[Federal Register Volume 61, Number 105 (Thursday, May 30, 1996)]
[Proposed Rules]
[Pages 27030-27031]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-13498]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-240-AD]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 60 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 Learjet Model 60 
airplanes. This proposal would require modification of the aft core 
cowl nozzle of the engine nacelles. This proposal is prompted by a 
report that the sealant material in the aft core cowl nozzle of the 
engine nacelle was found to extend higher than the nozzle's forward 
flange, which can allow it to interfere with the proper operation of 
the emergency fuel shutoff actuating mechanism. The actions specified 
by the proposed AD are intended to prevent physical interference of the 
emergency fuel shutoff actuating mechanism and resultant engine 
shutdown.

DATES: Comments must be received by July 8, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-240-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 Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-
2942. This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, 
Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 
Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

FOR FURTHER INFORMATION CONTACT: Jeffrey Janusz, Aerospace Engineer, 
Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane 
Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, 
Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 
946-4148; fax (316) 946-4407.

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-240-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-240-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion -

    The FAA has received a report that, during installation of the aft 
core cowl nozzle of the engine nacelle on a Learjet Model 60 airplane, 
the sealant material in the aft core cowl nozzle was found to be 
improperly extended higher than the nozzle's forward flange. The cause 
has been attributed to the apparent improper installation of the 
sealant material during production. Sealant material in the aft core 
cowl nozzle that extends too high, if not corrected, could interfere 
with proper operation of the lever of the emergency fuel shutoff 
actuating mechanism. Such interference could result in the failure of 
the emergency fuel shutoff actuating mechanism and resultant engine 
shutdown. -
    The FAA has reviewed and approved Learjet Service Bulletin SB 60-
71-2, dated May 12, 1995, which describes procedures for modification 
of the aft core cowl nozzle of the engine nacelles. Among other 
actions, the modification involves replacing the sealant on the aft 
core cowl nozzle with a filler made from 6061 aluminum, and 
reidentifying the aft core cowl nozzle. The modification will ensure 
that the sealant does not interfere with the function of the emergency 
fuel shutoff actuating mechanism. -
    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 modification of the aft core cowl nozzle of 
the engine nacelles. The actions would be required to be accomplished 
in accordance with the service bulletin described previously. -
    There are approximately 39 Learjet Model 60 airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 26 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 44 work hours per airplane to accomplish 
the proposed actions, and that the average labor rate is $60 per work 
hour. Required parts would be supplied by the manufacturer at no cost 
to the operators. Based on these figures, the cost impact of the 
proposed AD on U.S. operators is estimated to be $68,640, or $2,640 per 
airplane. -
    The 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

[[Page 27031]]

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:

Learjet: Docket 95-NM-240-AD.

     -Applicability: Model 60 airplanes, as listed in Learjet 
Service Bulletin SB 60-71-2, dated May 12, 1995; 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 the sealant material in the aft core cowl nozzle of 
the engine nacelles from interfering with the lever of the emergency 
fuel shutoff actuating mechanism, which could result in the failure 
of the emergency fuel shutoff actuating mechanism and resultant 
engine shutdown, accomplish the following: -
    (a) Within 90 days after the effective date of this AD, modify 
the aft core cowl nozzle of the engine nacelles in accordance with 
Learjet Service Bulletin SB 60-71-2, dated May 12, 1995. -
    (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, Wichita Aircraft Certification 
Office (ACO), FAA, Small 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, Wichita ACO.

     -Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita 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 May 22, 1996.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-13498 Filed 5-29-96; 8:45 am]
BILLING CODE 4910-13-U