Airworthiness Directives; Learjet Model 23, 24, 25, 35, and 36 Airplanes

[Federal Register Volume 70, Number 152 (Tuesday, August 9, 2005)]
[Rules and Regulations]
[Pages 46069-46072]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-15585]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20798; Directorate Identifier 2004-NM-257-AD; 
Amendment 39-14214; AD 2005-16-09]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 23, 24, 25, 35, and 36 
Airplanes

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

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to certain Learjet Model 23, 24, 25, 35, and 36 
airplanes. That AD currently requires repetitive inspections to detect 
deterioration of both flappers of the tip tank in each wing of the 
airplane, and various follow-on actions. The existing AD also requires 
replacing the flappers with new flappers, and repetitively performing 
certain other follow-on actions. This new AD requires an inspection of 
the flappers and flapper assemblies of the tip tank in each wing or a 
review of the

[[Page 46070]]

airplane maintenance records to determine the part numbers, and 
replacement of certain flappers or flapper assemblies if necessary, 
which ends the existing repetitive inspections. This AD results from 
numerous continual inspections and the approval of a new, improved 
flapper and flapper assembly. We are issuing this AD to prevent 
significant reduction in the lateral control of the airplane due to 
imbalance of the fuel loads in the wings of the airplane.

DATES: Effective September 13, 2005.
    The Director of the Federal Register approved the incorporation by 
reference of Bombardier Service Bulletin SB 23/24/25-28-7, Revision 2, 
dated May 9, 2001; and Bombardier Service Bulletin SB 35/36-28-14, 
Revision 2, dated May 9, 2001; as of September 13, 2005.
    On December 27, 1995 (60 FR 63617, December 12, 1995), the Director 
of the Federal Register approved the incorporation by reference of 
Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995; and 
Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995.

ADDRESSES: You may examine the 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., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, 
for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Jeffrey Janusz, 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) 946-4148; fax (316) 
946-4107.

SUPPLEMENTARY INFORMATION:

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 street address stated in the 
ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that supersedes AD 95-25-03, amendment 39-
9447 (60 FR 63617, December 12, 1995). The existing AD applies to 
certain Learjet Model 23, 24, 25, 35, and 36 airplanes. That NPRM was 
published in the Federal Register on April 4, 2005 (70 FR 16984). That 
NPRM proposed to require repetitive inspections to detect deterioration 
of both flappers of the tip tank in each wing of the airplane, and 
various follow-on actions. That NPRM also proposed to require replacing 
the flappers with new flappers, and repetitively performing certain 
other follow-on actions. In addition, that NPRM proposed to require an 
inspection of the flappers and flapper assemblies of the tip tank in 
each wing or a review of the airplane maintenance records to determine 
the part numbers, and replacement of certain flappers or flapper 
assemblies if necessary, which ends the existing repetitive 
inspections.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. No comments have been received on the NPRM or 
on the determination of the cost to the public.

Change to Certain Service Bulletin References

    We have revised the NPRM to correct the airplane manufacturer's 
name from ``Learjet'' to ``Bombardier'' in the title of the following 
referenced service bulletins: Bombardier Service Bulletin 23/24/25-28-
7, Revision 2, dated May 9, 2001; and Bombardier Service Bulletin 35/
36-28-14, Revision 2, dated May 9, 2001.

Conclusion

    We have carefully reviewed the available data and determined that 
air safety and the public interest require adopting the AD with the 
change described previously. We have determined that this change will 
neither increase the economic burden on any operator nor increase the 
scope of the AD.

Costs of Compliance

    There are about 1,459 airplanes of the affected design in the 
worldwide fleet. This AD will affect about 882 airplanes of U.S. 
registry.
    The actions that are required by AD 95-25-03 and retained in this 
AD take about 16 work hours per airplane, at an average labor rate of 
$65 per work hour. Required parts cost about $708 per airplane. Based 
on these figures, the estimated cost of the currently required actions 
is $1,541,736, or $1,748 per airplane.
    The new actions will take about 2 work hours per airplane, at an 
average labor rate of $65 per work hour. Required parts will cost about 
$327 or $1,262 per airplane (depending on the kit installed). Based on 
these figures, the estimated cost of the new actions specified in this 
AD for U.S. operators is $457 or $1,392, per airplane (depending on the 
kit installed).

