[Federal Register Volume 61, Number 209 (Monday, October 28, 1996)]
[Proposed Rules]
[Pages 55584-55585]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27522]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 61, No. 209 / Monday, October 28, 1996 / 
Proposed Rules  

[[Page 55584]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-202-AD]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 31 and 35A Airplanes

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 Learjet Model 31 
and 35A airplanes, that currently requires replacement of two segments 
of 16 American Wire Gauge (AWG) wire with 8 AWG wire at the connector 
that is connected to the auxiliary cabin heater relay box. That AD was 
prompted by a report indicating that two segments of the 16 AWG wire in 
the auxiliary cabin heater, which were spliced during production, do 
not provide adequate current-carrying capacity. This new proposed 
action would require the installation of a new replacement wire 
assembly. The actions specified by the proposed AD are intended to 
prevent electrical arcing and consequent fire hazard that could result 
from wiring with inadequate current-carrying capacity.

DATES: Comments must be received by December 9, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-202-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.

FOR FURTHER INFORMATION CONTACT: Dale Bleakney, Aerospace Engineer, 
Flight Test Branch, ACE-117W, FAA, Wichita Aircraft Certification 
Office, Small Airplane Directorate, 1801 Airport Road, Room 100, Mid-
Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4135; 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 96-NM-202-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. 96-NM-202-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On May 15, 1996, the FAA issued AD 96-11-07, amendment 39-9632 (61 
FR 26090, May 24, 1996), applicable to certain Learjet Model 31 and 35A 
airplanes, to require replacement of two segments of 16 American Wire 
Gauge (AWG) wire with 8 AWG wire at the connector that is connected to 
the auxiliary cabin heater relay box. That action was prompted by a 
report that two segments of the 16 AWG wire in the auxiliary cabin 
heater that were spliced during production do not provide adequate 
current-carrying capacity. The requirements of that AD are intended to 
prevent electrical arcing and consequent fire hazard that could result 
from wiring with inadequate current-carrying capacity.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has been notified that the 
replacement installation kit specified in Learjet Service Bulletins SB 
31-21-10 and SB 35-21-24, (which were referenced in AD 96-11-07 as the 
appropriate sources of service information) contains a socket contact 
that has an incorrect part number for use in the P190 connector. This 
incorrect part number prevents the replacement equipment from being 
installed properly.
    The FAA recently reviewed and approved Revision 1 of Learjet 
Service Bulletins SB 31-21-10, dated May 17, 1996 (for Model 31 
airplanes), and SB 35-21-24, dated May 17, 1996 (for Model 35 
airplanes). These revised service bulletins describe new replacement 
procedures that include installing a new wire assembly kit that 
contains the correct socket contact, as well as a precrimped 8 AWG wire 
(2 ft. in length).
    The FAA finds that accomplishment of the wiring assembly 
installation using this new replacement installation kit will 
positively address the unsafe condition identified as electrical arcing 
and consequent fire hazard, as a result of wiring with inadequate 
current- carrying capacity.

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

[[Page 55585]]

supersede AD 96-11-07. It would require replacement of the two segments 
of 16 AWG wire with a 8 AWG wire at the P190 connector that is 
connected to the E33 auxiliary cabin heater relay box. The actions 
would be required to be accomplished in accordance with Revision 1 of 
the service bulletins described previously.
    The FAA has been advised that some operators, when attempting to 
comply with AD 96-11-07, may already have replaced the wiring assembly 
using the correct part in the P190 connector, which would be mandated 
by this proposed AD. For those operators, no additional work would be 
required by this AD.

Cost Impact

    There are approximately 52 Learjet Model 31 and 35A airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 44 
airplanes of U.S. registry would be affected by this proposed AD.
    The actions that are proposed in this AD action would take 
approximately 4 work hours per airplane to accomplish, at an average 
labor rate of $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 on U.S. operators of the proposed requirements of this 
AD is estimated to be $10,560, or $240 per airplane.
    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. The FAA has 
been advised, however, that some operators already have installed 
equipment that is the equivalent to that which would be required by 
this AD. Therefore, the future economic cost impact of this proposed 
rule on U.S. operators is expected to be less than the cost impact 
figure indicated above.

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 39-9632 (61 FR 
26090, May 24, 1996), and by adding a new airworthiness directive (AD), 
to read as follows:

Learjet, Inc.: Docket 96-NM-202-AD. Supersedes AD 96-11-07, 
Amendment 39-9632.

    Applicability: Model 31 airplanes having serial numbers 31-002 
through 31-029 inclusive, and Model 35A airplanes having serial 
numbers 35-647 through 35-670 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 electrical arcing and consequent fire hazard, 
accomplish the following:
    (a) Within 6 months after the effective date of this AD, replace 
two segments of 16 American Wire Gauge (AWG) wire with 8 AWG wire at 
the P190 connector that is connected to the E33 auxiliary cabin 
heater relay box, in accordance with Learjet Service Bulletin SB 31-
21-10, Revision 1, dated May 17, 1996 (for Model 31 airplanes), or 
Learjet Service Bulletin SB 35-21-24, Revision 1, dated May 17, 1996 
(for Model 35A airplanes), as applicable.

    Note 2: Accomplishment of the replacement in accordance with the 
procedures specified in Learjet Service Bulletin SB 31-21-10 or SB 
35-21-24 (original issue), both dated August 11, 1995, but using 
equipment that is identical or equivalent to that of the applicable 
kit specified in Revision 1 of those service bulletins, is 
considered to be acceptable for compliance with the requirements of 
paragraph (a) of this AD.

    (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 3: 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 October 21, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27522 Filed 10-25-96; 8:45 am]
BILLING CODE 4910-13-U