[Federal Register Volume 71, Number 158 (Wednesday, August 16, 2006)]
[Proposed Rules]
[Pages 47154-47156]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-13453]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-25563; Directorate Identifier 2006-NM-083-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), 36, 36A, 55, 55B, and 55C 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), 36, 36A, 55, 55B, and 55C airplanes. This proposed AD would 
require modifying the left- and right-hand standby fuel pump switches. 
This proposed AD would also require revising the Emergency and Abnormal 
Procedures sections of the airplane flight manual to advise the 
flightcrew of the proper procedures to follow in the event of failure 
of the standby fuel pump to shut off. This proposed AD results from a 
report of inadvertent operation of a standby fuel pump due to an 
electrical system malfunction. We are proposing this AD to prevent this 
inadvertent operation, which could result in inadvertent fuel transfer 
by the left or right wing fuel system and subsequent over-limit fuel 
imbalance between the left and right wing fuel loads. This imbalance 
could affect lateral control of the airplane which could result in 
reduced controllability.

DATES: We must receive comments on this proposed AD by October 2, 2006.

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.
     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.
    Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, 
for the service information identified in this proposed AD

FOR FURTHER INFORMATION CONTACT: James Galstad, 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) 946-4135; 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 in the ADDRESSES section. Include the docket number ``FAA-2006-
25563; Directorate Identifier 2006-NM-083-AD'' at the beginning 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 received 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 Web site, 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 may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may 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 Docket Management System 
receives them.

Discussion

    We have received a report indicating that inadvertent operation of 
a standby fuel pump due to an electrical system malfunction occurred on 
a Learjet Model 35A (C-21A) airplane. This condition, if not corrected, 
could result in inadvertent fuel transfer by the left or right wing 
fuel system and subsequent over-limit fuel imbalance between the left 
and right wing fuel loads. This imbalance could affect lateral control 
of the airplane which could result in reduced controllability.

Relevant Service Information

    We reviewed the Bombardier service bulletins identified in the 
following table:

[[Page 47155]]



                                               Service Information
----------------------------------------------------------------------------------------------------------------
                                                                                                      Learjet
           Service bulletin                     Revision level                     Date              model(s)
----------------------------------------------------------------------------------------------------------------
23-28-6..............................  Original Issue..................  April 21, 1998.........              23
24/25-28-3...........................  2...............................  February 21, 1998......           24/25
28/29-28-4...........................  3...............................  June 2, 1999...........           28/29
31-28-7..............................  3...............................  January 26, 2001.......              31
35/36-28-11..........................  4...............................  December 4, 2000.......           35/36
55-28-13.............................  3...............................  December 15, 2000......              55
----------------------------------------------------------------------------------------------------------------

The service bulletins describe the following procedures: For airplanes 
on which the replacement of the standby fuel pump switch has been 
accomplished per the original or earlier revisions of the applicable 
referenced service bulletins, the procedures include installing fuses 
and fuse holders, and modifying the electrical wiring. For airplanes on 
which the replacement has not been accomplished per the original issue 
or earlier revisions of the applicable referenced service bulletins, 
the procedures include replacing the standby fuel pump switches, 
installing the fuel pump dimming box assembly, and modifying the 
electrical wiring. The procedures also describe verifying that the 
subject temporary flight manual (TFM) changes have been incorporated 
into the applicable airplane flight manual (AFM).
    We have also reviewed the following Learjet TFM changes:

------------------------------------------------------------------------
                  TFM                                 Date
------------------------------------------------------------------------
TFM 96-08.............................  May 30, 1996.
TFM 96-09.............................  May 30, 1996.
TFM 98-01.............................  May 11, 1999.
TFM 98-02.............................  May 11, 1999.
------------------------------------------------------------------------

