[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