[Federal Register Volume 70, Number 65 (Wednesday, April 6, 2005)]
[Proposed Rules]
[Pages 17349-17351]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-6767]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20872; Directorate Identifier 2004-NM-271-AD]
RIN 2120-AA64


Airworthiness Directives; Learjet 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), and 36 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Learjet 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), and 36 airplanes. This proposed AD would require a one-time 
inspection of the center ball of the aileron control cable or cables 
for a defective swage, and corrective actions if necessary. This 
proposed AD is prompted by a report indicating that an aileron cable 
failed on one affected airplane when the cable underwent a tension 
check. We are proposing this AD to prevent severe weakening of the 
aileron cable, and consequent reduced controllability of the airplane.

DATES: We must receive comments on this proposed AD by May 23, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     By fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. 
and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942.
    You can examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or in person at the Docket Management Facility, 
U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, 
on the plaza level of the Nassif Building, Washington, DC. This docket 
number is FAA-2005-20872; the directorate identifier for this docket is 
2004-NM-271-AD.

FOR FURTHER INFORMATION CONTACT: David Hirt, 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) 946-4156; fax (316) 
946-4107.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-20872; 
Directorate Identifier 2004-NM-271-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that website, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit http://dms.dot.gov.

Examining the Docket

    You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the DMS receives them.

Discussion

    We have received a report indicating that an aileron cable failed 
on a Learjet Model 35A (C-21A) airplane when the cable underwent a 
tension check while being installed. Further investigation showed that 
an over-sized ball was swaged onto the cable during manufacture. 
Swaging an over-sized ball onto a cable allows excess material into the 
swaging die, which causes the ball to over-swage and then sever the 
cable strands. This condition, if not corrected, could result in severe 
weakening of the aileron cable, and consequent reduced controllability 
of the airplane.
    The subject area on Learjet 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, and 36 airplanes is identical to those on the affected Model 
35A (C-21A) airplane. Therefore, all these airplanes may be subject to 
the same unsafe condition.

Relevant Service Information

    We have reviewed the Learjet service bulletins in the following 
table.

                        Learjet Service Bulletins
------------------------------------------------------------------------
    Alert service bulletin             Date                Model
------------------------------------------------------------------------
A23/24/25-27-17...............  December 23, 2002  23, 24, 24A, 24B, 24B-
                                                    A, 24C, 24D, 24D-A,
                                                    24E, 24F, 24F-A, 25,
                                                    25A, 25B, 25C, 25D,
                                                    and 25F.
A28/29-27-24..................  December 23, 2002  28 and 29.

[[Page 17350]]

 
A31-27-25.....................  December 23, 2002  31 and 31A.
A35/36-27-42..................  December 23, 2002  35, 35A (C-21A), and
                                                    36.
------------------------------------------------------------------------

    These service bulletins describe procedures for visually inspecting 
the center ball of the aileron control cable or cables for a defective 
swage, which includes an extruded shoulder and/or face deformation. If 
the inspection shows a defective swage, the service bulletins describe 
procedures for, among other actions, replacing the aileron cable with a 
new cable. The service bulletins also request that operators send to 
the manufacturer all defective parts, and a report indicating 
compliance with the applicable service bulletin. Accomplishing the 
actions specified in the service information is intended to adequately 
address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. Therefore, we are proposing this AD, which 
would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Differences Between the Proposed AD and the Service Bulletins.''

Differences Between the Proposed AD and the Service Bulletins

    Operators should note that, although the Accomplishment 
Instructions of the referenced service bulletin describe procedures for 
submitting a report showing compliance with the service bulletin and 
for returning any discrepant parts to the manufacturer, this proposed 
AD would not require those actions.
    The service bulletins recommend that operators accomplish the 
actions ``as soon as possible'' within 10 flight hours after receiving 
the applicable service bulletin. This proposed AD would require that 
operators accomplish the actions within 100 flight hours, or 90 days 
after the effective date of the proposed AD, whichever occurs first. We 
find that the proposed compliance time addresses the unsafe condition 
soon enough to maintain an adequate level of safety for the affected 
fleet. In developing an appropriate compliance time for this AD we 
considered the degree of urgency associated with addressing the unsafe 
condition, and the maximum interval of time allowable for all affected 
airplanes to continue to operate without compromising safety.

Clarification of Inspection Language

    The service bulletins describe procedures for ``visually 
inspecting'' the center ball of the aileron control cable or cables. In 
this proposed AD we refer to this inspection as a ``detailed 
inspection.'' Note 1 of this proposed AD defines this inspection.

Costs of Compliance

    There are about 1,704 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 1,136 airplanes of 
U.S. registry. The proposed inspection would take about 1 work hour per 
airplane, at an average labor rate of $65 per work hour. Based on these 
figures, the estimated cost of the proposed AD for U.S. operators is 
$73,840, or $65 per airplane.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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.
    For the reasons discussed above, I certify that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

Learjet: Docket No. FAA-2005-20872; Directorate Identifier 2004-NM-
271-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by May 23, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Learjet 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), and 36 airplanes; certificated in any 
category; as identified in the Learjet alert service bulletins in 
Table 1 of this AD.

[[Page 17351]]



                   Table 1.--Learjet Service Bulletins
------------------------------------------------------------------------
    Alert service bulletin             Date                Model
------------------------------------------------------------------------
A23/24/25-27-17...............  December 23, 2002  23, 24, 24A, 24B, 24B-
                                                    A, 24C, 24D, 24D-A,
                                                    24E, 24F, 24F-A, 25,
                                                    25A, 25B, 25C, 25D,
                                                    and 25F.
A28/29-27-24..................  December 23, 2002  28 and 29.
A31-27-25.....................  December 23, 2002  31 and 31A.
A35/36-27-42..................  December 23, 2002  35, 35A (C-21A), and
                                                    36.
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD was prompted by a report indicating that an aileron 
cable failed on one affected airplane when the cable underwent a 
tension check. We are issuing this AD to prevent severe weakening of 
the aileron cable, and consequent reduced controllability of the 
airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Inspection and Corrective Action

    (f) Within 100 flight hours, or 90 days after the effective date 
of this AD, whichever occurs first: Do a detailed inspection of the 
center ball of the aileron control cable or cables for a defective 
swage, and before further flight replace any damaged or defective 
cable with a new cable. Unless otherwise specified in this AD, do 
all actions in accordance with the Accomplishment Instructions of 
the applicable service bulletin in Table 1 of this AD.

    Note 1: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Parts Installation

    (g) As of the effective date of this AD, no person may install 
on any airplane an aileron control cable unless it has been 
inspected in accordance with paragraph (f) of this AD.

No Reporting or Parts Return Requirement

    (h) Although the service bulletins in Table 1 of this AD have 
procedures for submitting a report showing compliance with the 
applicable service bulletin and for returning any discrepant parts 
to the manufacturer, this AD does not include those requirements.

Alternative Methods of Compliance (AMOCs)

    (i) The Manager, Wichita Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

    Issued in Renton, Washington, on March 25, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-6767 Filed 4-5-05; 8:45 am]
BILLING CODE 4910-13-P