Document ID: FAA-2021-0660-0002
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Learjet Inc. Airplanes
Posted Date: 2021-12-06T05:00Z

[Federal Register Volume 86, Number 231 (Monday, December 6, 2021)]
[Rules and Regulations]
[Pages 68887-68889]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-26331]

[[Page 68887]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0660; Project Identifier AD-2021-00398-T; 
Amendment 39-21809; AD 2021-23-11]
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. Model 45 airplanes. This AD was prompted by a 
report of a fuel leak due to a cracked fuel line between the engine 
fuel control and the engine fuel flow meter. This AD requires replacing 
the existing fuel flow meter bracket assembly with a redesigned bracket 
assembly and reporting information to the FAA. 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 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. It is also available at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0660.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0660; 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: Thomas Teplik, Aviation Safety 
Engineer, Wichita ACO Branch, FAA, 1801 S. Airport Road, Wichita, KS 
67209; phone: (316) 946-4196; email: [email protected] or [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. 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 August 13, 2021 (86 FR 44660). The NPRM was 
prompted by a report of a fuel leak due to a cracked fuel line between 
the engine fuel control and the engine fuel flow meter on a Model 45 
(Learjet 45) airplane. Further analysis of the fleet of all the 45 
models revealed similar failures in this area including the following: 
16 fuel line failures, 2 instances of multiple inlet attaching bolts 
breaking, 9 leaking fuel controls, a broken gearbox strut, 4 cracked 
No. 6 bearing oil supply lines, and 7 cracked engine oil tanks. The FAA 
evaluated the flammable fluid leaks and broken parts and determined 
that they may have resulted from vibration. In the NPRM, the FAA 
proposed to require replacing the existing fuel flow meter bracket 
assembly with a redesigned bracket assembly and reporting information 
to the FAA. The FAA is issuing this AD to address the unsafe condition 
on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received no comments on the NPRM or on the determination of 
the costs.

Conclusion

    The FAA reviewed the relevant data 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. This AD is 
adopted as proposed in the NPRM.

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 (SB) SB 40-73-01, 
Revision 1;
     Bombardier Learjet 45 SB 45-73-2, Revision 1;
     Bombardier Learjet 70 SB 70-73-01, Revision 1; and
     Bombardier Learjet 75 SB 75-73-01, Revision 2; all 
documents dated January 9, 2017.
    As applicable to the model configuration specified, each service 
bulletin contains procedures for replacing the existing fuel flow meter 
bracket assembly with a redesigned fuel flow meter bracket assembly 
that has an increased material thickness. 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 
ADDRESSES.

Differences Between This AD and the Service Information

    This AD requires reporting certain maintenance information to the 
FAA, where the service information does not. The information provided 
in the reports is related to contributing factors that the FAA found 
showed a correlation between the reported engine fan vibration levels 
and the cracking fuel line between engine fuel control and the engine 
fuel flow meter and a correlation between the cracking fuel line and a 
certain batch of fan disks. In addition, the FAA found that a 
contributing factor could be the susceptibility of the fuel flow meter 
bracket assembly to the engine installation vibration. The requested 
reporting information allows the FAA to determine whether further 
rulemaking action is necessary to mitigate the unsafe condition.
    Also, the effectivity of Bombardier Learjet 45 SB 45-73-2, Revision 
1, dated January 9, 2017, begins with serial number 45-005. This AD 
also applies to airplane serial numbers 45-002 through 45-004 because, 
although these three airplanes are not currently in service, they are 
subject to the unsafe condition. Thus, it is necessary to include them 
in the event they are returned to service.

Costs of Compliance

    The FAA estimates that this AD affects 443 airplanes of U.S. 
registry.
    The FAA estimates the following costs to comply with this AD:

[[Page 68888]]

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
              Action                      Labor cost             Parts Cost           product        operators
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Replacing the bracket assembly....  4.5 work-hours x $85   $3,895...............       $4,277.50   $1,894,932.50
                                     per hour = $382.50.
Reporting and reviewing logbooks..  9 work-hours x $85     Not Applicable.......             765         338,895
                                     per hour = $765.
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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 9 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.
    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:

2021-23-11 Learjet Inc.: Amendment 39-21809; Docket No. FAA-2021-
0660; Project Identifier AD-2021-00398-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 45-556 and 45-2001 through 
45-2146, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7100, Powerplant 
System.

(e) Unsafe Condition

    This AD was prompted by a report of a fuel leak due to a cracked 
fuel line between the engine fuel control and the engine fuel flow 
meter. The FAA is issuing this AD to prevent cracking and failures. 
The unsafe condition, if not addressed, could result in an engine 
installation fire, which could progress to an uncontrolled fire and 
consequent loss of control of the airplane.

