[Federal Register Volume 64, Number 160 (Thursday, August 19, 1999)]
[Proposed Rules]
[Pages 45211-45213]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21575]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-351-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 737-300, -400 and 
-500 series airplanes. This proposal would require replacement, with 
new parts, of the existing actuators or the rod ends on the existing 
actuators at wing leading edge slat positions 1, 2, 5, and 6. This 
proposal is prompted by reports indicating that the rod ends on several 
leading edge slat actuators have fractured. The actions specified by 
the proposed AD are intended to prevent fatigue cracking of the rod 
ends of the leading edge slat actuators, which could result in 
uncommanded deployment of the wing leading edge slat and consequent 
reduced controllability of the airplane.

DATES: Comments must be received by October 4, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-351-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00

[[Page 45212]]

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: Robert C. Jones, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056; telephone (425) 227-1118; 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-351-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-351-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of fractured rod ends on several 
actuators for the wing leading edge slats on Boeing Model 737-300, -
400, and -500 series airplanes. One reported case of an actuator rod 
end fracture resulted in an air turnback after the airplane experienced 
uncommanded roll during flight. It has been determined that these 
fractures are the result of fatigue cracking. Failure of the actuator 
rod end, under certain flight conditions, could result in an 
uncommanded deployment of the affected wing leading edge slat and 
consequent reduced controllability of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
737-27A1211, dated November 19, 1998, which describes procedures for 
replacement of the existing wing leading edge slat actuator with a new 
actuator, or replacement of the rod end on the existing leading edge 
slat actuator. Accomplishment of either of these actions specified in 
the alert service bulletin 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 require accomplishment of the actions specified in 
the alert service bulletin described previously.

Cost Impact

    There are approximately 1,897 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 720 airplanes of U.S. 
registry would be affected by this proposed AD.
    Replacement of the leading edge slat actuator with an actuator that 
has a new rod end is proposed as one option for compliance with this AD 
action. Replacement of the actuators on slat positions 1, 2, 5, and 6 
would take approximately 3 hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Required parts cost 
approximately $32,252 per airplane. Based on these figures, the cost 
impact of the installation of actuators with new rod ends as proposed 
as an option by this AD on U.S. operators is estimated to be $32,432 
per airplane.
    In lieu of installation of an actuator with a new rod end, this 
proposed AD provides an option for replacement of the rod ends on the 
existing actuators. This action would take approximately 4 work hours 
per airplane, at an average labor rate of $60 per work hour. Required 
parts would cost between approximately $5,928 and $21,544 per airplane. 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be between $6,168 and $21,784 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. 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 98-NM-351-AD.


[[Page 45213]]


    Applicability: Model 737-300, -400, and -500 series airplanes; 
line numbers 1001 through 3063 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 
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 (c) 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 fatigue cracking of the rod ends on the 
leading edge slat actuators, which could result in uncommanded 
deployment of the wing leading edge slat and consequent reduced 
controllability of the airplane, accomplish the following:
    (a) Within 24 months after the effective date of this AD: 
Replace the leading edge slat actuator with an actuator that has a 
new rod end, or replace the rod end on the existing slat actuator 
with a new rod end, at slat positions 1, 2, 5, and 6; in accordance 
with the Accomplishment Instructions in Boeing Alert Service 
Bulletin 737-27A1211, dated November 19, 1998.

Spares

    (b) As of the effective date of this AD, no person shall install 
any part having a part number identified in the ``Existing Part 
Number'' column of Section 2.E. of Boeing Alert Service Bulletin 
737-27A1211, dated November 19, 1998, on any airplane.

Alternative Methods of Compliance

    (c) 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.

Special Flight Permits

    (d) 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 August 13, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-21575 Filed 8-18-99; 8:45 am]
BILLING CODE 4910-13-U