[Federal Register Volume 59, Number 154 (Thursday, August 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-18840]


[[Page Unknown]]

[Federal Register: August 11, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-178-AD; Amendment 39-8993; AD 94-16-03]

 

Airworthiness Directives; Boeing Model 767 Series Airplanes 
Equipped with Pratt & Whitney JT9D-7R4 or General Electric CF6-80A 
Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 767 series airplanes, that 
currently requires inspections, adjustments, and functional tests of 
the thrust reverser system. This amendment adds a requirement for 
installation of an additional thrust reverser system locking feature, 
periodic functional tests of that locking feature following its 
installation, and repair of any discrepancy found. This amendment is 
prompted by the identification of a modification that ensures that the 
level of safety inherent in the original type design of the thrust 
reverser system is further enhanced. The actions specified by this AD 
are intended to prevent possible discrepancies in the thrust reverser 
control system that can result in inadvertent deployment of a thrust 
reverser during flight.

DATES: Effective September 12, 1994.
    The incorporation by reference of Boeing Service Bulletin 767-78-
0060, Revision 2, dated August 19, 1993, and Boeing Service Bulletin 
767-78-0061, Revision 1, dated August 5, 1993, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
September 12, 1994.
    The incorporation by reference of Boeing Service Bulletin 767-78-
0054, dated December 13, 1991, and Boeing Service Bulletin 767-78-0053, 
dated December 13, 1991, as listed in the regulations, was approved 
previously by the Director of the Federal Register as of January 27, 
1992 (57 FR 3004, January 27, 1992).

