2) The airplane may be operated in accordance with the 
provisions and limitations specified in the operator's FAA-approved 
Minimum Equipment List (MEL), provided that no more than one thrust 
reverser on the airplane is inoperative.

New Requirements of This AD

Installation of Thrust Reverser Actuator System Lock and Associated 
Actions

    (d) For airplanes listed in Boeing Service Bulletin 747-78-2151, 
Revision 2, dated January 13, 2000: Within 36 months after the 
effective date of this AD, do paragraphs (d)(1) and (d)(2) of this 
AD.
    (1) Install and activate a thrust reverser actuator system 
(TRAS) lock on each thrust reverser per the Accomplishment 
Instructions of Boeing Service Bulletin 747-78-2151, Revision 1, 
excluding Evaluation Form, dated August 21, 1997; as revised by 
Notice of Status Change (NSC) 747-78-2151 NSC 04, dated November 26, 
1997; and NSC 747-78-2151 NSC 05, dated December 18, 1997; or Boeing 
Service Bulletin 747-78-2151, Revision 2, excluding Evaluation Form. 
The procedures for completing the installation and activating the 
TRAS lock include replacing a certain microswitch pack with a new 
one; adding new wires; routing certain new wire bundles; changing 
certain wiring, circuit breakers, and components; installing thrust-
reverser relay panels; and performing a functional test to ensure 
that the thrust reverser actuation system operates properly.
    (2) Prior to or concurrently with the installation required by 
paragraph (d)(1) of this AD, do the requirements of paragraphs 
(d)(2)(i), (d)(2)(ii), (d)(2)(iii), (d)(2)(iv), and (d)(2)(v) of 
this AD.
    (i) Install a bracket and fastening hardware for the third 
locking system on each thrust reverser, per Lockheed Martin Service 
Bulletin 78-1007, Revision 1, dated March 18, 1997.
    (ii) Install wiring provisions in various areas of the airplane, 
per the Accomplishment Instructions of Boeing Service Bulletin 747-
78-2132, Revision 2, excluding Evaluation Form, dated December 11, 
1997.
    (iii) Install a TRAS lock (also called an electromechanical lock 
or brake) and a flexible drive cable on each thrust reverser, per 
Lockheed Martin Service Bulletin 78-1020, Revision 2, dated March 
20, 1997.
    (iv) Install new integrated display system software in six 
integrated display units and three electronic flight information/
engine indication and crew alerting system (EICAS) interface units, 
per the Accomplishment Instructions of Boeing Service Bulletin 747-
31-2242, dated April 18, 1996.
    (v) Replace two central maintenance computers (CMCs), part 
number 622-8592-103, with new, improved CMCs, part number 622-8592-
105, and install new software for the CMCs, per the Accomplishment

[[Page 4735]]

Instructions of Boeing Service Bulletin 747-45-2016, Revision 1, 
dated May 2, 1996.

Repetitive Tests

    (e) For airplanes on which a TRAS lock is installed on the 
thrust reversers: Within 1,000 flight hours after the installation 
of the TRAS lock, or within 90 flight hours after the effective date 
of this AD, whichever is later, do a functional test of the TRAS 
lock (also called an electromechanical lock or brake) per the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
78A2166, Revision 2, excluding Evaluation Form, dated March 15, 
2001. Then, repeat this test at least every 1,000 flight hours. If 
the functional test cannot be successfully performed, before further 
flight, repair per the Accomplishment Instructions of the service 
bulletin, and repeat the test until it is successful.

Dispatch Limitations

    (f) If, prior to accomplishment of Boeing Service Bulletin 747-
78-2151 on any airplane, it becomes necessary to install a thrust 
reverser with the TRAS lock installed, dispatch of the airplane is 
allowed per the provisions and limitations specified in the 747-400 
Master Minimum Equipment List (MMEL), provided that the thrust 
reverser assembly that has the TRAS lock installed is deactivated 
per the 747-400 Dispatch Deviation Guide, Boeing Document D6U10151, 
dated June 28, 2002. Installation of a thrust reverser without a 
TRAS lock installed and reactivation of the thrust reverser must be 
accomplished within the time constraints specified in the MMEL.
    (g) If, after accomplishment of Boeing Service Bulletin 747-78-
2151 on any airplane, it becomes necessary to install a thrust 
reverser assembly that does not have the TRAS lock installed, 
dispatch of the airplane is allowed per the provisions and 
limitations specified in the Boeing Model 747-400 MMEL, provided 
that the thrust reverser assembly that does not have the TRAS lock 
installed is deactivated per the 747-400 Dispatch Deviation Guide, 
Boeing Document D6U10151, dated June 28, 2002. Installation of a 
thrust reverser with the TRAS lock installed and reactivation of the 
thrust reverser must be accomplished within the time constraints 
specified in the MMEL.

Alternative Methods of Compliance

    (h)(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. 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 2000-09-03, amendment 39-11711, are not 
considered to be approved as alternative methods of compliance with 
this AD.

    Note 4: 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

    (i) 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.

Appendix 1.--Thrust Reverser CDU Cone Brake Test

    1. This procedure contains steps to do a check of the holding 
torque of the CDU cone brake.
    2. CDU cone brake check (Figure 1):
    A. Prepare to do the check:
    (1) Open the fan cowl panels.
    (2) Pull up on the manual release handle to unlock the electro-
mechanical brake.
    (3) 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.

    (4) Return the manual brake release lever to the locked position 
to engage the cone brake.
    (5) Remove the two bolts that hold the lockout plate to the CDU 
and remove the lockout plate.
    (6) 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.
    (7) Turn the torque wrench to try to manually extend the 
translating cowl until you get at least 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.

    (8) If the torque is less than 15 pound-inches, you must replace 
the CDU.
    (9) Reinstall the lockout plate.
    B. 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

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    Issued in Renton, Washington, on January 23, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-2097 Filed 1-29-03; 8:45 am]
BILLING CODE 4910-13-C