[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]
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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).
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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]
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