[Federal Register Volume 60, Number 61 (Thursday, March 30, 1995)]
[Proposed Rules]
[Pages 16392-16395]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-7781]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-06-AD]
Airworthiness Directives; Boeing Model 747 SP, SR, -100, -200,
and -300 Series Airplanes Equipped With Pratt & Whitney Model JT9D
Series Engines (Excluding Model JT9D-70 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 SP, SR, -
100, -200, and -300 series airplanes. This proposal would require
repetitive operational tests of the reversible gearbox pneumatic drive
unit (PDU) or the reversing air motor PDU to ensure that the unit can
restrain the thrust reverser sleeve, and correction of any discrepancy
found. This proposal is prompted by the results of an investigation,
which revealed that, in the event of thrust reverser deployment during
high-speed climb or during cruise, these airplanes could experience
control problems. 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 May 24, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-06-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 [[Page 16393]] Airplane Directorate, 1601 Lind Avenue, SW.,
Renton, Washington.
FOR FURTHER INFORMATION CONTACT: G. Michael Collins, Aerospace
Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (206) 227-2689; 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 95-NM-06-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. 95-NM-06-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
In May 1991, a Boeing Model 767 series airplane was involved in an
accident in which a thrust reverser deployed inadvertently during
flight. While the investigation of the accident has not revealed the
cause of that deployment, it has identified a number of possible
failure modes in the thrust reverser control system. Inadvertent
deployment of a thrust reverser during flight could result in reduced
controllability of the airplane.
The FAA and the aviation industry are conducting an in-depth
investigation of the thrust reverser systems installed on various types
of large transport airplanes. In particular, this investigation has
focused on airplane controllability in the event of an in- flight
deployment of a thrust reverser, and thrust reverser reliability in
general. Based on the data gathered from this ongoing investigation,
the FAA issued several airworthiness directives (AD) to require
periodic inspections and tests of the thrust reverser systems on
certain Boeing Model 757 and 767 series airplanes [for example,
reference AD 91-20-09, amendment 39-8043 (56 FR 46725, September 16,
1991) for certain Model 757 series airplanes; and AD 92-24-03,
amendment 39-8408 (57 FR 53258, November 9, 1992) for certain Model 767
series airplanes]. In addition, the FAA has issued or proposed several
AD's to require an additional locking device on thrust reversers that
are installed on Model 737-300/-400/-500, 757, and 767 series airplanes
[for example, reference AD 94-14-02, amendment 39-8954 (59 FR 33646,
June 30, 1994) for certain Model 757 series airplanes; and AD 94-16-03,
amendment 39-8993 (59 FR 41229, August 11, 1994) for certain Model 767
series airplanes]. These actions were taken to enhance the level of
reliability on airplane models that were determined to have
unacceptable flight characteristics following an in-flight deployment
of a thrust reverser.
Until now, the investigation of thrust reverser system reliability
on Boeing Model 747 series airplanes has not been given as high a
priority as the other Boeing models because Model 747 series airplanes
have never experienced control problems as a result of an in-flight
thrust reverser deployment. Based on this long safety record and the
available evidence up to this time, it has been accepted generally that
all Model 747 series airplanes would be shown to be controllable
throughout the flight envelope following an in-flight thrust reverser
deployment.
Boeing has responded to an FAA request for further investigation to
determine the controllability of Model 747 series airplanes following
an in-flight thrust reverser deployment. The investigation results
indicate that Model 747 SP, SR, -100, -200, -300, and -400 series
airplanes could experience certain control problems in the event of a
thrust reverser deployment occurring during high-speed climb or during
cruise.
In light of that information, the FAA determined that certain
inspections and functional tests of the thrust reverser control and
indication system on all Model 747 series airplanes, similar to those
required previously for Model 757 and 767 series airplanes, are
necessary as precautionary actions to provide an acceptable level of
safety for Model 747 series airplanes. Subsequently, on July 13, 1994,
the FAA issued AD 94-15-05, amendment 39-8976 (59 FR 37655, July 25,
1994), to require inspections and functional tests of the thrust
reverser control and indication system on all Model 747-400 series
airplanes.
In the preamble to the notice of AD 94-15-05, the FAA indicated
that it was considering similar rulemaking action for other Model 747
series airplanes. The FAA now has determined that such rulemaking
action is indeed necessary, and this proposed AD follows from that
determination. The FAA has determined that inspections and functional
tests of the thrust reverser control and indication system, similar to
those currently required by AD 94-15-05 for Model 747-400 series
airplanes, are necessary for Model 747 SP, SR, -100, -200, and -300
series airplanes in order to reduce the exposure of these airplanes to
potential undetected single failures in the thrust reverser control
system. The presence of an undetected failure in the thrust reverser
control system, in some cases, can increase the likelihood of an
uncommanded thrust reverser deployment in the event of an additional
thrust reverser control system failure.
