[Federal Register Volume 64, Number 248 (Tuesday, December 28, 1999)]
[Proposed Rules]
[Pages 72579-72582]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-33569]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-66-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-400 Series Airplanes
Equipped With Pratt & Whitney PW4000 Series Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Boeing Model 747-400
series airplanes. This proposal would require installation of a
modification of the thrust reverser control and indication system and
wiring on each engine; and repetitive functional tests of that
installation to detect discrepancies, and repair, if necessary. This
proposal is prompted by the results of a safety review, which revealed
that in-flight deployment of a thrust reverser could result in a
significant reduction in airplane controllability. The actions
specified by the proposed AD are intended to ensure the integrity of
the fail-safe features of the thrust reverser system by preventing
possible failure modes, which could result in inadvertent deployment of
a thrust reverser during flight, and consequent reduced controllability
of the airplane.
DATES: Comments must be received by February 11, 2000.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-66-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 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: Dorr Anderson, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2684; 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 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 99-NM-66-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. 99-NM-66-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On May 26, 1991, a Boeing Model 767-300ER series airplane was
involved in an accident as a result of an uncommanded in-flight
deployment of a thrust reverser. Following that accident, a study was
conducted to evaluate the potential effects of an uncommanded thrust
reverser deployment throughout the flight regime of the Boeing Model
[[Page 72580]]
747 series airplane. The study included a re-evaluation of the thrust
reverser control system fault analysis and airplane controllability.
The results of the evaluation indicated that, in the event of thrust
reverser deployment during high-speed climb using high engine power,
these airplanes also could experience control problems. This condition,
if not corrected, could result in possible failure modes in the thrust
reverser control system, inadvertent deployment of a thrust reverser
during flight, and consequent reduced controllability of the airplane.
The FAA has prioritized the issuance of AD's for corrective actions
for the thrust reverser system on Boeing airplane models following the
1991 accident. 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.
AD's correcting the same type of unsafe condition addressed by this AD
have been previously issued for specific airplanes within the Boeing
Model 737, 757 and 767 series.
Service experience has shown that in-flight thrust reverser
deployments have occurred on Model 747 airplanes during certain flight
conditions with no significant airplane controllability problems being
reported. However, the manufacturer has been unable to establish that
acceptable airplane controllability would be achieved following these
deployments throughout the operating envelope of the airplane.
Additionally, safety analyses performed by the manufacturer and
reviewed by the FAA, has been unable to establish that the risks for
uncommanded thrust reverser deployment during critical flight
conditions is acceptably low.
Other Relevant Rulemaking
This proposed AD is related to AD 94-15-05, amendment 39-8976 (59
FR 37655, July 25, 1994), which is applicable to all Boeing Model 747-
400 series airplanes, and requires various inspections and tests of the
thrust reverser control and indication system, and correction of any
discrepancy found. Accomplishment of the actions proposed in this AD
would terminate certain inspections and tests required by AD 94-15-05.
Explanation of Relevant Service Information
The FAA has reviewed and approved the following Boeing Service
Bulletins:
747-78-2155, Revision 2, dated November 5, 1998, which
describes procedures for installation of an additional locking system
on the thrust reversers;
747-45-2016, Revision 1, dated May 2, 1996, which
describes procedures for modifications to the central maintenance
computer system hardware and software;
747-31-2245, dated June 27, 1996, which describes
procedures for modifications of the integrated display system software;
and
747-78-2154, Revision 3, dated December 11, 1997, which
describes procedures for the installation of provisional wiring for an
additional thrust reverser locking device. This service bulletin
references the Boeing Standard Wiring Practices Manual, which describes
wire installation and separation procedures.
Accomplishment of Boeing Service Bulletin 747-78-2155, Revision 2,
requires prior or concurrent accomplishment of Boeing Service Bulletins
747-45-2016, Revision 1, 747-31-2245; and 747-78-2154, Revision 3.
Accomplishment of these actions would eliminate the need for certain
repetitive inspections and tests.
The modification procedures described by Boeing Service Bulletins
747-78-2154 and 747-78-2155 were previously validated by the
manufacturer, and the necessary changes have been incorporated into the
latest revisions of the service bulletins. The FAA has determined that
the procedures specified in Boeing Service Bulletins 747-78-2154,
Revision 3, and 747-78-2155, Revision 2, as well as the other service
bulletins referenced in this proposed AD, have been effectively
validated and therefore proposes that this modification be required.
Several airplanes have been successfully modified in accordance with
the service bulletins, and this past experience should minimize the
likelihood for subsequent service bulletin revisions, requests for
alternative methods of compliance, and superseding AD's.
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, this
proposed AD would require installation of a modification of the thrust
reverser control and indication system and wiring on each engine; and
repetitive functional tests of that installation to detect
discrepancies, and repair, if necessary. The actions would be required
to be accomplished in accordance with the service bulletins described
previously, except as discussed below.
