[Federal Register Volume 86, Number 231 (Monday, December 6, 2021)]
[Rules and Regulations]
[Pages 68899-68902]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-26330]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0157; Project Identifier AD-2020-00483-T; 
Amendment 39-21806; AD 2021-23-08]
RIN 2120-AA64


Airworthiness Directives; Learjet Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Learjet Inc. (Learjet) Model 45 airplanes. This AD was prompted 
by reports of corrosion found on the upper surface of the lower center 
wing mid spar splice plate. This AD requires repetitively inspecting 
the center wing area for corrosion and deterioration of protective 
treatments, removing any corrosion, and treating any deteriorated 
areas. The FAA is issuing this AD to address the unsafe condition on 
these products.

DATES: This AD is effective January 10, 2022.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of January 10, 
2022.

ADDRESSES: For service information identified in this final rule, 
contact Learjet Inc., One Learjet Way, Wichita, KS 67209; phone: (316) 
946-2000; email: [email protected]; website: https://
businessaircraft.bombardier.com/en/aircraft/learjet.html. You may view 
this referenced service information at the FAA, Airworthiness Products 
Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. 
For information on the availability of this material at the FAA, call 
(816) 329-4148.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0157; or in person at 
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The AD docket contains this final rule, any 
comments received, and other information. The address for Docket 
Operations is U.S. Department of Transportation, Docket Operations, M-
30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue 
SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Tara Shawn, Aviation Safety Engineer, 
Wichita ACO Branch, FAA, 1801 Airport Road, Wichita, KS 67209; phone: 
(316) 946-4141; fax: (316) 946-4107; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain serial numbered 
Learjet Inc. (Learjet) Model 45 (Learjet 40), Model 45 (Learjet 45), 
Model 45 (Learjet 70), and Model 45 (Learjet 75) airplanes. The NPRM 
published in the Federal Register on July 28, 2021 (86 FR 40379). The 
NPRM was prompted by a report from Learjet of corrosion found in the 
center wing area of a Model 45 (Learjet 45) airplane. Exfoliating 
corrosion was found on the upper surface of the lower center wing mid 
spar splice plate during unrelated maintenance. The corrosion appeared 
to extend half way through the thickness of the splice plate. Since the 
initial report, the FAA has received 23 additional reports of corrosion 
from Learjet.
    The FAA determined areas of the wing center section are not sealed 
against the elements; in addition, the fuselage has drain holes that 
allow condensation to drain into the center wing. The accumulation and 
retention of moisture in the center wing section may lead to corrosion. 
In the NPRM, the FAA proposed to require repetitively inspecting the 
center wing area for corrosion and deterioration of protective 
treatments, removing any corrosion, and treating any deteriorated 
areas. This

[[Page 68900]]

condition, if not addressed, could result in failure of the wing 
centerline joint and lead to partial wing separation with consequent 
loss of control of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received one comment from an individual. The following 
presents the comment received on the NPRM and the FAA's response to the 
comment.
    An individual requested the FAA allow credit for previous visual 
inspections using Inspection Reference Number (IRN) 5710190. The 
commenter stated that IRN 5710190 requires the same inspection as the 
applicable service bulletin. The commenter noted that while some 
operators might not have used the service bulletin listed in paragraph 
(k) of the NPRM, operators of aircraft over 8 years old will have used 
IRN 5710190.
    The FAA agrees and has added the applicable maintenance manual 
references for IRN 5710190 to paragraph (k) of this AD, which provides 
credit for previous actions.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for the changes described 
previously, this AD is adopted as proposed in the NPRM. None of the 
changes will increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed the following service documents required for 
compliance with this AD:
     Bombardier Learjet 40 Service Bulletin 40-57-06, Revision 
1, dated October, 26, 2020;
     Bombardier Learjet 45 Service Bulletin 45-57-13, Revision 
1, dated October, 26, 2020;
     Bombardier Learjet 70 Service Bulletin 70-57-02, Revision 
1, dated October, 26, 2020; and
     Bombardier Learjet 75 Service Bulletin 75-57-01, Revision 
2, dated April 19, 2021.
    As applicable to the model configuration specified, each service 
bulletin contains procedures for inspecting for corrosion and 
deterioration of protective treatments of the center wing area from the 
front spar to the rear spar between wing stations 33.00L to 33.00R, 
treating deteriorated areas, and removing any corrosion. Bombardier 
Learjet 75 Service Bulletin 75-57-01, Revision 2, dated April 19, 2021, 
does not apply to newly- manufactured airplanes, since Learjet added 
this inspection to the Airworthiness Limitation Section, which will be 
delivered with new airplanes starting at S/N 45-597.
    This service information is reasonably available because the 
interested parties have access to it through their normal course of 
business or by the means identified in the ADDRESSES.

