[Federal Register Volume 59, Number 186 (Tuesday, September 27, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-23718]


[[Page Unknown]]

[Federal Register: September 27, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-191-AD; Amendment 39-8748; AD 93-23-12]

 

Airworthiness Directives; Learjet Model 60 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; correction.

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SUMMARY: This document corrects information in an existing 
airworthiness directive (AD), applicable to certain Learjet Model 60 
airplanes, that currently requires deactivation of the auxiliary cabin 
and cockpit heating systems and installation of placards. This action 
corrects the applicability of the rule. This action is necessary to 
ensure that only airplanes subject to the addressed unsafe condition 
are subject to the requirements of the rule.

DATES: Effective December 15, 1993.
    The incorporation by reference of certain publications listed in 
the regulations was previously approved by the Director of the Federal 
Register as of December 15, 1993 (58 FR 63060, November 30, 1993).

ADDRESSES: The service information referenced in this AD may be 
obtained from Learjet, Inc., P.O. Box 7707, Wichita, Kansas 67277-7707. 
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, 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: C. Dale Bleakney, Aerospace Engineer, 
Systems and Equipment Branch, ACE-130W, FAA, Small Airplane 
Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, 
Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 
946-4135; fax (316) 946-4407.

SUPPLEMENTARY INFORMATION: On November 22, 1993, the FAA issued AD 93-
23-12, amendment 39-8748 (58 FR 63060, November 30, 1993), to require 
deactivation of the auxiliary cabin and cockpit heating systems on all 
Learjet Model 60 airplanes, and the installation of a placard stating, 
``Cabin and Cockpit Heat Inop.'' That action was prompted by a report 
of a fire in the aft fuselage of one airplane, which had resulted from 
miswiring that was installed in an auxiliary cabin heater during 
manufacture. The actions required by that AD are intended to prevent 
overheating of the auxiliary cabin and cockpit heaters, which 
potentially could result in a fire.
    Recently, the FAA has become aware of the fact that the 
applicability of the AD is unnecessarily broad. In developing the AD, 
the FAA intended that its applicability be coextensive with the 
effectivity listing of Learjet Alert Service Bulletin SB A60-21-1, 
dated November 1, 1993. (That service bulletin was referenced in the 
rule as the appropriate source of service information.) That service 
bulletin indicates that only airplanes having serial numbers 60-002 
through 60-021, inclusive, are subject to the addressed unsafe 
condition; all other airplanes of this model were modified during 
production in such a way so as to preclude the unsafe condition. 
However, the applicability of the AD, as published, inadvertently 
indicated that all airplanes of this model were applicable to the 
requirements of the AD, rather than just those having serial numbers 
60-002 through 60-021. That inadvertent action incorrectly made the 
requirements of the AD redundant for airplanes other than those with 
the specified serial numbers.
    The FAA has determined that it is appropriate to take action to 
correct the applicability of AD 93-23-12 to specify only airplanes that 
are subject to the addressed unsafe condition. Therefore, action must 
be taken to correctly limit the AD's applicability to only Learjet 
Model 60 airplanes having serial numbers 60-002 through 60-021, 
inclusive.
    Action is taken herein to correct the error and to correctly add 
the AD as an amendment to section 39.13 of the Federal Aviation 
Regulations (14 CFR 39.13). The effective date of the rule remains 
December 15, 1993.
    The final rule is being reprinted in its entirety for the 
convenience of affected operators.
    Since this action only corrects an inadvertent error in the 
applicability of the rule, so as to eliminate airplanes not subject to 
the identified unsafe condition, it has no adverse economic impact and 
imposes no additional burden on any person. Therefore, notice and 
public procedures hereon are unnecessary.

List of Subjects in 14 CFR Part 39

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

Adoption of the Correction

    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by correctly adding the following 
airworthiness directive (AD):

93-23-12 Learjet, Inc.: Amendment 39-8748. Docket 93-NM-191-AD.

    Applicability: Model 60 airplanes having serial numbers 60-002 
through 60-021, inclusive, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent overheating of the auxiliary cabin and cockpit 
heaters, which could potentially result in a fire, accomplish the 
following:
    (a) Within 10 flight hours after the effective date of this AD, 
deactivate the auxiliary cabin and cockpit heating systems; and 
install a placard stating, ``Cabin and Cockpit Heat Inop'' adjacent 
to the AUX HT Switch (S44) on the co-pilot's switch panel; in 
accordance with Learjet Alert Service Bulletin SB A60-21-1, dated 
November 1, 1993.
    (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: 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 
section 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 deactivation and placard installation shall be done in 
accordance with Learjet Alert Service Bulletin SB A60-21-1, dated 
November 1, 1993. This incorporation by reference was approved by 
the Director of the Federal Register, in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51, as of December 15, 1993 (58 FR 63060, 
November 30, 1993). Copies may be obtained from Learjet, Inc., P.O. 
Box 7707, Wichita, Kansas 67277-7707. Copies may be inspected at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Wichita ACO, 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 December 15, 1993.

    Issued in Renton, Washington, on September 20, 1994.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-23718 Filed 9-26-94; 8:45 am]
BILLING CODE 4910-13-U