The TFMs describe procedures for revising the Emergency and Abnormal 
Procedures sections of the AFM to advise the flightcrew of the proper 
procedures to follow in the event of failure of the standby fuel pump 
to shut off. 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. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 1,613 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD, at an average labor 
rate of $80 per work hour, depending on airplane configuration.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
           Action                Work hours         Parts           Cost per       registered       Fleet cost
                                                                    airplane        airplanes
----------------------------------------------------------------------------------------------------------------
Modification................  Between 4 and    Between $1,426   Between $1,746            1,150  Between
                               12.              and $1,470.      and $2,430.                      $2,007,900 and
                                                                                                  $2,794,500.
AFM Revision................  1..............  None...........  $80............           1,150  $92,000.
----------------------------------------------------------------------------------------------------------------

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 and placed it in the AD docket. 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:


[[Page 47156]]


    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

    2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Learjet: Docket No. FAA-2006-25563; Directorate Identifier 2006-NM-
083-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
2, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the Learjet models identified in the 
applicable Bombardier service bulletin listed in Table 1 of this AD.

                                   Table 1.--Applicability by Service Bulletin
----------------------------------------------------------------------------------------------------------------
         Service bulletin                 Revision level                 Date               Learjet model(s)
----------------------------------------------------------------------------------------------------------------
23-28-6..........................  Original Issue..............  April 21, 1998......  23.
24/25-28-3.......................  2...........................  February 21, 1998...  24, 24A, 24B, 24B-A, 24C,
                                                                                        24D, 24D-A, 24E, 24F,
                                                                                        and 24F-A; 25, 25A, 25B,
                                                                                        25C, 25D, and 25F.
28/29-28-4.......................  3...........................  June 2, 1999........  28 and 29.
31-28-7..........................  3...........................  January 26, 2001....  31 and 31A.
35/36-28-11......................  4...........................  December 4, 2000....  35 and 35A (C-21A); 36
                                                                                        and 36A.
55-28-13.........................  3...........................  December 15, 2000...  55, 55B and 55C.
----------------------------------------------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from a report of inadvertent operation of a 
standby fuel pump due to an electrical system malfunction. We are 
issuing this AD to prevent this inadvertent operation, which could 
result in inadvertent fuel transfer by the left or right wing fuel 
system and subsequent over-limit fuel imbalance between the left and 
right wing fuel loads. This imbalance could affect lateral control 
of the airplane which could result in reduced controllability.

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.

Modification

    (f) Within 24 months after the effective date of this AD: Modify 
the left- and right-hand standby fuel pump switches, in accordance 
with the Accomplishment Instructions of the applicable service 
bulletin identified in Table 1 of this AD.

Airplane Flight Manual (AFM) Revision

    (g) Before further flight after accomplishing the modification 
required by paragraph (f) of this AD: Revise the Emergency and 
Abnormal Procedures sections of the applicable AFM to advise the 
flightcrew of proper procedures to follow in the event of failure of 
the standby fuel pump to shut off by including the information in 
the Learjet temporary flight manual (TFM) Changes identified in 
Table 2 of this AD.

                          Table 2.--TFM Changes
------------------------------------------------------------------------
       Learjet model(s)               TFM                  Date
------------------------------------------------------------------------
24/25, 28/29, 31, 35/35, 55..  TFM 96-08.......  May 30, 1996.
24/25, 28/29, 31, 35/35, 55..  TFM 96-09.......  May 30, 1996.
23...........................  TFM 98-01.......  May 11, 1999.
23...........................  TFM 98-02.......  May 11, 1999.
------------------------------------------------------------------------

This may be done by inserting a copy of the TFM changes into the 
AFM. When the TFM changes have been included in the general 
revisions of the AFM, those general revisions may be inserted into 
the AFM, provided the relevant information in the general revisions 
is identical to that in the TFM changes.

Alternative Methods of Compliance (AMOCs)

    (h)(1) 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.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

    Issued in Renton, Washington, on August 3, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-13453 Filed 8-15-06; 8:45 am]
BILLING CODE 4910-13-P