[Federal Register Volume 64, Number 13 (Thursday, January 21, 1999)]
[Proposed Rules]
[Pages 3226-3228]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-1307]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 64, No. 13 / Thursday, January 21, 1999 /
Proposed Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-247-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-200 and -300 Series
Airplanes Equipped With General Electric CF6-80C2 Series Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Boeing Model 747-
200 and -300 series airplanes, that currently requires various
inspections and functional tests to detect discrepancies of the thrust
reverser control and indication system, and correction of any
discrepancy found. This action would reduce the repetitive interval for
one certain functional test. This proposal is prompted by reports
indicating that several center drive units (CDU) were returned to the
manufacturer of the CDU's because of low holding torque of the CDU cone
brake. 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 in the thrust reverser control
system that can result in inadvertent deployment of a thrust reverser
during flight.
DATES: Comments must be received by March 8, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-247-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: Holly Thorson, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-1357; 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 98-NM-247-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. 98-NM-247-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On March 3, 1995, the FAA issued AD 95-06-01, amendment 39-9171 (60
FR 13623, March 14, 1995), applicable to certain Boeing Model 747-200
and -300 series airplanes, to require various inspections and
functional tests of the thrust reverser control and indication system,
and correction of any discrepancy found. That action was prompted by an
investigation to determine the controllability of Model 747 series
airplanes following an in-flight thrust reverser deployment, which
revealed that, in the event of thrust reverser deployment during high-
speed climb or during cruise, these airplanes could experience control
problems. The requirements of that AD are intended to ensure the
integrity of the fail safe features of the thrust reverser system by
preventing possible failure modes in the thrust reverser control system
that can result in inadvertent deployment of a thrust reverser during
flight.
Actions Since Issuance of Previous Rule
Since the issuance of that AD, the FAA has received reports
indicating that several thrust reverser center drive units (CDU) were
returned to the manufacturer of the CDU's because of low holding torque
of the CDU cone brake. This possible failure condition was not included
in any previous safety assessment of the thrust reverser by the
manufacturer. The returned CDU's had accumulated between 3,400 and
3,600 total flight hours. The cause of the low holding torque is a
combination of cone brake wear, overrunning clutch wear, and grease
contamination of the cone brake. Such a low torque condition could
result in failure of the cone brake of the CDU, which could disable one
of the fail safe features of the thrust reverser system that prevent
deployment of a thrust reverser during flight.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 747-
78A2166, Revision 1, dated October 9, 1997, which describes procedures
for a functional test of the CDU cone brake on each thrust reverser.
The procedures for the functional test of the cone brake are
substantially similar to those described
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in Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994 (which
was referenced as the appropriate source of service information in AD
95-06-01). However, Boeing Service Bulletin 747-78A2166, Revision 1,
specifies a shorter repetitive interval for the functional test (650
flight hours) than was specified in Boeing Alert Service Bulletin 747-
78A2130 (1,300 flight hours).
The FAA previously reviewed and approved Boeing Alert Service
Bulletin 747-78A2130, dated May 26, 1994, which describes procedures
for various inspections and functional tests of the thrust reverser
control and indication system (including a functional test of the CDU
cone brake), and correction of any discrepancy found.
Accomplishment of the actions specified in the service bulletins is
intended to adequately address the identified unsafe condition.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would supersede AD 95-06-01 to continue to require various
inspections and functional tests to detect discrepancies of the thrust
reverser control and indication system, and correction of any
discrepancy found. This proposed AD would reduce the repetitive
interval for the functional test of the CDU cone brake. The actions
would be required to be accomplished in accordance with the service
bulletins described previously, except as discussed below.
Difference Between Latest Service Bulletin and This Proposed AD
Operators should note that Boeing Service Bulletin 747-78A2166,
Revision 1, specifies that the functional test of the CDU cone brake
described in that service bulletin is not necessary for Model 747-200
and -300 series airplanes that are equipped with thrust reversers
modified in accordance with Boeing Service Bulletin 747-78-2144 (or
production equivalent). Boeing Model 747-200 and -300 series airplanes
having line numbers 1061 and higher are equipped with such modified
thrust reversers; therefore, the effectivity listing of Boeing Service
Bulletin 747-78A2166, Revision 1, includes only Model 747 series
airplanes equipped with General Electric Model CF6-80C2 engines having
line numbers 679 through 1060 inclusive.
This AD, however, would require that the cone brake functional test
be performed on Model 747-200 and -300 series airplanes equipped with
General Electric Model CF6-80C2 engines regardless of whether they are
equipped with thrust reversers modified in accordance with Boeing
Service Bulletin 747-78-2144. The FAA has determined that an inspection
interval of 1,000 hours time-in-service (which was required by AD 95-
06-01) does not provide a sufficient level of safety for either the
modified or unmodified thrust reversers, given the low holding torque
condition that has been identified for the CDU cone brake.
