Airworthiness Directives; Learjet Model 31 and 35A Airplanes

[Federal Register Volume 63, Number 54 (Friday, March 20, 1998)]
[Rules and Regulations]
[Pages 13498-13500]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-6950]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-202-AD; Amendment 39-10406; AD 98-06-28]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 31 and 35A Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes 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 amendment requires the installation of 
a new replacement wire assembly. The actions specified by this AD are 
intended to prevent electrical arcing and consequent fire hazard that 
could result from wiring with inadequate current-carrying capacity.

DATES: Effective April 24, 1998.
    The incorporation by reference of Learjet Service Bulletin SB 31-
21-10, Revision 1, dated May 17, 1996, and Learjet Service Bulletin SB 
35-21-24, Revision 1, dated May 17, 1996, as listed in the regulations, 
is approved by the Director of the Federal Register as of April 24, 
1998.
    The incorporation by reference of Learjet Service Bulletin SB 31-
21-10, dated August 11, 1995, and Learjet Service Bulletin SB 35-21-24, 
dated August 11, 1995, as listed in the regulations, was approved 
previously by the Director of the Federal Register as of June 28, 1996 
(61 FR 26090, May 24, 1996).

ADDRESSES: The service information referenced in this AD may be 
obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-
2942. This information may be examined at the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, Rules Docket, 
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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 96-11-07, 
amendment 39-9632 (61 FR 26090, May 24, 1996), which is applicable to 
certain Learjet Model 31 and 35A airplanes, was published in the 
Federal Register on October 28, 1996 (61 FR 55584). The action proposed 
to require the

[[Page 13499]]

installation of a new replacement wire assembly.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were submitted in response 
to the proposal or the FAA's determination of the cost to the public.

Conclusion

    The FAA has determined that air safety and the public interest 
require the adoption of the rule as proposed.

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 will be affected by this AD.
    The actions that are currently required by AD 96-11-07, and 
retained in this AD, take approximately 4 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts will be supplied by the manufacturer at no cost to the operators. 
Based on these figures, the cost impact of the required actions on U.S. 
operators is estimated to be $10,560, or $240 per airplane.
    The cost impact figure discussed above is 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 adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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), 
amendment 39-10406, to read as follows:

98-06-28  Learjet, Inc.: Amendment 39-10406. 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 
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.
    (d) The actions shall be done in accordance with Learjet Service 
Bulletin SB 31-21-10, dated August 11, 1995, or Revision 1, dated 
May 17, 1996, or Learjet Service Bulletin SB 35-21-24, dated August 
11, 1995, or Revision 1, dated May 17, 1996; as applicable.
    (1) The incorporation by reference of Learjet Service Bulletin 
SB 31-21-10, Revision 1, dated May 17, 1996, and Learjet Service 
Bulletin SB 35-21-24, Revision 1, dated May 17, 1996, is approved by 
the Director of the Federal Register in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51.
    (2) The incorporation by reference of Learjet Service Bulletins 
SB 31-21-10 dated August 11, 1995 and Learjet SB 35-21-24 dated 
August 11, 1995, was approved previously by the Director of the 
Federal Register as of June 28, 1996 (61 FR 26090, May 24, 1996).
    (3) Copies may be obtained from Learjet, Inc., One Learjet Way, 
Wichita, Kansas 67209-2942. Copies may be inspected 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; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on April 24, 1998.


[[Page 13500]]


    Issued in Renton, Washington, on March 11, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-6950 Filed 3-19-98; 8:45 am]
BILLING CODE 4910-13-U

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