[Federal Register Volume 59, Number 22 (Wednesday, February 2, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2334]


[[Page Unknown]]

[Federal Register: February 2, 1994]


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


DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-178-AD]

 

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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 767 
series airplanes, that currently requires inspections, adjustments, and 
functional checks of the thrust reverser system. This action would add 
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 
proposal 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 the proposed AD are intended to prevent possible 
discrepancies in the thrust reverser control system that can result in 
the inadvertent deployment of a thrust reverser during flight.

DATES: Comments must be received by March 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 93-NM-178-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.
    The service information referenced in the proposed rule 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.

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:

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 notice may be changed in 
light of the comments received.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-NM-178-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-103, Attention: Rules 
Docket No. 93-NM-178-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 7, 1992, the FAA issued AD 92-03-03, Amendment 39-8157 
(57 FR 3004, January 27, 1992), applicable to certain Boeing Model 767 
series airplanes, to require inspections, adjustments, and functional 
checks of the thrust reverser system. That action was prompted by an 
ongoing design review, resulting from an accident investigation from 
which it has been determined that, prior to the accident, the airplane 
apparently experienced an uncommanded in-flight deployment of a thrust 
reverser. Deployment of a thrust reverser during flight could result in 
reduced controllability of the airplane. The requirements of that AD 
are intended to ensure the integrity of the fail safe features of the 
thrust reverser system by preventing the possible discrepancies in the 
thrust reverser control system that can result in the inadvertent 
deployment of a thrust reverser during flight.
    Since the issuance of that AD, Boeing has developed a modification 
for Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 
or General Electric CF6-80A series engines, which, when accomplished, 
will ensure that the level of safety inherent in the original type 
design of the thrust reverser system is further enhanced. The FAA has 
determined that the installation of these additional features will 
further reduce the likelihood of an in-flight thrust reverser 
deployment.
    The FAA has reviewed and approved 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), and Boeing 
Service Bulletin 767-78-0061, Revision 1, dated August 5, 1993 (for 
Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 
series engines). These service bulletins describe procedures for 
installation of an additional thrust reverser system locking feature 
(denoted as a ``synch-lock''), which will reduce the possibility of an 
uncommanded in-flight deployment of the thrust reversers. 
Accomplishment of that installation includes revising certain wiring, 
replacing selected circuit breakers, changing the microswitch pack, and 
adding electrical components. The synch-lock is controlled 
independently of the existing electro-mechanical safety features of the 
thrust reverser system. This additional locking feature has been 
certified by the FAA. The FAA has determined that installation of the 
synch-lock in accordance with the applicable service bulletin is 
necessary in order to positively address the identified unsafe 
condition with regard to these airplanes.
    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 92-03-03 to continue to require 
repetitive inspections, adjustments, and functional checks of the 
thrust reverser system. This action would add a requirement for 
installation of an additional thrust reverser system locking feature 
(synch-lock). Installation of the synch-lock would terminate the 
requirement for repetitive inspections, adjustments, and functional 
checks of the thrust reverser system. The synch-lock installation would 
be required to be accomplished in accordance with the service bulletin 
described previously.
    This AD would also add periodic functional tests of the synch-lock 
following its installation, and repair of any discrepancy found. The 
FAA has determined that these tests are necessary to ensure the 
integrity of the synch-lock installation and that it is effective in 
preventing the identified unsafe condition. This determination is based 
on the fact that the synch-lock is a new design and its reliability has 
not been adequately proven through service experience. Boeing has 
submitted to the FAA procedures for accomplishment of the synch-lock 
integrity test described in the airplane maintenance manual. These 
procedures are accomplished independently of other thrust reverser 
system tests.
    Since only limited information is available currently to 
substantiate the in-service reliability of the synch-lock device, the 
FAA has established an appropriate functional test interval of 1,000 
hours time-in-service.
    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 of these airplanes of 
U.S. registry would be affected by this proposed AD. The inspections, 
adjustments, and functional checks required currently by AD 92-03-03 
require approximately 16 work hours per airplane to accomplish, at an 
average labor rate of $55 per work hour. Based on these figures, the 
total cost impact of that action 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 
would take approximately 786 work hours per airplane to accomplish the 
modification proposed by this AD, and 1 work hour to accomplish the 
proposed functional tests, at an average labor rate of $55 per work 
hour. Required parts would be supplied by the manufacturer at no cost 
to operators. Based on these figures, the total cost impact of the 
proposed AD 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 and Whitney JT9D-7R4 series engines of the affected design in the 
worldwide fleet. The FAA estimates that 30 of these airplanes of U.S. 
registry would be affected by this proposed AD. The inspections, 
adjustments, and functional checks required currently by AD 92-03-03 
require approximately 16 work hours per airplane to accomplish, at an 
average labor rate of $55 per work hour. Based on these figures, the 
total cost impact of that action on U.S. operators of Model 767 series 
airplanes equipped with Pratt and 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 and Whitney JT9D-7R4 series engines, the FAA estimates that it 
would take approximately 812 work hours per airplane to accomplish the 
proposed modification, and 1 work hour to accomplish the proposed 
functional tests, at an average labor rate of $55 per work hour. 
Required parts would be supplied by the manufacturer at no cost to 
operators. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators of Model 767 series airplanes equipped 
with Pratt and Whitney JT9D-7R4 series engines is estimated to be 
$1,341,450, or $44,715 per airplane.
    These total cost figures assume that no operator has yet 
accomplished the proposed requirements of this AD action.
    The number of required work hours for accomplishing the proposed 
functional tests, as indicated above, is presented as if the 
accomplishment of those tests proposed in this AD were to be conducted 
as ``stand alone'' actions. However, in actual practice, those tests 
for the most part would 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 would 
be minimal in many instances. Additionally, any costs associated with 
special airplane scheduling would be minimal.
    The FAA recognizes that the proposed modification would require a 
large number of work hours to accomplish. However, the 5-year 
compliance time specified in paragraph (d) of this proposed 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 proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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 
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 14 
CFR part 39 of the Federal Aviation Regulations 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), to read as follows:


Boeing: Docket 93-NM-178-AD. Supersedes AD 92-03-03, Amendment 39-
8157.

    Applicability: Model 767 series airplanes equipped with Pratt 
and 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 and Whitney JT9D-7R4 
series engines: Within 60 days after the effective date of this AD, 
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 the effective date of this AD, 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 2, dated August 5, 
1993 (for Model 767 series airplanes equipped with Pratt and 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 1,000 hours time-in-service after installing the 
synch-lock required by paragraph (d) of this AD (either in 
production or by retrofit), or within 1,000 hours time-in-service 
after the effective date of this AD, whichever occurs later; and 
thereafter at intervals not to exceed 1,000 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.

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 FAR 
21.197 and 21.199 to operate the airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Renton, Washington, on January 27, 1994.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-2334 Filed 2-1-94; 8:45 am]
BILLING CODE 4910-13-P