[Federal Register Volume 68, Number 156 (Wednesday, August 13, 2003)]
[Rules and Regulations]
[Pages 48274-48275]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-20699]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-142-AD; Amendment 39-13272; AD 2003-16-19]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 45 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 45 airplanes. This action requires 
replacement of the horizontal stabilizer actuator assembly (HSAA) with 
a new HSAA. This action is necessary to prevent structural failure of 
the HSAA, which could result in possible loss of control of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Effective August 13, 2003.
    Comments for inclusion in the Rules Docket must be received on or 
before October 14, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2003-NM-142-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. 2003-NM-142-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 or 2000 or 
ASCII text.
    Information pertaining to this amendment may be examined at the 
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.

FOR FURTHER INFORMATION CONTACT: Greg Davied, Aerospace Engineer, 
Airframe and Propulsion Branch, ACE-118W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, Kansas 67209; telephone (316) 946-4128; fax (316) 
946-4107.

SUPPLEMENTARY INFORMATION:

Background

    On April 11, 2003, the FAA issued AD 2003-06-51, amendment 39-13121 
(68 FR 19328, April 21, 2003), applicable to certain Learjet Model 45 
airplanes, to require an inspection to determine the part number (P/N) 
of the horizontal stabilizer actuator assembly (A66) (HSAA), and 
replacement of any suspect HSAA (A66) having P/N 6627401000-001 or 
SA9200F with a new or serviceable HSAA (A66) having P/N 6627401000-005. 
That action was prompted by a report of severe vibration followed by a 
rapid nose down pitch change on a Learjet Model 45 airplane. The cause 
of the incident is attributed to brittle fracture material properties 
of certain components of the HSAA. The requirements of that AD are 
intended to prevent structural failure of the HSAA, which could result 
in possible loss of control of the airplane.

FAA's Determination Since Issuance of AD 2003-06-51

    Since issuance of AD 2003-06-51, we have determined that the MPC 
Products Corporation acme screw having P/N 2A94568008 and nut having P/
N 2A94567005 within the new HSAA having P/N 6627401000-005 installed 
per that AD are physically similar (not identical) to and have the same 
material as the suspect assembly having P/N 6627401000-001. Although 
the HSAA having P/N-005 is an improvement over the P/N-001, it was not 
manufactured per the type design data. A brittle fracture could occur 
on the acme screw and nut within the assembly having P/N-005, similar 
to that on the assembly having P/N-001. During our investigation of 
this problem, we determined that the configuration and quality controls 
over the production of these parts were so deficient that we do not 
have confidence that the airplane can be operated safely for any period 
of time. Therefore, this AD allows operation only for the purpose of 
positioning the airplane where the replacement required by this AD can 
be accomplished. The airplane manufacturer is currently substantiating 
the design data for the new replacement part. We anticipate that the 
new part will be available in the near future.

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

[[Page 48275]]

type design registered in the United States, this AD requires 
replacement of the HSAA with a new HSAA. The effect of this AD is that 
operation is prohibited after the effective date of this AD, except to 
position the airplane as described previously, until the required 
replacement can be accomplished.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Changes to 14 CFR Part 39/Effect on the AD

    On July 10, 2002, we issued a new version of 14 CFR part 39 (67 FR 
47997, July 22, 2002), which governs our AD system. The regulation now 
includes material that relates to altered products, special flight 
permits, and alternative methods of compliance (AMOCs). Because we have 
now included this material in part 39, only the office authorized to 
approve AMOCs is identified in each individual AD.

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:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the AD is 
being requested.
    [sbull] 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 2003-NM-142-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, Safety.

Adoption of the Amendment

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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

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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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2003-16-19 Learjet: Amendment 39-13272. Docket 2003-NM-142-AD.

    Applicability: All Model 45 airplanes, certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent structural failure of the horizontal stabilizer 
actuator assembly (HSAA), which could result in possible loss of 
control of the airplane, accomplish the following:

Replacement

    (a) Except as provided by paragraph (b) of this AD, before 
further flight after the effective date of this AD, replace the HSAA 
having part number (P/N) 6627401000-005 with a new HSAA, per a 
method approved by the Manager, Wichita Aircraft Certification 
Office (ACO), FAA.

Flight Limits

    (b) Non-revenue flights are permitted within 3 days after the 
effective date of this AD only for the purpose of positioning the 
airplane to a location where the replacement required by paragraph 
(a) of this AD can be accomplished.

Parts Installation

    (c) As of the effective date of this AD, no person may install 
an HSAA, P/N 6627401000-005, on any airplane.

Alternative Methods of Compliance

    (d) In accordance with 14 CFR 39.19, the Manager, Wichita 
Aircraft Certification Office (ACO), FAA, is authorized to approve 
alternative methods of compliance for this AD.

Effective Date

    (e) This amendment becomes effective August 13, 2003.

    Issued in Renton, Washington, on August 8, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-20699 Filed 8-12-03; 8:45 am]
BILLING CODE 4910-13-P