Costs of Compliance

    The FAA estimates that this AD affects 450 airplanes of U.S. 
registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
              Action                      Labor cost             Parts Cost           product        operators
----------------------------------------------------------------------------------------------------------------
Inspect...........................  7.5 work-hours x $85   Not applicable.......         $637.50        $286,875
                                     per hour = $637.50.
Report to FAA.....................  1 work-hours x $85     Not applicable.......              85          38,250
                                     per hour = $85.
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    The extent of corrosion and deterioration of protective treatments 
may vary significantly from airplane to airplane. The FAA has no way of 
determining how much damage may be found on each airplane, the cost to 
remove the corrosion or treat deteriorated areas (or replacing the 
part, if needed), or the number of airplanes that may require repair.
    If corrosion is found and removed, the FAA estimates that it would 
take 2 work-hours per airplane to provide data to Learjet. With an 
average labor rate of $85 per work-hour, the FAA estimates a cost of 
$170 per airplane.

Paperwork Reduction Act

    A federal agency may not conduct or sponsor, and a person is not 
required to respond to, nor shall a person be subject to a penalty for 
failure to comply with a collection of information subject to the 
requirements of the Paperwork Reduction Act unless that collection of 
information displays a currently valid OMB Control Number. The OMB 
Control Number for this information collection is 2120-0056. Public 
reporting for this collection of information is estimated to take 
approximately 3 hours per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information. All responses to this collection of 
information are mandatory. Send comments regarding this burden estimate 
or any other aspect of this collection of information, including 
suggestions for reducing this burden to: Information Collection 
Clearance Officer, Federal Aviation Administration, 10101 Hillwood 
Parkway, Fort Worth, TX 76177-1524.

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.
    The FAA is 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

    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.

[[Page 68901]]

    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, 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 FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:
    2021-23-08 Learjet Inc.: Amendment 39-21806; Docket No. FAA-
2021-0157; Project Identifier AD-2020-00483-T.

(a) Effective Date

    This airworthiness directive (AD) is effective January 10, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Learjet Inc. Model 45 (Learjet 40), Model 45 
(Learjet 45), Model 45 (Learjet 70), and Model 45 (Learjet 75) 
airplanes, serial numbers 45-002 through 45-596 and 45-2001 through 
45-2146, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) Code 5714, Wing, Center 
Box.

(e) Unsafe Condition

    This AD was prompted by reports of corrosion found on the upper 
surface of the lower center wing mid spar splice plate. The FAA is 
issuing this AD to detect and correct corrosion or deterioration of 
protective treatments on the center wing area. The unsafe condition, 
if not addressed, could result in failure of the wing centerline 
joint and lead to partial wing separation with consequent loss of 
control of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Applicable Service Bulletins

    Use the following service bulletin, as applicable to your 
airplane model configuration, to perform the actions required by 
paragraph (h) of this AD:
    (1) Bombardier Learjet 40 Service Bulletin 40-57-06, Revision 1, 
dated October 26, 2020;
    (2) Bombardier Learjet 45 Service Bulletin 45-57-13, Revision 1, 
dated October 26, 2020;
    (3) Bombardier Learjet 70 Service Bulletin 70-57-02, Revision 1, 
dated October 26, 2020; or
    (4) Bombardier Learjet 75 Service Bulletin 75-57-01, Revision 2, 
dated April 19, 2021.

(h) Wing Center Spar Inspection, Related Investigative Inspections, and 
Corrective Actions

    At the applicable initial compliance time specified in paragraph 
(h)(1) or (2) of this AD and thereafter at intervals not to exceed 8 
years, inspect the center wing area for corrosion and deterioration 
of protective treatments and perform all related corrective actions 
by following the Accomplishment Instructions, steps 3.A. and 3.B., 
of the applicable service bulletin listed in paragraph (g) of this 
AD.
    (1) For airplanes with 8 or fewer years since the date of 
issuance of the original airworthiness certificate or the date of 
issuance of the original export certificate of airworthiness, 
whichever date is earlier: Before or upon accumulating 8 years or 
within 12 months after the effective date of this AD, whichever 
occurs later; or
    (2) For airplanes that have accumulated more than 8 years since 
the date of issuance of the original airworthiness certificate or 
the date of issuance of the original export certificate of 
airworthiness, whichever date is earlier: Within 12 months after the 
effective date of this AD.

(i) Service Information Exception

    Where Bombardier Learjet 40 Service Bulletin 40-57-06, Revision 
1, dated October 26, 2020, Bombardier Learjet 45 Service Bulletin 
45-57-13, Revision 1, dated October 26, 2020, Bombardier Learjet 70 
Service Bulletin 70-57-02, Revision 1, dated October 26, 2020, and 
Bombardier Learjet 75 Service Bulletin 75-57-01, Revision 2, dated 
April 19, 2021, specify contacting Learjet Inc. for appropriate 
action: Before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (l) of this 
AD.