(f) Compliance

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

(g) Reporting Requirement

    Within 60 days after the effective date of this AD, report the 
following information, where available, to the Wichita ACO Branch 
via email at [email protected] and [email protected]; or by 
mail to Wichita ACO Branch, FAA, Attn: Thomas Teplik, 1801 S. 
Airport Road, Room 100, Wichita, KS 67209.
    (1) Name of the owner; the address of the owner; name of the 
organization doing the actions required by this AD; the date the 
actions were completed; the name of the person submitting the 
report; the address, telephone number, and email of the person 
submitting the report.
    (2) The fan vibration levels that have been recorded in the 
airplane and engine maintenance records since November 1, 2019. 
Include the airplane and engine serial numbers.
    (3) The date of each vibration level recorded and the associated 
hours time-in-service (TIS) for the airplane and each engine.
    (4) For each fan vibration level reported, include:
    (i) Whether molybdenum coating for the fan was applied per 
Temporary Revision 72-494, dated August 15, 2017 (or as subsequently 
incorporated into the engine's Inspection/Repair Manual TFE731 (ATA 
Number 72-IR-02)).
    (ii) If molybdenum coating was applied using a different process 
than Temporary Revision 72-494, dated August 15, 2017 (or as 
subsequently incorporated into the engine's Inspection/Repair Manual 
TFE731 (ATA Number 72-IR-02)), report the process by which the 
molybdenum coating was applied and the revision level of the

[[Page 68889]]

document defining the application process for the molybdenum 
coating.
    Note 1 to paragraph (g)(4): Temporary Revision 72-494, dated 
August 15, 2017, specifies applying a dry film lubricant on the 
mating surfaces of the fan hub and the fan blades. The lubricating 
solid for this dry film lubricant is molybdenum disulfide, which is 
referred to in this AD as molybdenum coating.
    (5) For each fan vibration level reported, the fan hub serial 
number and hours TIS for this fan hub.
    (6) Installation date and service bulletin (SB) revision level 
for the installation of the bracket assembly with fuel flow meter 
and hose if installed before the effective date of this AD.
    (7) Any failures of the bracket assembly with fuel flow meter 
and hose installed in accordance with any SB listed in paragraph (h) 
of this AD or any prior revision of these SBs.
    (8) Installation date and SB revision level used for 
installation of the fuel control screws within the engine fuel 
control in accordance with Honeywell SB TFE731-73-5146.
    (9) Any failures of fuel control screws after compliance with 
Honeywell SB TFE731-73-5146.

(h) Replacement

    Within 12 months after the effective date of this AD or 750 
hours TIS after the effective date of this AD, whichever occurs 
first, replace the engine fuel flow meter bracket in accordance with 
the Accomplishment Instructions, paragraphs 3.A through 3.C, of the 
following Bombardier SB, listed in paragraphs (h)(1) through (4) of 
this AD, applicable to your airplane model configuration.
    (1) Bombardier Learjet 40 SB 40-73-01, Revision 1, dated January 
9, 2017.
    (2) Bombardier Learjet 45 SB 45-73-2 Revision 1, dated January 
9, 2017.
    (3) Bombardier Learjet 70 SB 70-73-01 Revision 1, dated January 
9, 2017.
    (4) Bombardier Learjet 75 SB 75-73-01, Revision 2, dated January 
9, 2017.

(i) Credit for Previous Actions

    (1) This paragraph provides credit for the action required by 
paragraph (h) of this AD, if that action was performed before the 
effective date of this AD using Bombardier Learjet 40 SB 40-73-01, 
Basic Issue; Bombardier Learjet 45 Service Bulletin SB 45-73-2, 
Basic Issue; Bombardier Learjet 70 SB 70-73-01, Basic Issue; or 
Bombardier Learjet 75 SB 75-73-01, Basic Issue; all dated October 3, 
2016; or Bombardier Learjet 75 SB 75-73-01, Revision 1, dated 
October 10, 2016.
    (2) To take credit for any previous action, you must comply with 
paragraph (g) of this AD within 60 days after the effective date of 
this AD.

(j) 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 (k) 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.

 (k) Related Information

    For more information about this AD, contact Thomas Teplik, 
Aviation Safety Engineer, Wichita ACO Branch, FAA, 1801 S. Airport 
Road, Wichita, KS 67209; phone: (316) 946-4196; email: 
[email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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 40-73-01, Revision 1, 
dated January 9, 2017.
    (ii) Bombardier Learjet 45 Service Bulletin 45-73-2 Revision 1, 
dated January 9, 2017.
    (iii) Bombardier Learjet 70 Service Bulletin 70-73-01 Revision 
1, dated January 9, 2017.
    (iv) Bombardier Learjet 75 Service Bulletin 75-73-01, Revision 
2, dated January 9, 2017.
    (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: https://businessaircraft.bombardier.com/en/aircraft/Learjet.html.
    (4) You may view this 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.
    (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 November 1, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-26331 Filed 12-3-21; 8:45 am]
BILLING CODE 4910-13-P