Repetitive functional tests to detect discrepancies of the
actuation system lock on each thrust reverser would be required to be
accomplished in accordance with the procedure included in Appendix 1 of
this AD. Correction of any discrepancy detected would be required to be
accomplished in accordance with the procedures described in the Boeing
747 Airplane Maintenance Manual.
Differences Between Service Bulletin and This Proposed AD
Operators should note that, although Boeing Service Bulletin 747-
78-2155, Revision 2, does not recommend a specific compliance time for
accomplishment of the actuation system lock installation, the FAA has
determined that an unspecified compliance time would not address the
identified unsafe condition in a timely manner. In developing an
appropriate compliance time for this AD, the FAA considered not only
the manufacturer's recommendation, but the degree of urgency associated
with addressing the subject unsafe condition, the average utilization
of the affected fleet, and the time necessary to perform the
installation. In light of all of these factors, the FAA finds a 36-
month compliance time for completing the required actions to be
warranted, in that it represents an appropriate interval of time
allowable for affected airplanes to continue to operate without
compromising safety.
Operators also should note that, although the service bulletin does
not specify functional testing of the actuation system lock
installation following accomplishment of that installation, the FAA has
determined that repetitive functional tests of the actuation system
lock on each thrust reverser will support continued operational safety
of thrust reversers with actuation system locks.
Cost Impact
There are approximately 177 Model 747-400 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 53
airplanes of U.S. registry would be affected by this proposed AD.
For airplanes identified in Boeing Service Bulletin 747-78-2155,
Revision 2, (45 airplanes) it would take approximately 510 work hours
per
[[Page 72581]]
airplane, to accomplish the proposed installation, at an average labor
rate of $60 per work hour. Required parts would be provided by the
manufacturer at no cost to the operators. Based on these figures, the
cost impact of the installation proposed by this AD on U.S. operators
is estimated to be $1,377,000, or $30,600 per airplane.
For all airplanes (53 airplanes) it would take approximately 2 work
hours per airplane, to accomplish the proposed functional test, at an
average labor rate of $60 per work hour. Based on these figures, the
cost impact of the functional test proposed by this AD on U.S.
operators is estimated to be $6,360, or $120 per airplane, per test
cycle.
The cost impact figures discussed below refer to actions in other
service bulletins for the airplanes identified in Boeing Service
Bulletin 747-78-2155, Revision 2 (affects 45 U.S.-registered
airplanes), that must be accomplished prior to or concurrent with the
installation specified in Boeing Service Bulletin 747-78-2155, Revision
2.
It would take approximately 3 work hours per airplane to accomplish
the central maintenance computer system modification, at an average
labor rate of $60 per work hour. Required parts would be provided by
the manufacturer at no cost to the operators. Based on these figures,
the cost impact of the modification is estimated to be $8,100, or $180
per airplane.
It would take approximately 2 work hours per airplane to accomplish
the changes to the integrated display system, at an average labor rate
of $60 per work hour. Required parts would be provided by the
manufacturer at no cost to the operators. Based on these figures, the
cost impact of the modification is estimated to be $5,400, or $120 per
airplane.
It would take approximately 346 work hours per airplane to
accomplish wiring provisions for the thrust reverser sync locks, at an
average labor rate of $60 per work hour. Required parts would be
provided by the manufacturer at no cost to the operators. Based on
these figures, the cost impact of the modification is estimated to be
$934,200, or $20,760 per airplane.
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 AD were not adopted.
Regulatory Impact
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
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 adding the following new
airworthiness directive:
Boeing: Docket 99-NM-66-AD.
Applicability: Model 747-400 series airplanes equipped with
Pratt & Whitney PW4000 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 (c) 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 inadvertent deployment of a thrust reverser during
flight and consequent reduced controllability of the airplane,
accomplish the following:
Modifications
(a) For airplanes identified in Boeing Service Bulletin 747-78-
2155, Revision 2, dated November 5, 1998: Accomplish the
requirements of paragraphs (a)(1) and (a)(2) of this AD at the times
specified in those paragraphs. Accomplishment of these actions
constitutes terminating action for the inspections and tests
required by paragraph (a) of AD 94-15-05, amendment 39-8976.
(1) Within 36 months after the effective date of this AD:
Install an additional locking system on each engine thrust reverser
in accordance with the Accomplishment Instructions of Boeing Service
Bulletin 747-78-2155, Revision 2, dated November 5, 1998.
(2) Prior to or concurrent with the installation required by
paragraph (a)(1) of this AD, accomplish the requirements of
paragraphs (a)(2)(i), (a)(2)(ii), and (a)(2)(iii) of this AD:
(i) Modify the central maintenance computer system hardware and
software in accordance with Boeing Service Bulletin 747-45-2016,
Revision 1, dated May 2, 1996.
(ii) Modify the integrated display system software in accordance
with Boeing Service Bulletin 747-31-2245, dated June 27, 1996.
(iii) Install the provisional wiring for the locking system on
the thrust reversers in accordance with Boeing Service Bulletin 747-
78-2154, Revision 3, dated December 11, 1997.