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 AD will not have federalism 
implications under Executive Order 13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator,

[[Page 46071]]

the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-9447 (60 FR 63617, December 12, 1995) and by 
adding the following new airworthiness directive (AD):

2005-16-09 Learjet: Amendment 39-14214. Docket No. FAA-2005-20798; 
Directorate Identifier 2004-NM-257-AD.

Effective Date

    (a) This AD becomes effective September 13, 2005.

Affected ADs

    (b) This AD supersedes AD 95-25-03, amendment 39-9447.

Applicability

    (c) This AD applies to the airplanes in Table 1 of this AD, 
certificated in any category.

                                             Table 1.--Applicability
----------------------------------------------------------------------------------------------------------------
               Learjet--                                             Serial numbers--
----------------------------------------------------------------------------------------------------------------
Model 23 airplanes.....................  23-003 through 23-090 inclusive.
Model 24 airplanes.....................  24-100 through 24-357 inclusive.
Model 25 airplanes.....................  25-002 through 25-373 inclusive.
Model 35 airplanes.....................  35-002 through 35-676 inclusive.
Model 36 airplanes.....................  36-002 through 36-063 inclusive.
----------------------------------------------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from numerous continual inspections and the 
approval of a new, improved flapper and flapper assembly. We are 
issuing this AD to prevent significant reduction in the lateral 
control of the airplane due to imbalance of the fuel loads in the 
wings 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.

Requirements of AD 95-25-03

Repetitive Inspections, Related Investigative Actions, and Replacement

    (f) Within 50 hours time-in-service after December 27, 1995 (the 
effective date of AD 95-25-03), or prior to the accumulation of 600 
hours time-in-service since installation of the flapper valve, 
whichever occurs later: Perform an inspection to detect 
deterioration (such as cracks, cuts, breaks, splits, or warpage) of 
both flappers of the tip tank in each wing, in accordance with 
either Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 
1995 (for Model 23, 24, and 25 airplanes); or Learjet Service 
Bulletin SB 35/36-28-10, dated October 6, 1995 (for Model 35 and 36 
airplanes); as applicable. Repeat this inspection thereafter at 
intervals not to exceed 600 hours time-in-service.
    (1) If no deterioration of the flapper valve is detected, prior 
to further flight, inspect the flapper valve to ensure proper 
positioning, inspect the condition of the screws that retain the 
flapper valve to the plate assembly to ensure that the flapper valve 
is secure, inspect to ensure that the flapper valve completely 
covers the opening of the tube and is seated against the tube, and 
inspect the flapper valve to verify that it moves freely; and 
accomplish the follow-on corrective actions, if any discrepancy is 
found. These actions shall be accomplished in accordance with the 
applicable service bulletin.
    (2) If any flapper valve is found to be deteriorated, prior to 
further flight, replace it with a new flapper valve in accordance 
with the applicable service bulletin.
    (g) Except as provided in paragraph (h) of this AD, at the later 
of the times specified in paragraphs (g)(1) and (g)(2) of this AD: 
Replace both flappers of the tip tank in each wing with new flappers 
in accordance with either Learjet Service Bulletin SB 23/24/25-28-2, 
dated October 6, 1995 (for Model 23, 24, and 25 airplanes); or 
Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995 (for 
Model 35 and 36 airplanes); as applicable.
    (1) Within 5 years since date of installation of the flapper 
valve, or prior to the accumulation of 2,400 total hours time-in-
service on the flapper valve, whichever occurs earlier.
    (2) Within 50 hours time-in-service after December 27, 1995.
    (h) For airplanes on which the age and time-in-service of the 
flapper valve cannot be determined: Within 50 hours time-in-service 
after December 27, 1995, replace both flappers of the tip tank in 
each wing in accordance with either Learjet Service Bulletin SB 23/
24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25 
airplanes); or Learjet Service Bulletin SB 35/36-28-10, dated 
October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
    (i) Within 600 hours time-in-service following replacement of 
any flapper valve in accordance with the requirements of this AD, 
and thereafter at intervals not to exceed 600 hours time-in-service: 
Accomplish the requirements of paragraph (f) of this AD.

