[Federal Register Volume 65, Number 17 (Wednesday, January 26, 2000)]
[Proposed Rules]
[Pages 4179-4182]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-1778]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-67-AD]
RIN 2120-AA64


Airworthiness Directives Boeing Model 747SP, SR, -100, -200, and 
-300 Series Airplanes Equipped with Pratt & Whitney Model JT9D-3, -7, -
7Q, and -7R4G2 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 747SP, 
SR, -100, -200, and -300 series airplanes, that currently requires 
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 action would require installation of a terminating 
modification, and would add repetitive functional tests of that 
installation to detect discrepancies, and repair, if necessary. This 
proposal is prompted by the results of a safety review of the thrust 
reverser systems on Model 747 series airplanes. 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 13, 2000.

ADDRESSES:  Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-67-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:  Larry Reising, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2683; 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-67-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-67-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

[[Page 4180]]

Discussion

    On July 21, 1995, the FAA issued AD 95-16-02, amendment 39-9321 (60 
FR 39631, August 3, 1995), applicable to certain Boeing Model 747SP, 
SR, -100, -200, and -300 series airplanes, to 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. That 
action was 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 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

    In the preamble to AD 95-16-02, the FAA indicated that the actions 
required by that AD were considered ``interim action'' and that further 
rulemaking action was being considered. The FAA now has determined that 
further rulemaking action is indeed necessary, and this proposed AD 
follows from that determination.
    Since the issuance of that AD, the FAA has prioritized the issuance 
of AD's for corrective actions for the thrust reverser system on Boeing 
airplane models following a 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.

Explanation of Relevant Service Information

    The FAA has reviewed and approved the following Boeing Service 
Bulletins:
     747-78-2134, Revision 3, dated March 19, 1998, which 
describes procedures for installation of provisional wiring for the 
additional locking system on the thrust reversers.
     747-78-2052, Revision 5, dated February 22, 1996, which 
describes procedures for removal of the thrust reverser sequencing 
mechanism and installation of a solenoid operated shutoff valve.
    The service bulletins described previously reference the Boeing 
Standard Wiring Practices Manual, which describes wire installation 
procedures, and Boeing 747 Airplane Maintenance Manual (AMM) as 
additional sources of service information for accomplishment of the 
modifications.
     747-78-2152, Revision 1, dated December 12, 1996; Revision 
2, dated December 18, 1997; and Revision 3, dated August 26, 1999, 
which describe procedures for, among other things, installation of the 
following:
    1. Four additional microswitches and associated wiring in the aisle 
stand P8 panel;
    2. New relay panels P252 and P253 and associated wiring;
    3. Left and right wing/body disconnect panels, engine struts, and 
associated wiring;
    4. Four circuit breakers and associated wiring changes in the P6 
and P8 panels; and
    5. Sync lock and associated wiring on each thrust reverser.
    Accomplishment of Boeing Service Bulletin 747-78-2152, Revision 1, 
Revision 2, or Revision 3, requires prior or concurrent accomplishment 
of Boeing Service Bulletins 747-78-2134, Revision 3, and 747-78-2052, 
Revision 5. Accomplishment of these actions would eliminate the need 
for certain repetitive tests.
    The modification procedures described by Boeing Service Bulletins 
747-78-2152 and 747-78-2134 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 747-78-2152, 
Revision 1, Revision 2, and Revision 3, and 747-78-2134, Revision 3, 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, the 
proposed AD would supersede AD 95-16-02 to continue to 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 proposed AD would require installation of a modification, 
and would add 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 (also called a sync lock) on each thrust reverser 
would be required to be accomplished in accordance with the procedures 
described in the Boeing 747 Airplane Maintenance Manual (AMM). 
Correction of any discrepancy detected would be required to be 
accomplished in accordance with the AMM.