Repetitive Functional Tests
(b) Within 4,000 hours time-in-service after accomplishment of
paragraph (a) of this AD, or production equivalent; or within 1,000
hours time-in-service after the effective date of this AD, whichever
occurs later: Perform a functional test to detect discrepancies of
the additional locking system on each engine thrust reverser, in
accordance with Appendix 1 of this AD. Prior to further flight,
correct any discrepancy detected and repeat the functional test of
that repair, in accordance with the procedures described in the
Boeing 747 Airplane Maintenance Manual. Repeat the functional test
thereafter at intervals not to exceed 4,000 hours time-in-service.
Alternative Methods of Compliance
(c) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
[[Page 72582]]
Special Flight Permit
(d) 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 Reverse Sync-Lock--Adjustment/Test
1. General.
A. There are two sync-locks for each engine thrust reverser. The
sync-lock is installed on the lower non-locking hydraulic actuator
of each thrust reverser sleeve.
B. The Thrust Reverser Sync-Lock Integrity Test has two tasks:
(1) The first task does a test of the electrical circuit which
controls the operation of the sync-lock on each thrust reverser
sleeve.
(2) The second task does a test of the mechanical function of
the sync-lock on each thrust reverser sleeve.
C. The thrust reverser sync-lock is referred to as ``the sync-
lock'' in this procedure.
2. Thrust Reverser Sync-Lock Integrity Test.
A. Equipment--Multi-meter, Simpson 260 or equivalent--
commercially available
B. Prepare to do the integrity test for the sync-locks
(1) Supply electrical power
(2) For the applicable engine, make sure these circuit breakers
on the Main Power Distribution Panel P6, are closed:
6F12 ENG 1 T/R IND
6E12 ENG 2 T/R IND
6D12 ENG 3 T/R IND
6C12 ENG 4 T/R IND
6F13 ENG 1 T/R CONT
6E13 ENG 2 T/R CONT
6D13 ENG 3 T/R CONT
6C13 ENG 4 T/R CONT
6F11 ENG 1 T/R LOCK CONT
6E11 ENG 2 T/R LOCK CONT
6D11 ENG 3 T/R LOCK CONT
6C11 ENG 4 T/R LOCK CONT
(3) Open the fan cowl panels for the applicable engine.
C. Do the electrical integrity test for the sync-locks.
(1) Do these steps, for the applicable engine, to make sure
there are no ``hot'' short circuits in the electrical system which
can accidentally supply power to the sync-locks:
(a) Remove the electrical connector, D20194, from the sync-lock,
V170, on the left sleeve of the thrust reverser.
(b) Remove the electrical connector, D20196, from the sync-lock,
V171, on the right sleeve of the thrust reverser.
(c) Use a multi-meter on the plug end of the applicable
electrical connector to make sure that these conditions are correct:
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 (than 5
ohms)
(d) If you find the correct conditions, do the mechanical
integrity test for the sync-locks.
(e) 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 sync-lock and its power circuit.
(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 sync-locks.
D. Do the mechanical integrity test for the sync-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 SYNC-LOCKS DO NOT OPERATE CORRECTLY AND THE THRUST REVERSER
EXTENDS.
(2) Move the applicable reverser thrust lever aft to try to
extend the thrust reverser with hydraulic power.
Note: If the thrust reverser sleeves do not extend, the sync-
locks are serviceable. If the thrust reverser sleeves extend, the
applicable sync-lock did not operate correctly.
(3) Replace the sync-lock(s) on the thrust reverser sleeve(s)
that did extend when you moved the reverse thrust levers. Repeat
steps 2.D.(1) and 2.D.(2) to verify that functional sync-locks are
installed.
(4) Move the applicable thrust reverser lever forward to the
stow position.
(5) Install the electrical connector, D20194, on the sync-lock,
V170 on the left sleeve of the thrust reverser.
(6) Install the electrical connector, D20196, on the sync-lock,
V171, on the right sleeve of the thrust reverser.
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
WHEN THE THRUST REVERSERS ARE EXTENDED.
(7) Move the applicable thrust reverser aft to try to extend the
thrust reverser with hydraulic power.
Note: If the thrust reverser sleeves extended, the sync-locks
are serviceable. If the thrust reverser sleeves did not extend, the
applicable sync-lock is not serviceable.
(8) Replace the sync-lock(s) on the thrust reverser sleeve that
did not extend when you moved the reverse thrust levers. Repeat
steps 2.D.(4) through 2.D.(7) to verify that functional sync-locks
are installed.
(9) Repeat steps 2.A. through 2.D. for all other engine
positions.
E. Put the airplane back to its usual condition.
(1) Move the reverse thrust levers forward to fully retract the
thrust reversers on the applicable engine.
(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.
Issued in Renton, Washington, on December 21, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-33569 Filed 12-27-99; 8:45 am]
BILLING CODE 4910-13-U