(j) Reporting Requirement

    Within 30 days after completing the initial inspection required 
by paragraph (h) of this AD or within 30 days after the effective 
date of this AD, whichever occurs later, submit a report of the 
findings (both positive and negative) of the inspection to: [email protected]; or Ann Johnson, Wichita ACO Branch, FAA, 1801 Airport 
Road, Wichita, KS 67209. This reporting requirement is limited to 
the initial inspection results only. The report must include: The 
name of the owner; the address of the owner; the name of the 
organization doing the actions required by this AD; the date the 
inspection was completed; the name of the person submitting the 
report; the address, telephone number, and email of the person 
submitting the report; the airplane serial number; the date of 
issuance of the original airworthiness certificate, or the date of 
issuance of the original export certificate of airworthiness 
(whichever date is earlier); whether protective treatments are 
deteriorated, and if so, the location of deteriorated areas; whether 
corrosion was detected, and if so, the location of corrosion; and a 
list of parts replaced if the level of corrosion required 
replacement of parts.

(k) Credit for Previous Actions

    You may take credit for the initial wing spar inspection 
required by the introductory text to paragraph (h) of this AD if you 
performed the visual inspection before the effective date of this AD 
using Bombardier Learjet 40 Service Bulletin 40-57-06, Basic Issue, 
dated February 25, 2019; Bombardier Learjet 40 Maintenance Manual 
MM-105, Temporary Revision No. 4-32, Inspection Reference Number 
AC5710190, dated March 25, 2021; Bombardier Learjet 40 Maintenance 
Manual MM-105, Inspection Reference Number AB5710190, dated April 
29, 2019, or November 14, 2019; Bombardier Learjet 45 Service 
Bulletin 45-57-13, Basic Issue, dated February 25, 2019; Bombardier 
Learjet 45 Maintenance Manual MM-104, Temporary Revision No. 4-47, 
Inspection Reference Number AC5710190, dated March 25, 2021; 
Bombardier Learjet 45 Maintenance Manual MM-104, Inspection 
Reference Number AB5710190, dated April 29, 2019, or November 14, 
2019; Bombardier Learjet 70 Service Bulletin 70-57-02, Basic Issue, 
dated February 25, 2019; Bombardier Learjet 70/75 eINSPECTOR version 
(2019.2.25) thru version (2021.4.23), Inspection Reference Number 
5710190; Bombardier Learjet 75 Service Bulletin 75-57-01, Basic 
Issue, dated February 25, 2019; or Bombardier Learjet 75 Service 
Bulletin 75-57-01, Revision 1, dated October 26, 2020.
    (1) To take credit for the initial inspection, you must comply 
with paragraph (j) of this AD within 30 days after the effective 
date of this AD.
    (2) You cannot take credit for the recurring inspections, only 
the initial inspection.

(l) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Wichita ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (m) of this AD.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this

[[Page 68902]]

AD if it is approved by a Learjet Inc. Designated Engineering 
Representative, or a Unit Member of the Learjet Organization 
Designation Authorization, that has been authorized by the Manager, 
Wichita ACO Branch, to make those findings. To be approved, the 
repair, modification, or alteration method must meet the 
certification basis of the airplane, and the approval must 
specifically refer to this AD.

(m) Related Information

    For more information about this AD, contact Tara Shawn, Aviation 
Safety Engineer, Wichita ACO Branch, FAA, 1801 Airport Road, 
Wichita, KS 67209; phone: (316) 946-4141; fax: (316) 946-4107; 
email: [email protected].

(n) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Bombardier Learjet 40 Service Bulletin 40-57-06, Revision 1, 
dated October, 26, 2020.
    (ii) Bombardier Learjet 45 Service Bulletin 45-57-13, Revision 
1, dated October, 26, 2020.
    (iii) Bombardier Learjet 70 Service Bulletin 70-57-02, Revision 
1, dated October, 26, 2020.
    (iv) Bombardier Learjet 75 Service Bulletin 75-57-01, Revision 
2, dated April 19, 2021.
    (3) For service information identified in this AD, contact 
Learjet Inc., One Learjet Way, Wichita, KS 67209; phone: (316) 946-
2000; email: [email protected]; website: 
businessaircraft.bombardier.com/en/aircraft/learjet.html.
    (4) You may view this service information at FAA, Airworthiness 
Products Section, Operational Safety Branch, 901 Locust, Kansas 
City, MO 64106. For information on the availability of this material 
at the FAA, call (816) 329-4148.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email: [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on October 28, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-26330 Filed 12-3-21; 8:45 am]
BILLING CODE 4910-13-P