[Federal Register Volume 62, Number 71 (Monday, April 14, 1997)]
[Proposed Rules]
[Pages 18063-18065]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-9453]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-13-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-400 Series Airplanes
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 replacing the cam
assembly, cam bellcrank assembly, and thrust reverser control switch
actuator on all four thrust levers with new components. This proposal
is prompted by a report of an uncommanded automatic retraction of the
leading edge flaps during takeoff. The actions specified by the
proposed AD are intended to prevent such uncommanded automatic
retraction, which could seriously degrade liftoff and climb
capabilities, and result in near-stall conditions at a critical phase
of the flight.
DATES: Comments must be received by May 22, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 97-NM-13-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this
[[Page 18064]]
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: Frank van Leynseele, Aerospace
Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington;
telephone (206) 227-2671; 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 97-NM-13-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. 97-NM-13-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA received a report indicating that an operator of a Boeing
Model 747-400 series airplane aborted takeoff because of uncommanded
automatic retraction of the leading edge flaps. When the throttles were
advanced during takeoff, the reverse thrust levers were moved upward as
they came into contact with objects placed on the central console. This
movement was sufficient to activate the mechanical interlock in the
reverse thrust levers, which resulted in an uncommanded automatic
retraction of the Group A leading edge flaps while the airplane was on
the takeoff roll. Such uncommanded automatic retraction, if not
corrected, could seriously degrade liftoff and climb capabilities, and
result in near-stall conditions at a critical phase of the flight.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-27A2356, dated December 5, 1996, which describes procedures for
replacing the cam assembly, cam bellcrank assembly, and thrust reverser
control switch actuator on all four thrust levers with new components.
Accomplishment of the replacements will preclude uncommanded automatic
retraction of the leading edge flaps during takeoff.
The alert service bulletin also describes procedures for
operational tests of the thrust reverser, automatic throttle
disconnect/reset and go-around switches, and Group A leading edge flaps
during reverse thrust operation. These tests are conducted to ensure
that the thrust reverser system operates properly.
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 require replacing the cam assembly, cam bellcrank
assembly, and thrust reverser control switch actuator on all four
thrust levers with new components. The actions would be required to be
accomplished in accordance with the alert service bulletin described
previously.
Differences Between Proposed Rule and Alert Service Bulletin
Operators should note that, although the alert service bulletin
recommends accomplishing the replacements ``as soon as manpower and
facilities are available,'' the FAA has determined that the proposed
replacements should be accomplished within 18 months after the
effective date of this AD. In developing an appropriate compliance time
for this proposed 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 replacements (8 work
hours). In light of all these factors, the FAA finds an 18-month
compliance time for initiating 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.
Cost Impact
There are approximately 394 Boeing Model 747-400 series airplanes
of the affected design in the worldwide fleet. The FAA estimates that
35 airplanes of U.S. registry would be affected by this proposed AD,
that it would take approximately 8 work hours per airplane to
accomplish the proposed actions, and that the average labor rate is $60
per work hour. Required parts would cost between $3,412 and $4,740 per
airplane. Based on these figures, the cost impact of the proposed AD is
estimated to be between $136,220 and $182,700, or between $3,892 and
$5,220 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.
[[Page 18065]]
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 97-NM-13-AD.
Applicability: Model 747-400 series airplanes, line positions
696 through 1090 inclusive; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise 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 (b) 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 uncommanded automatic retraction of the leading edge
flaps during takeoff, which would seriously degrade liftoff and
climb capabilities, and could result in near-stall conditions,
accomplish the following:
(a) Within 18 months after the effective date of this AD,
accomplish the requirements of paragraph (a)(1) or (a)(2) of this
AD, as applicable, in accordance with Boeing Alert Service Bulletin
747-27A2356, dated December 5, 1996.
(1) For Groups 1 and 2 airplanes, as listed in the alert service
bulletin: Replace the cam assembly, cam bellcrank assembly, and
thrust reverser control switch actuator on all four thrust levers
with new components.
(2) For Groups 3 and 4 airplanes, as listed in the alert service
bulletin: Replace the cam bellcrank assembly and thrust reverser
control switch actuator on all four thrust levers with new
components.
(b) 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.
(c) 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 April 7, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-9453 Filed 4-11-97; 8:45 am]
BILLING CODE 4910-13-U