Interim Action
This is considered to be interim action. The manufacturer has
advised that it currently is developing a modification that will
positively address the unsafe condition addressed by this AD. Once this
modification is developed, approved, and available, the FAA may
consider additional rulemaking.
Cost Impact
There are approximately 9 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry
would be affected by this proposed AD.
The actions proposed by this AD would not add any additional
economic burden on affected operators, other than the costs that are
associated with repeating the functional test of the cone brake at
reduced intervals (at intervals not to exceed 650 hours time-in-service
rather than at intervals not to exceed 1,000 hours time-in-service).
The current costs associated with AD 95-06-01 are reiterated in their
entirety (as follows) for the convenience of affected operators.
The actions that are currently required by AD 95-06-01, and
retained in this AD, take approximately 33 work hours per airplane to
accomplish, at an average labor rate of $60 per work hour. Based on
these figures, the cost impact of the currently required actions on
U.S. operators is estimated to be $3,960, or $1,980 per airplane, per
inspection/test cycle.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the current or 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 removing amendment 39-9171 (60 FR
13623, March 14, 1995), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 98-NM-247-AD. Supersedes AD 95-06-01, Amendment 39-
9171.
Applicability: Model 747-200 and -300 series airplanes equipped
with General Electric Model CF6-80C2 series engines with Power
Management Control engine controls, 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 (f) of
this AD. The request should include an assessment of the
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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 ensure the integrity of the fail safe features of the thrust
reverser system by preventing possible failure modes in the thrust
reverser control system that can result in inadvertent deployment of
a thrust reverser during flight, accomplish the following:
Restatement of Requirements of AD 95-06-01
(a) Within 90 days after April 13, 1995 (the effective date AD
95-06-01, amendment 39-9171), perform tests of the position switch
module and the cone brake of the center drive unit (CDU) on each
thrust reverser, and perform an inspection to detect damage to the
bullnose seal on the translating sleeve on each thrust reverser, in
accordance with paragraphs III.A. through III.C. of the
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
78A2130, dated May 26, 1994. Repeat the tests and inspection
thereafter at intervals not to exceed 1,000 hours time-in-service
until the functional test required by paragraph (d) of this AD is
accomplished.
(b) Within 9 months after April 13, 1995, perform inspections
and functional tests of the thrust reverser control and indication
system in accordance with paragraphs III.D. through III.F., III.H.,
and III.I. of the Accomplishment Instructions of Boeing Alert
Service Bulletin 747-78A2130, dated May 26, 1994. Repeat these
inspections and functional tests thereafter at intervals not to
exceed 18 months.
(c) If any of the inspections and/or functional tests required
by paragraphs (a) and (b) of this AD cannot be successfully
performed, or if any discrepancy is found during those inspections
and/or functional tests, accomplish either paragraph (c)(1) or
(c)(2) of this AD.
(1) Prior to further flight, correct the discrepancy found, in
accordance with Boeing Alert Service Bulletin 747-78A2130, dated May
26, 1994. Or
(2) The airplane may be operated in accordance with the
provisions and limitations specified in an operator's FAA-approved
Minimum Equipment List (MEL), provided that no more than one thrust
reverser on the airplane is inoperative.
New Requirements of This AD
(d) Within 1,000 hours time-in-service after the most recent
test of the CDU cone brake performed in accordance with paragraph
(a) of this AD, or within 650 hours time-in-service after the
effective date of this AD, whichever occurs first: Perform a
functional test to detect discrepancies of the CDU cone brake on
each thrust reverser, in accordance with Boeing Service Bulletin
747-78A2166, Revision 1, dated October 9, 1997, or paragraph III.B.
of the Accomplishment Instructions of Boeing Alert Service Bulletin
747-78A2130, dated May 26, 1994. Repeat the functional test
thereafter at intervals not to exceed 650 hours time-in-service.
Accomplishment of such functional test constitutes terminating
action for the repetitive test of the CDU cone brake required by
paragraph (a) of this AD.
(e) If any functional test required by paragraph (d) of this AD
cannot be successfully performed, or if any discrepancy is found
during any functional test required by paragraph (d) of this AD,
accomplish either paragraph (e)(1) or (e)(2) of this AD.
(1) Prior to further flight, correct the discrepancy found, in
accordance with Boeing Service Bulletin 747-78A2166, Revision 1,
dated October 9, 1997, or paragraph III.B. of the Accomplishment
Instructions of Boeing Alert Service Bulletin 747-78A2130, dated May
26, 1994. Or
(2) The airplane may be operated in accordance with the
provisions and limitations specified in the operator's FAA-approved
MEL, provided that no more than one thrust reverser on the airplane
is inoperative.
(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 2: 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.
Issued in Renton, Washington, on January 14, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-1307 Filed 1-20-99; 8:45 am]
BILLING CODE 4910-13-P