Airworthiness Directives; Learjet Model 23, 24, 25, 28, 29, 31, 35, 36, and 55 Series Airplanes

[Federal Register Volume 66, Number 73 (Monday, April 16, 2001)]
[Rules and Regulations]
[Pages 19387-19389]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9018]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-76-AD; Amendment 39-12177; AD 2001-07-11]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 23, 24, 25, 28, 29, 31, 
35, 36, and 55 Series 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 all Learjet Model 23, 24, 25, 28, 29, 31, 35, 36, and 
55 series airplanes. This action requires an inspection to determine if 
tires on the main landing gear have a certain part number and certain 
serial numbers, and replacement with a tire having a part number that 
does not contain those certain serial numbers, if necessary. This 
action is necessary to prevent separation of the tread of main landing 
gear tires, which could cause damage to the structure and major systems 
of the airplane, and consequent reduced controllability of the airplane 
on the ground during takeoff and landing. This action is intended to 
address the identified unsafe condition.

DATES: Effective May 1, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 1, 2001.
    Comments for inclusion in the Rules Docket must be received on or 
before June 15, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-76-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-76-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    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 FAA, Transport Airplane Directorate, 
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: Robert Busto, Aerospace Engineer, 
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, Kansas 67209; telephone (316) 946-4157; fax (316) 
946-4407.

SUPPLEMENTARY INFORMATION: The FAA has received reports that certain 
main landing gear tires have lost the entire tread during takeoff or 
landing of Learjet Model 23, 24, 25, 28, 29, 31, 35, 36, and 55 series 
airplanes. Investigation by the tire manufacturer indicates that during 
manufacturing, a block of tires were processed that contained certain 
faults. The tire manufacturer has determined that tires having part 
number (P/N) 178K23-5 within the serial number range of 0148xxxx 
through 0152xxxx were affected. Separation of tire tread from the main 
landing gear tires could cause damage to the structure and major 
systems of the airplane, and consequent reduced controllability of the 
airplane on the ground during takeoff and landing.

Explanation of Relevant Service Information

    Bombardier (Learjet) has issued Advisory Wire (AW), 32-021, dated 
February 5, 2001, which describes procedures for inspecting Goodyear 
Flight Eagle main landing gear tires to determine if a certain part 
number and certain serial numbers are installed. The AW also describes 
procedures to replace any of the specified tires with new or 
serviceable tires having a part number containing a serial number other 
than those specified in the AW. Accomplishment of the actions specified 
in the AW is intended to adequately address the identified unsafe 
condition.
    The AW also references Goodyear Service Bulletin GY SB 2001-32-001, 
dated February 2, 2001, as an additional source of service information 
for accomplishment of the inspection, and

[[Page 19388]]

replacement of main landing gear tires, if necessary.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to prevent damage to major systems of the airplane, and 
consequent reduced controllability of the airplane on the ground during 
takeoff and landing. This AD requires accomplishment of the actions 
specified in the AW described previously, except as discussed below.

Differences Between the Service Information and This AD

    Operator's should note that, although the AW specifies that the 
inspection of the main landing gear tires, and replacement if 
necessary, should be accomplished ``prior to next flight,'' this AD 
requires that those actions be accomplished within 5 days after the 
effective date of this AD. We find that a 5-day compliance time will 
provide the operator with a reasonable time to perform the inspection, 
but will not adversely affect the safety of the fleet.

Determination of Rule's Effective Date

    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.
    Submit comments using the following format:
    <bullet> Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    <bullet> For each issue, state what specific change to the AD is 
being requested.
    <bullet> Include justification (e.g., reasons or data) for each 
request.
    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 2001-NM-76-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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), 40113, 44701.


Sec. 39.13  [Amended]

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

2001-07-11  Learjet Inc.: Amendment 39-12177. Docket 2001-NM-76-AD.
    Applicability: All Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-
A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F, 28, 29, 31, 31A, 
35, 35A (C-21A military), 36, 36A, 55, 55B, and 55C airplanes; 
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 (c) 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 separation of the tread of main landing gear tires, 
which could cause damage to the structure and major systems of the 
airplane, and consequent reduced controllability of the airplane on 
the ground during takeoff and landing; accomplish the following:

Inspection, and Replacement if Necessary

    (a) Within 5 days after the effective date of this AD: Perform a 
general visual inspection of the main landing gear tires to 
determine if any tire has Goodyear part number (P/N) 178K23-5 within 
the serial number range of 0148xxxx through 0152xxxx inclusive, per 
Bombardier (Learjet) Advisory Wire 32-021, dated February 5, 2001.

    Note 2: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or drop-light, and may require removal or opening of 
access panels or doors. Stands, ladders, or

[[Page 19389]]

platforms may be required to gain proximity to the area being 
checked.''


    Note 3: Bombardier (Learjet) AW 32-021 references Goodyear 
Service Bulletin GY SB 2001-32-001, dated February 2, 2001, as an 
additional source of service information.

    (1) If no tires have P/N 178K23-5, no further actions is 
required by this paragraph.
    (2) If any tire has P/N 178K23-5 but does not contain any serial 
number 0148xxxx through 0152 inclusive, no further action is 
required by this paragraph.
    (3) If any tire has P/N 178K23-5 and does contain any serial 
number 0148xxxx through 0152xxxx inclusive: Before further flight, 
replace the tire with a new or serviceable tire that does not have 
P/N 178K23-5 with a serial number 0148xxxx through 0152xxxx 
inclusive.
    (b) As of the effective date of this AD, no person shall install 
a main landing gear tire having P/N 178K23-5 that contains any 
serial number 0148xxxx through 0152xxxx inclusive, on any airplane.

Alternative Methods of Compliance

    (c) 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). 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita ACO.

Special Flight Permits

    (d) 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.

Incorporation by Reference

    (e) The inspection, and replacement if necessary, shall be done 
in accordance with Bombardier (Learjet) Advisory Wire 32-021, dated 
February 5, 2001. 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 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, Wichita Aircraft Certification 
Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, 
Kansas 67209; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (f) This amendment becomes effective on May 1, 2001.

    Issued in Renton, Washington, on April 5, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-9018 Filed 4-13-01; 8:45 am]
BILLING CODE 4910-13-U

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