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Richard Simonson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2683; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 92-03-03, 
amendment 39-8157 (57 FR 3004, January 27, 1992), which is applicable 
to certain Boeing Model 767 series airplanes, was published in the 
Federal Register on February 2, 1994 (59 FR 4870). The action proposed 
to require inspections, adjustments, and functional tests of the thrust 
reverser system; installation of an additional thrust reverser system 
locking feature; periodic functional tests of that locking feature 
following its installation; and repair of any discrepancy found.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposed rule.
    The Air Transport Association (ATA) of America, on behalf of its 
members, requests that a note or provision be added to the proposal to 
indicate that relief provided by the Master Minimum Equipment List 
(MMEL) is not revoked by the adoption of this AD. The commenter states 
that deactivation of a thrust reverser is not considered to be an 
unsafe procedure and is, therefore, not the subject of the proposed 
rule.
    The FAA concurs. The FAA agrees that certain relief may be provided 
to operators as requested by the commenter, and finds that the airplane 
may be operated in accordance with the provisions and limitations 
specified in the FAA-approved MMEL, provided that no more than one 
thrust reverser on an airplane is inoperative and that no synch-lock on 
that airplane is in an unlocked position. The FAA has revised paragraph 
(e) of the final rule accordingly.
    The ATA also questions the requirement contained in paragraph (e) 
of the proposal for repetitive functional tests of the synch-lock 
installation. The ATA states that its members are not opposed to 
accomplishing the proposed tests as part of their maintenance programs, 
but are opposed to accomplishing the tests as part of the requirements 
of an AD. The ATA reasons that the ``intent'' of the proposed rule is 
to terminate the tests required by AD 92-03-03.
    The ATA questions the rationale for the proposed repetitive 
functional tests of the synch-lock installation, since the synch-lock 
configuration has not been shown to be unsafe. The ATA acknowledges the 
FAA's statement in the Discussion section of the proposal that the 
synch-lock is a new design whose reliability has not been adequately 
proven through service experience. The ATA states that, under this 
rationale, an operator's maintenance program for newly certificated 
airplanes would simply consist of Certification Maintenance Requirement 
(CMR) items, since the reliability of newly designed systems has not 
been adequately proven through service experience. The ATA believes 
that AD control of the proposed repetitive tests is justified only if 
it can be shown that the tests cannot be administered safely within an 
operator's maintenance program.
    The ATA acknowledges that without issuance of an AD, the proposed 
repetitive tests may not be incorporated into every operator's 
maintenance program in a common manner at common intervals. In light of 
this consideration, the ATA requests that an alternative to 
accomplishment of the repetitive tests be provided in the final rule. 
The suggested alternative for paragraph (e) of the AD follows: Within 3 
months after accomplishing the synch-lock installation, revise the FAA-
approved maintenance inspection program to include a functional test of 
the synch-lock. The initial test would be accomplished within 1,500 
hours time-in-service after modification. The AD would no longer be 
applicable to operators that have acceptably revised their maintenance 
programs. Operators choosing this alternative could use an alternative 
recordkeeping method in lieu of that required by section 91.417 or 
section 121.380 of the Federal Aviation Regulation (14 CFR 91.417 or 
121.380). The FAA would be defined as the cognizant Principal 
Maintenance Inspector (PMI) for operators electing this alternative.
    The ATA believes that its proposal should be adopted because the 
proposed repetitive tests will likely continue for as long as Model 767 
series airplanes are operated. The ATA adds that, while there are 
numerous AD's that require repetitive inspections that would continue 
for the life of the aircraft, in such cases, either a satisfactory 
terminating action has not been developed or service experience has 
shown that control of the inspections cannot be safely administered 
through an operator's maintenance program. The ATA's proposal is 
intended to minimize the impact of the AD process on an operator's 
maintenance program.
    The FAA recognizes the concerns of the commenter regarding the 
requirement for periodic functional tests of the synch-lock following 
its installation, as required by paragraph (e) of this AD. However, the 
FAA has determined that such tests are necessary in order to provide an 
adequate level of safety and to ensure the integrity of the synch-lock 
installation. The actions required by this AD are consistent with 
actions that have been identified by an industry-wide task force as 
necessary to ensure adequate safety of certain thrust reverser systems 
installed on transport category airplanes. Representatives of the 
Aerospace Industries Association (AIA) of America, Inc., and the FAA 
comprise that task force. Representatives from other organizations, 
such as the ATA, have participated in various discussions and work 
activities resulting from the recommendations of the task force.
    The FAA acknowledges that the functional tests specified in 
paragraph (e) of this AD and CMR items are similar in terms of 
scheduled maintenance and recordkeeping. However, this AD addresses an 
unsafe condition and requires installation of the synch-lock to correct 
that unsafe condition. The FAA has determined that the requirement for 
functional tests is necessary in order to ensure the effectiveness of 
that installation in addressing that unsafe condition. As discussed in 
the preamble of the proposal, this determination is based on the fact 
that the synch-lock is a new design whose reliability has not been 
adequately proven through service experience. In addition, service 
experience to date has demonstrated that failures can occur within the 
synch-lock that may not be evident during normal operation of the 
thrust reverser system and may not result in activation of the synch-
lock ``unlock'' indicator. The FAA notes that the ATA's suggested 
alternative to accomplishment of the functional tests would permit each 
operator to determine whether and how often these tests should be 
conducted. In light of the severity of the unsafe condition, however, 
the FAA has determined that allowing this degree of operator discretion 
is not appropriate at this time. Therefore, this AD is necessary to 
ensure that operators accomplish tests of the integrity of the synch-
lock installation in a common manner and at common intervals.
    The ATA also requests that the proposed interval of 1,000 hours 
time-in-service for accomplishment of the repetitive functional tests 
specified in paragraph (e) of the proposal be extended to 1,500 hours 