New Requirements of This AD

Inspection and Replacement

    (j) Within 600 hours time-in-service since last replacement of 
any flapper valve in accordance with the requirements of this AD, or 
within 90 days after the effective date of this AD, whichever occurs 
later, inspect the flappers and flapper assemblies of the tip tank 
in each wing to determine their part numbers (P/N). The raised 
letter and numbers ``S-461'' on the convex side of the flappers can 
identify these parts. Instead of inspecting the flappers and flapper 
assemblies, a review of airplane maintenance records is acceptable 
if the P/N of the flappers and flapper assemblies can be 
conclusively determined from that review.
    (1) If four flappers having P/N 2323006-802 and four flapper 
assemblies having P/N 2323006-801 are found installed, no further 
action is required by this paragraph, and the repetitive inspections 
required by paragraphs (f) and (i) of this AD can be stopped.
    (2) If any flapper having P/N 2323006-5 or any flapper assembly 
having P/N 2323006-6 is found installed, within 600 hours time-in-
service since last replacement of any flapper valve in accordance 
with the requirements of this AD, replace the flapper valve with a 
new flapper valve or replace the flapper assembly with new or 
modified and reidentified assembly, as applicable. The replacement 
must be done in accordance with the Accomplishment Instructions of 
Bombardier Service Bulletin SB 23/24/25-28-7, Revision 2, dated May 
9, 2001 (for Model 23, 24, and 25 airplanes); or Bombardier Service 
Bulletin SB 35/36-28-14, Revision 2, dated May 9, 2001 (for Model 35 
and 36 airplanes); as applicable. Accomplishment of the replacement 
ends the repetitive inspections required by paragraphs (f) and (i) 
of this AD.

Parts Installation

    (k) As of the effective date of this AD, no person may install a 
flapper having P/N 2323006-5 or a flapper assembly having P/N 
2323006-6, on any airplane.

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Wichita Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) AMOCs approved previously according to AD 95-25-03 are not 
approved as AMOCs with this AD.

Material Incorporated by Reference

    (m) You must use the applicable service bulletins identified in 
Table 2 of this AD to perform the actions that are required by this 
AD, unless the AD specifies otherwise.

[[Page 46072]]

    (1) The Director of the Federal Register approved the 
incorporation by reference of Bombardier Service Bulletin SB 23/24/
25-28-7, Revision 2, dated May 9, 2001; and Bombardier Service 
Bulletin SB 35/36-28-14, Revision 2, dated May 9, 2001; in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) On December 27, 1995 (60 FR 63617, December 12, 1995), the 
Director of the Federal Register approved the incorporation by 
reference of Learjet Service Bulletin SB 23/24/25-28-2, dated 
October 6, 1995; and Learjet Service Bulletin SB 35/36-28-10, dated 
October 6, 1995.
    (3) Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 
67209-2942, for a copy of this service information. You may review 
copies at the Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW., Room PL-401, Nassif 
Building, Washington, DC; on the Internet at http://dms.dot.gov; or 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at the NARA, call 
(202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

                                  Table 2.--Material Incorporated by Reference
----------------------------------------------------------------------------------------------------------------
           Service bulletin                        Revision level                            Date
----------------------------------------------------------------------------------------------------------------
Bombardier Service Bulletin SB 23/24/   2..................................  May 9, 2001.
 25-28-7.
Bombardier Service Bulletin SB 35/36-   2..................................  May 9, 2001.
 28-14.
Learjet Service Bulletin SB 23/24/25-   Original...........................  October 6, 1995.
 28-2.
Learjet Service Bulletin SB 35/36-28-   Original...........................  October 6, 1995.
 10.
----------------------------------------------------------------------------------------------------------------


    Issued in Renton, Washington, on July 29, 2005.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-15585 Filed 8-8-05; 8:45 am]
BILLING CODE 4910-13-P

The complete text was extracted from the official GovInfo HTML edition for this publication. Acquired 2026-10-09T03:53:16.293835+00:00. Text extraction preserves the recorded source wording; it does not determine current requirements.

Open the captured official edition

Source SHA-256

80e742a49451468f14fa2790b252792a7d35079ea02babcf6247e904be56b135

Text SHA-256

3965e37cf641572863f62a054252d1e0fb7523cfe1ec1d4389eb7384a0585fc0