Differences Between Service Bulletins and This Proposed AD

    Operators should note that, although Boeing Service Bulletin 747-
78-2152, Revision 1, Revision 2, and Revision 3 recommend no specific 
compliance time for accomplishment of the additional 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

[[Page 4181]]

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 repetitive functional testing of the additional lock 
installation following accomplishment of that installation, the FAA has 
determined that repetitive functional tests of the additional lock 
installation on each thrust reverser, at intervals not to exceed 3,000 
flight hours, will support continued operational safety of thrust 
reversers with actuation system locks.

Cost Impact

    There are approximately 457 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 220 airplanes of U.S. registry 
would be affected by this proposed AD.
    The operational tests that are currently required by AD 95-16-02, 
and retained in this AD, take approximately 16 work hours (4 per 
engine) 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 $211,200, or $960 
per airplane, per test cycle.
    It would take approximately 544 work hours per airplane, to 
accomplish the proposed wiring modifications, 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 wiring modifications proposed by this AD on U.S. 
operators is estimated to be $7,180,800, or $32,640 per airplane.
    It would take approximately 104 work hours (26 per engine) per 
airplane, to accomplish the proposed removal of the thrust reverser 
sequencing mechanism and installation of a solenoid operated shutoff 
valve, 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 removal and installation 
proposed by this AD on U.S. operators is estimated to be $1,372,800, or 
$6,240 per airplane.
    It would take approximately 568 work hours per airplane, to 
accomplish the proposed sync lock hardware 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 $7,497,600, or $34,080 per airplane.
    The functional tests proposed in this AD would take approximately 8 
work hours (2 hours per engine) per airplane to accomplish, 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 $105,600, or $480 per airplane, per test 
cycle.
    The cost impact figures discussed above are 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 39-9321 (60 FR 
39631, August 3, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 99-NM-67-AD. Supersedes AD 95-16-02, amendment 39-
9321.

    Applicability: Model 747SP, SR, -100, -200, and -300 series 
airplanes equipped with Pratt & Whitney Model JT9D-3, -7, -7Q, and -
7R4G2 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 (e)(1) 
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 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 95-16-02

Operational Test

    (a) Within 90 days after September 5, 1995 (the effective date 
of AD 95-16-02, amendment 39-9321), 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 until accomplishment of 
paragraph (c) of this AD.

Corrective Action

    (b) If any of the tests required by paragraph (a) of 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 any 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.

[[Page 4182]]

New Requirements of This AD

Modifications

    (c) Within 36 months after the effective date of this AD, 
accomplish the requirements of paragraphs (c)(1), (c)(2), and (c)(3) 
of this AD. Accomplishment of the actions required by this paragraph 
constitutes terminating action for the repetitive tests required by 
paragraph (a) of this AD.
    (1) Install an additional locking system on each thrust reverser 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-78-2152, Revision 1, dated December 12, 1996; Revision 
2, dated December 18, 1997; or Revision 3, dated August 26, 1999.
    (2) Remove the thrust reverser sequencing mechanism and install 
a solenoid operated shutoff valve in accordance with Boeing Service 
Bulletin 747-78-2052, Revision 5, dated February 22, 1996.
    (3) Install provisional wiring for the additional locking system 
on the thrust reversers, in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-78-2134, Revision 3, 
dated March 19, 1998.

Repetitive Tests

    (d) Within 3,000 flight hours after accomplishment of paragraph 
(c) of this AD: Perform a functional test to detect discrepancies of 
the additional locking system on each thrust reverser in accordance 
with the procedures described in the Boeing 747 Airplane Maintenance 
Manual (AMM), Section 78-34-11, dated October 25, 1997. Prior to 
further flight, correct any discrepancy detected and repeat the 
functional test of that repair in accordance with the procedures 
described in the AMM. Repeat the functional tests thereafter at 
intervals not to exceed 3,000 flight hours.

Alternative Methods of Compliance

    (e)(1) 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.
    (2) Alternative methods of compliance, approved previously in 
accordance with paragraphs (a) and (b) of AD 95-16-02, amendment 39-
9321, are approved as alternative methods of compliance with the 
corresponding paragraphs in this AD.

    Note 2:  Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (f) 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 20, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-1778 Filed 1-25-00; 8:45 am]
BILLING CODE 4910-13-U