time-in-service. The ATA explains that Boeing has recommended an 
interval of 4,000 hours time-in-service for inclusion in the next 
Maintenance Review Board (MRB) report. If the FAA denies an extension 
of the proposed interval, the ATA requests that the FAA explain why its 
analysis is so stringent in comparison with Boeing's recommendation. 
The ATA believes that AD compliance times should be consistent with 
operators' regularly scheduled maintenance unless a risk analysis 
requires otherwise. The ATA reasons that compliance times that are 
inconsistent with scheduled maintenance holds force operators to 
reschedule maintenance actions at considerable expense and disruption 
to their operations.
    The FAA has reconsidered the proposed interval of 1,000 hours time-
in-service for accomplishment of the initial and repetitive functional 
tests required by paragraph (e) of this AD. The FAA recognizes that an 
initial and repetitive interval of 4,000 hours time-in-service for 
accomplishment of these functional tests, as recommended by Boeing, 
corresponds more closely to the interval at which most of the affected 
operators conduct regularly scheduled ``C'' checks. In light of the 
safety implications of the addressed unsafe condition and the practical 
aspects of accomplishing orderly functional tests of the fleet during 
regularly scheduled maintenance where special equipment and trained 
maintenance personnel will be readily available, the FAA finds that 
accomplishment of the tests at intervals of 4,000 hours time-in-service 
will provide an acceptable level of safety. Paragraph (e) of the final 
rule has been revised accordingly.
    The ATA also requests that the cost of parts be included in the 
economic impact information, below, in order to present a total cost 
impact of the rule on the ``U.S. public.'' The ATA recognizes that 
Boeing plans to supply parts at no cost to operators; however, the ATA 
suspects the parts costs borne by Boeing would be substantial. The FAA 
does not concur with the commenter's request. The total cost impact 
figures shown in the economic impact information, below, represent the 
costs for time necessary to perform the inspections, adjustments, 
tests, and modification required by this AD. The cost analysis in AD 
rulemaking actions typically does not include parts costs when those 
parts are provided by the manufacturer at no cost to operators. Such 
costs are not attributable to the AD; the manufacturer would incur 
these costs even if no AD were issued.
    The FAA has revised paragraph (d) of the final rule to specify that 
the correct reference for Boeing Service Bulletin 767-78-0061 is 
Revision 1, rather than Revision 2, as cited in the proposal. The issue 
date of Revision 1 (August 5, 1993) appeared correctly in the proposed 
rule.
    The FAA also has revised paragraphs (a) and (b) of the final rule 
to clarify the appropriate compliance time. Those paragraphs restate 
requirements for accomplishment of certain actions required by AD 92-
03-03. The FAA's intent is that the tests, inspections, and adjustments 
required by those paragraphs would have been accomplished within 60 
days after January 27, 1992 (the effective date of AD 92-03-03).
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 119 Model 767 series airplanes equipped 
with General Electric CF6-80A series engines of the affected design in 
the worldwide fleet. The FAA estimates that 69 airplanes of U.S. 
registry will be affected by this AD. The inspections, adjustments, and 
functional tests required currently by AD 92-03-03 require 
approximately 16 work hours per airplane to accomplish the required 
actions, at an average labor rate of $55 per work hour. Based on these 
figures, the total cost impact of those actions on U.S. operators of 
Model 767 series airplanes equipped with General Electric CF6-80A 
series engines is estimated to be $60,720, or $880 per airplane.
    For U.S. operators of Model 767 series airplanes equipped with 
General Electric CF6-80A series engines, the FAA estimates that it will 
take approximately 786 work hours per airplane to accomplish the 
modification required by this AD, and 1 work hour to accomplish the 
required functional tests, at an average labor rate of $55 per work 
hour. Required parts will be supplied by the manufacturer at no cost to 
operators. Based on these figures, the total cost impact of those 
actions on U.S. operators of Model 767 series airplanes equipped with 
General Electric CF6-80A series engines is estimated to be $2,986,665, 
or $43,285 per airplane.
    There are approximately 95 Model 767 series airplanes equipped with 
Pratt & Whitney JT9D-7R4 series engines of the affected design in the 
worldwide fleet. The FAA estimates that 30 airplanes of U.S. registry 
will be affected by this AD. The inspections, adjustments, and 
functional tests required currently by AD 92-03-03 require 
approximately 16 work hours per airplane to accomplish the required 
actions, at an average labor rate of $55 per work hour. Based on these 
figures, the total cost impact of those actions on U.S. operators of 
Model 767 series airplanes equipped with Pratt & Whitney JT9D-7R4 
series engines is estimated to be $26,400, or $880 per airplane.
    For U.S. operators of Model 767 series airplanes equipped with 
Pratt & Whitney JT9D-7R4 series engines, the FAA estimates that it will 
take approximately 812 work hours per airplane to accomplish the 
modification required by this AD, and 1 work hour to accomplish the 
required functional tests, at an average labor rate of $55 per work 
hour. Required parts will be supplied by the manufacturer at no cost to 
operators. Based on these figures, the total cost impact of those 
actions on U.S. operators of Model 767 series airplanes equipped with 
Pratt & Whitney JT9D-7R4 series engines is estimated to be $1,341,450, 
or $44,715 per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    The number of required work hours for accomplishing the required 
functional tests, as indicated above, is presented as if the 
accomplishment of those tests required by this AD were to be conducted 
as ``stand alone'' actions. However, in actual practice, those tests 
for the most part will be accomplished coincidentally or in combination 
with normally scheduled airplane inspections and other maintenance 
program tasks. Therefore, the actual number of necessary additional 
work hours for accomplishment of the functional tests will be minimal 
in many instances. Additionally, any costs associated with special 
airplane scheduling will be minimal.
    The FAA recognizes that the required modification will require a 
large number of work hours to accomplish. However, the 5-year 
compliance time specified in paragraph (d) of this AD should allow 
ample time for the synch-lock installation to be accomplished 
coincidentally with scheduled major airplane inspection and maintenance 
activities, thereby minimizing the costs associated with special 
airplane scheduling.
    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-8157 (57 FR 
3004, January 27, 1992), and by adding a new airworthiness directive 
(AD), amendment 39-8993, to read as follows:

94-16-03 Boeing: Amendment 39-8993. Docket 93-NM-178-AD. Supersedes 
AD 92-03-03, Amendment 39-8157.
    Applicability: Model 767 series airplanes equipped with Pratt & 
Whitney JT9D-7R4 or General Electric CF6-80A series engines, 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure the integrity of the fail-safe features of the thrust 
reverser system, accomplish the following:

Restatement of Actions Required by AD 92-03-03

    (a) For airplanes equipped with Pratt & Whitney JT9D-7R4 series 
engines: Within 60 days after January 27, 1992 (the effective date 
of AD 92-03-03, amendment 39-8157), and thereafter at intervals not 
to exceed 3,000 flight hours, perform the tests, inspections, and 
adjustments described in Boeing Service Bulletin 767-78-0054, dated 
December 13, 1991.
    (1) Following any maintenance action that could affect the 
thrust reverser system: Repeat the tests, inspections, and 
adjustments required by paragraph (a) of this AD on the affected 
engine, prior to further flight, in accordance with the service 
bulletin.
    (2) Thereafter, following any maintenance action, continue to 
perform the repetitive tests, inspections, and adjustments required 
by paragraph (a) of this AD on the affected engine at intervals not 
to exceed 3,000 flight hours.
    (b) For airplanes equipped with General Electric CF6-80A series 
engines: Within 60 days after January 27, 1992 (the effective date 
of AD 92-03-03, amendment 39-8157), and thereafter at intervals not 
to exceed 3,000 flight hours, perform the tests, inspections, and 
adjustments described in Boeing Service Bulletin 767-78-0053, dated 
December 13, 1991.
    (1) Following any maintenance action that could affect the 
thrust reverser system, repeat the tests, inspections, and 
adjustments required by paragraph (b) of this AD on the affected 
engine, prior to further flight, in accordance with the service 
bulletin.
    (2) Thereafter, following any maintenance action, continue to 
perform the repetitive tests, inspections, and adjustments required 
by paragraph (b) of this AD on the affected engine at intervals not 
to exceed 3,000 flight hours.
    (c) If any test, inspection, and/or adjustment required by 
paragraph (a) or (b) of this AD cannot be successfully performed, or 
if any test, inspection, and/or adjustment results in findings that 
are unacceptable in accordance with Boeing Service Bulletin 767-78-
0054, dated December 13, 1991, or Boeing Service Bulletin 767-78-
0053, dated December 13, 1991, as applicable, accomplish paragraphs 
(c)(1) and (c)(2) of this AD.
    (1) Prior to further flight, deactivate the associated thrust 
reverser in accordance with Section 78-31-1 of Boeing Document 
D630T002, ``Boeing 767 Dispatch Deviation Guide,'' Revision 9, dated 
May 1, 1991. No more than one thrust reverser on any airplane may be 
deactivated under the provisions of this paragraph.
    (2) Within 10 days after deactivation of any thrust reverser in 
accordance with this paragraph, the thrust reverser must be repaired 
in accordance with Boeing Service Bulletin 767-78-0054, dated 
December 13, 1991, or Boeing Service Bulletin 767-78-0053, dated 
December 13, 1991, as applicable; the tests and/or inspections 
required by paragraph (a) or (b) of this AD must be successfully 
accomplished; and the thrust reverser must then be reactivated.

