[Federal Register Volume 60, Number 196 (Wednesday, October 11, 1995)]
[Rules and Regulations]
[Pages 52843-52844]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-24902]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-178-AD; Amendment 39-9388; AD 95-21-03]


Airworthiness Directives; Learjet Model 31A and 60 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Learjet Model 31A and 60 airplanes. This 
action requires an inspection to identify the serial numbers of the 
engine fire pull switch assemblies, and replacement of the assembly 
with a serviceable assembly, if necessary. This amendment is prompted 
by a report indicating that certain engine fire pull switch assemblies 
may contain microswitches that were manufactured with internal defects. 
Such defects could result in electrical failure of the switch in the 
open or closed position. The actions specified in this AD are intended 
to prevent failure of the switch, which could result in the inability 
of the flight crew to shut down certain systems or to arm the fire 
extinguishers due to inoperation of the fire tee handle, or inadvertent 
shutdown of one or both engines due to fuel starvation.

DATES: Effective October 26, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 26, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before December 11, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-178-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. The service information referenced in 
this AD may be obtained from Gates Learjet, Mid-Continent Airport, P. 
O. Box 7707, Wichita, Kansas 67277. This information may be examined at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Wichita Aircraft Certification Office, Small 
Airplane Directorate, 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, 
FAA, Wichita Aircraft Certification Office, Small Airplane Directorate, 
1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; 
telephone (316) 946-4135; fax (316) 946-4407.

SUPPLEMENTARY INFORMATION: The FAA has received a report indicating 
that a certain batch of engine fire pull switch assemblies may contain 
microswitches that were manufactured with internal defects. These 
assemblies are installed on Learjet Model 31A and 60 airplanes. The 
left-hand (pilot) and right-hand (copilot) engine fire pull switch 
assemblies contain four microswitches each, all of which may be 
affected. Such internal defects can cause electrical failure of the 
switch in the open or closed position, regardless of the position of 
the ENG FIRE PULL tee handle. If the switch fails in the open position, 
the fire tee handle would be inoperable. This condition, if not 
corrected, could result in the inability of the flight crew to shut 
down certain systems (such as the fuel or hydraulics system) or to arm 
the fire extinguishers. Failure of the switch in the closed position 
could result in fuel starvation. This condition, if not corrected, 
could result in inadvertent shutdown of one or both engines during 
flight.
    The FAA has reviewed and approved Learjet Alert Service Bulletin SB 
A31-26-3 (for Model 31A airplanes) and SB A60-26-1 (for Model 60 
airplanes), both dated July 14, 1995, which describe procedures for an 
inspection to identify the serial numbers of the left-hand (pilot) and 
right-hand (copilot) engine fire pull switch assemblies, and 
replacement of any suspect assembly with a serviceable assembly. 
Replacement of suspect assemblies will restore the integrity of the 
engine fire pull switch.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Learjet Model 31A and 60 airplanes of the 
same type design, this AD is being issued to prevent electrical failure 
of the microswitches in the engine fire pull switch assembly, which 
could result in the inability of the flight crew to shut down certain 
systems or to arm the fire extinguishers, or inadvertent shutdown of 
one or both engines. This AD requires an inspection to identify the 
serial numbers of the left-hand (pilot) and right-hand (copilot) engine 
fire pull switch assemblies, and replacement of any suspect assembly 
with a serviceable assembly. The actions are required to be 
accomplished in accordance with the alert service bulletins described 
previously.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-NM-178-AD.'' The postcard will be date stamped and 
returned to the commenter. 

[[Page 52844]]

    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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), 40101, 40113, 44701.


Sec. 39.13   [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

95-21-03  Learjet: Amendment 39-9388. Docket 95-NM-178-AD.

    Applicability: Model 31A airplanes, serial numbers 31-093 
through 31-108 inclusive; and Model 60 airplanes, serial numbers 60-
034 through 60-061 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 use the authority 
provided in paragraph (d) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent electrical failure of the microswitches in the engine 
fire pull switch assembly, which could result in the inability of 
the flight crew to shut down certain systems or to arm the fire 
extinguishers, or inadvertent shutdown of one or both engines, 
accomplish the following:
    (a) For Model 31A airplanes: Within 50 hours time-in-service 
after the effective date of this AD, perform an inspection to 
identify the serial numbers of the left-hand (pilot) and right-hand 
(copilot) engine fire pull switch assemblies in accordance with 
Learjet Alert Service Bulletin SB A31-26-3, dated July 14, 1995.
    (1) If the serial number of the assembly is not identified as 
2326, 2363 through 2377 inclusive, or 3000 through 3019 inclusive: 
No further action is required by this AD.
    (2) If the serial number of the assembly is identified as 2326, 
2363 through 2377 inclusive, or 3000 through 3019 inclusive: Prior 
to further flight, replace the engine fire pull switch assembly with 
a serviceable assembly in accordance with the alert service 
bulletin.
    (b) For Model 60 airplanes: Within 50 hours time-in-service 
after the effective date of this AD, perform an inspection to 
identify the serial numbers of the left-hand (pilot) and right-hand 
(copilot) engine fire pull switch assemblies in accordance with 
Learjet Alert Service Bulletin SB A60-26-1, dated July 14, 1995.
    (1) If the serial number of the assembly is not identified as 
106 through 168 inclusive: No further action is required by this AD.
    (2) If the serial number of the assembly is identified as 106 
through 168 inclusive: Prior to further flight, replace the engine 
fire pull switch assembly with a serviceable assembly in accordance 
with the alert service bulletin.
    (c) As of the effective date of this AD, no person shall install 
on any airplane an engine fire pull switch assembly having a serial 
number identified in paragraph (c)(1) or (c)(2) of this AD, as 
applicable, unless such serial number is preceded by the letters 
``RS'' and accompanied by a repair date code later than June 1, 
1995.
    (1) For Model 31A airplanes: Serial numbers 2326, 2363 through 
2377 inclusive, and 3000 through 3019 inclusive.
    (2) For Model 60 airplanes: Serial numbers 106 through 168 
inclusive.
    (d) 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.

    (e) 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.
    (f) The inspection and replacement shall be done in accordance 
with Learjet Alert Service Bulletin SB A31-26-3, dated July 14, 
1995, and Learjet Alert Service Bulletin SB A60-26-1, dated July 14, 
1995. 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. Copies may be obtained from Gates Learjet, Mid-Continent 
Airport, PO Box 7707, Wichita, Kansas 67277. Copies may be inspected 
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., 
Renton, Washington; or at the FAA, Wichita Aircraft Certification 
Office, Small Airplane Directorate, 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.
    (g) This amendment becomes effective on October 26, 1995.

    Issued in Renton, Washington, on October 2, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-24902 Filed 10-10-95; 8:45 am]
BILLING CODE 4910-13-U