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-78A2131, dated September 15, 1994, which describes procedures for
repetitive operational tests of the reversible gearbox pneumatic drive
unit (PDU) or the reversing air motor PDU to ensure that the unit can
restrain the thrust reverser sleeve, and correction of any discrepancy
found. The alert service bulletin recommends that these initial tests
be accomplished no later than 1,300 flight hours after release of the
alert service bulletin. The alert service bulletin also recommends a
repetitive test interval of 2,000 flight hours.
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 require repetitive operational tests of the
reversible gearbox pneumatic drive unit (PDU) or the reversing air
motor PDU to ensure that the unit can restrain the thrust reverser
sleeve, and correction of any discrepancy found during the test. The
actions would be required to be accomplished in accordance with the
[[Page 16394]] alert service bulletin described previously.
In developing appropriate compliance times for the initial test
contained in this proposed AD, the FAA considered the safety
implications and normal maintenance schedules for timely accomplishment
of the proposed actions. In consideration of these items, the FAA
determined that 90 days (for the initial test of the PDU) represents
the maximum interval of time allowable wherein that test can reasonably
be accomplished and an acceptable level of safety can be maintained.
Further, the FAA has determined that the proposed repetitive interval
of 2,000 flight hours is appropriate, based on the service history of
similar components and on an analysis of the system design to predict
the reliability of the system during the service life of the aircraft.
The thrust reverser control and indication system on Model 747-400
series airplanes is similar to the system installed on the airplanes
addressed in this proposed AD. The compliance time for the initial test
proposed in this AD corresponds to that specified in AD 94-15-05 for
Model 747-400 series airplanes. The repetitive test interval specified
in this proposed AD should allow operators to perform the test during
regularly scheduled maintenance.
This proposed AD also would require that operators submit a report
of initial test results to the FAA.
This AD is considered to be interim action until final action is
identified, at which time the FAA may consider additional rulemaking.
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect compliance
with the AD, the owner or operator is required to obtain FAA approval
for an alternative method of compliance with the AD, in accordance with
the paragraph of each AD that provides for such approvals. A note has
been included in this notice to clarify this long-standing requirement.
There are approximately 456 Model 747 SP, SR, -100, -200, and -300
series airplanes of the affected design in the worldwide fleet. The FAA
estimates that 173 airplanes of U.S. registry would be affected by this
proposed AD, that it would take approximately 16 work hours per
airplane to accomplish the proposed actions, and that the average labor
rate is $60 per work hour. Based on these figures, the total cost
impact of the proposed AD on U.S. operators is estimated to be
$166,080, or $960 per airplane.
The total cost impact figure discussed above is 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.
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. 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 adding the following new
airworthiness directive:
Boeing: Docket 95-NM-06-AD.
Applicability: Model 747 SP, SR, -100, -200, and -300 series
airplanes equipped with Pratt & Whitney Model JT9D series engines
(excluding Model JT9D-70 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 use the authority
provided in paragraph (d) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To ensure the integrity of the fail safe features of the thrust
reverser system, accomplish the following:
(a) Within 90 days after the effective date of this AD, perform
an operational test of the reversible gearbox pneumatic drive unit
(PDU) or the reversing air motor PDU to ensure that the unit can
restrain the thrust reverser sleeve, in accordance with Boeing Alert
Service Bulletin 747-78A2131, dated September 15, 1994. Repeat the
test thereafter at intervals not to exceed 2,000 flight hours.
(b) If any of the tests required by this AD cannot be
successfully performed, or if any discrepancy is found during those
tests, accomplish either paragraph (b)(1) or (b)(2) of this AD.
(1) Prior to further flight, correct the discrepancy found, in
accordance with Boeing Alert Service Bulletin 747-78A2131, dated
September 15, 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.
(c) Within 30 days after performing each initial test required
by this AD, submit a report of the test results, both positive and
negative, to the FAA, Seattle Aircraft Certification Office (ACO),
ANM-100S, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; fax
(206) 227-1181. Information collection requirements contained in
this regulation have been approved by the Office of Management and
Budget (OMB) under the provisions of the Paperwork Reduction Act of
1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control
Number 2120-0056.
(d) An alternative method of compliance or adjustment of the
compliance time that [[Page 16395]] 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.
(e) 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 May 24, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-7781 Filed 3-29-95; 8:45 am]
BILLING CODE 4910-13-U