New Actions Required By This AD:

    (d) Within 5 years after the effective date of this AD, install 
an additional thrust reverser system locking feature (synch-lock 
installation) in accordance with Boeing Service Bulletin 767-78-
0060, Revision 2, dated August 19, 1993 (for Model 767 series 
airplanes equipped with General Electric CF6-80A series engines), or 
Boeing Service Bulletin 767-78-0061, Revision 1, dated August 5, 
1993 (for Model 767 series airplanes equipped with Pratt & Whitney 
JT9D-7R4 series engines), as applicable. Installation of the 
additional thrust reverser system locking feature, as required by 
this paragraph, constitutes terminating action for the requirements 
of paragraphs (a) through (c) of this AD.
    (e) Within 4,000 hours time-in-service after installing the 
synch-lock required by paragraph (d) of this AD (either in 
production or by retrofit), or within 4,000 hours time-in-service 
after the effective date of this AD, whichever occurs later; and 
thereafter at intervals not to exceed 4,000 hours time-in-service: 
Perform functional tests of the synch-lock in accordance with the 
``Thrust Reverser Synch-Lock Test'' procedures specified below. If 
any discrepancy is found during any test, prior to further flight, 
correct it in accordance with procedures described in the Boeing 767 
Maintenance Manual. The airplane may be operated in accordance with 
the provisions and limitations specified in the FAA-approved Master 
Minimum Equipment List (MMEL), provided that no more than one thrust 
reverser on an airplane is inoperative and that no synch-lock on 
that airplane is in an unlocked position.

Thrust Reverser Synch-Lock Test

1. General

    A. There are two thrust reverser synch-locks on each engine. The 
thrust reverser synch-locks are installed on the lower non-locking 
hydraulic actuator of each thrust reverser sleeve.
    B. This task has two parts that must be accomplished:
    (1) The first part does a test of the electrical circuit which 
controls the operation of each thrust reverser synch-lock.
    (2) The second part does a test of the mechanical condition of 
each thrust reverser synch-lock.
    C. The thrust reverser synch-lock is referred to as the ``synch-
lock'' in this procedure.

2. Thrust Reverser Synch-Lock Integrity Test

    A. Equipment
    (1) Multi-meter, Simpson 260 or equivalent--commercially 
available.
    B. Prepare to do the integrity test for the synch-locks.
    (1) Supply electrical power.
    (2) For the left engine, make sure these circuit breakers on the 
overhead circuit breaker panel, P11, are closed:

    (a) L ENG T/R CONT
    (b) L ENG T/R IND
    (c) L ENG T/R SSL CONT

    (3) For the right engine, make sure these circuit breakers on 
the overhead circuit breaker panel, P11, are closed:

    (a) R ENG T/R CONT
    (b) R ENG T/R IND
    (c) R ENG T/R SSL CONT
    (d) AIRPLANES WITH HYDRAULIC MOTOR-DRIVEN GENERATORS (ETOPS): R 
ENG T/R CONT ALTN
    (e) AIRPLANES WITH HYDRAULIC MOTOR-DRIVEN GENERATORS (ETOPS): R 
ENG T/R IND ALTN

    (4) Open the fan cowl panels.
    C. Do the electrical test for the synch-locks.
    (1) Do these steps to make sure there are no ``hot'' short 
circuits in the electrical system which can accidentally supply 
power to the synch-locks:
    (a) Remove the applicable L(R) electrical connectors, 
D20194(D20196), from the L(R) synch-locks, V170(V171).

    Note: You can find the synch-locks attached to the lower non-
locking hydraulic actuators on the applicable thrust reverser 
sleeves.

    (b) Use a multi-meter on the plug end of the applicable 
electrical connector to make sure that these conditions are correct: 


                                                                        
------------------------------------------------------------------------
      From equipment          To equipment             Condition        
------------------------------------------------------------------------
D20194 PIN 1.............  D20194 PIN 2......  -3 TO +1 VDC and         
                                                continuity (less than 5 
                                                OHMS).                  
D20196 PIN 1.............  D20196 PIN 2......  -3 TO +1 VDC and         
                                                continuity (less than 5 
                                                OHMS).                  
------------------------------------------------------------------------

    (c) If you did not find these conditions to be correct, you must 
do these steps:
    (1) Make a careful visual inspection of all the electrical wires 
and connectors between the synch-lock and its applicable power 
circuit breaker.
    (2) Repair all the unserviceable electrical wire and connectors 
that you find.
    (3) Use the multi-meter again to make sure there are no ``hot'' 
short circuits in the electrical system which can accidentally 
supply power to the synch-locks.
    (d) If you find the correct conditions when you use the multi-
meter, continue on and do the mechanical test of the synch-locks.

    Note: Make sure the circuit breakers shown above continue to be 
set to the closed position. Do not install the electrical connectors 
on the synch-locks at this time.

    D. Do the mechanical test for the synch-locks.
    (1) Supply hydraulic power.
    WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE CLEAR OF THE 
AREA BEHIND EACH THRUST REVERSER. IF YOU DO NOT OBEY THIS 
INSTRUCTION, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR IF 
THE SYNCH-LOCKS DO NOT OPERATE CORRECTLY AND THE THRUST REVERSER 
EXTENDS.
    (2) Move the reverse thrust levers for the two engines to try to 
extend the thrust reversers with hydraulic power.

    Note: If the thrust reversers do not extend, the synch-locks are 
serviceable. If the thrust reversers extend, the applicable synch-
locks did not operate correctly.

    (3) Replace the applicable synch-locks on the thrust reverser 
that extended when you moved the reverse thrust levers.
    (4) Make sure the reverse thrust levers are in the fully stowed 
position.
    (5) Install the applicable L(R) electrical connectors, 
D20194(D20196), on the L(R) synch-locks, V170(V171).
    WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE CLEAR OF THE 
AREA BEHIND THE THRUST REVERSERS. IF YOU DO NOT OBEY THIS 
INSTRUCTION, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR 
WHEN THE THRUST REVERSERS ARE EXTENDED.
    (6) Move the reverser thrust levers for the two engines to 
extend the thrust reversers with hydraulic power.

    Note: If the thrust reversers extend, the synch-locks are 
serviceable. If the thrust reversers do not extend, the applicable 
synch-locks did not operate correctly.

    (7) Replace the applicable synch-locks on the thrust reverser 
that did not extend when you moved the reverse thrust levers.
    E. Put the airplane back to its usual condition.
    (1) Move the reverse thrust levers to fully retract the thrust 
reversers on the two engines with hydraulic power.
    (2) Remove the hydraulic power if it is not necessary.
    (3) Remove the electrical power if it is not necessary.
    (4) Close the fan cowl panels.
    (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: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (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.
    (h) The installation shall be done in accordance with Boeing 
Service Bulletin 767-78-0060, Revision 2, dated August 19, 1993; and 
Boeing Service Bulletin 767-78-0061, Revision 1, dated August 5, 
1993; as applicable. 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. Certain other actions shall be done in 
accordance with Boeing Service Bulletin 767-78-0054, dated December 
13, 1991; and Boeing Service Bulletin 767-78-0053, dated December 
13, 1991; as applicable. The incorporation by reference of these 
documents was approved previously by the Director of the Federal 
Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of 
January 27, 1992 (57 FR 3004, January 27, 1992). 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 September 12, 1994.

    Issued in Renton, Washington, on July 28, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-18840 Filed 8-10-94; 8:45 am]
BILLING CODE 4910-13-U