Airworthiness Directives; Learjet Inc. Airplanes

[Federal Register Volume 85, Number 99 (Thursday, May 21, 2020)]
[Rules and Regulations]
[Pages 30837-30840]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-10915]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0204; Project Identifier 2018-CE-042-AD; Amendment 
39-21129; AD 2020-11-04]
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 60 airplanes. This AD was prompted by a 
report of a reverse thrust command accelerating the airplane instead of 
decelerating the airplane. The acceleration with reverse thrust 
commanded occurred when the thrust reverser doors were in the stowed 
position instead of the deployed position. This AD requires installing 
a thrust reverser (T/R) Voice Command Warning System (VCWS) to alert 
the crew of a T/R malfunction. The FAA is

[[Page 30838]]

issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective June 25, 2020.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of June 25, 
2020.

ADDRESSES: For service information identified in this final rule, 
contact Learjet Inc., MS 53, P.O. Box 7707, Wichita, Kansas 67277-7707; 
telephone: (toll free) 1-866-538-1247; (514) 855-2999; internet: 
https://my.businessaircraft.bombardier.com. You may view this service 
information at the FAA, Airworthiness Products Section, Operational 
Safety Branch, 901 Locust, Kansas City, Missouri 64106. For information 
on the availability of this material at the FAA, call (816) 329-4148. 
It is also available on the internet at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2019-0204.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2019-
0204; 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 Docket Operations, 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: James Galstad, Aerospace Engineer, 
Wichita ACO Branch, 1801 Airport Road, Room 100, Wichita, Kansas 67209; 
telephone: (316) 946-4135; fax: (316) 946-4107; email: 
[email protected] or [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    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 60 airplanes. The NPRM published in the Federal 
Register on May 13, 2019 (84 FR 20823). The NPRM was prompted by a 
report of a high-speed rejected takeoff involving a Learjet Model 60 
airplane that occurred when all four main landing gear (MLG) tires blew 
out during the takeoff roll. The tires blew out due to internal heat 
damage consistent with under-inflation, overloading, or a combination 
of both. Subsequently, damage from tires caused damage to various 
components, including the MLG squat switches, brake hydraulic tubes, 
wheel speed sensor wiring, and anti-skid components. In the event of 
squat switch wiring failures, thrust reverser operation can be 
adversely affected. During the subject accident, forward thrust 
occurred when the thrust reverser doors stowed due to the failure, and 
at the same time the crew was still commanding reverse thrust. Squat 
switch wiring can also be damaged by other external factors, such as 
bird strikes or deer strikes.
    The FAA considers this AD to be the third of three related ADs that 
collectively address unsafe conditions that might result from damage to 
critical components on the landing gear or in the wheel well that 
affect the braking, spoiler, and thrust reverser systems. AD 2010-11-
11, Amendment 39-16316 (75 FR 32255, June 8, 2010) was issued to 
prevent tire failure, and AD 2013-13-09, Amendment 39-17497 (78 FR 
39574, July 2, 2013) was issued to prevent failure of the braking 
system or adverse operation of the spoiler and reverse thruster system 
due to external damage, particularly from tire failure, which could 
result in loss of control of the airplane.
    The NPRM proposed to require installing a T/R VCWS to alert the 
crew of a T/R malfunction. The FAA is issuing this AD to mitigate 
failure of the engine thrust reverser system. The unsafe condition, if 
not addressed, could result in the airplane overrunning the runway or a 
runway excursion.

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Support for the NPRM

    The National Transportation Safety Board (NTSB) and Damian Palaich 
expressed support for the NPRM.

Request To Withdraw the NPRM

    Charles Perrigoue requested that the NPRM be withdrawn. The 
commenter noted that modern aircraft designs have shifted away from a 
multitude of aural alarms and warnings and that most modern business 
jets and airline aircraft suppress alarms during critical phases of 
flight. The commenter stated there is no nexus between the proposed AD 
actions and the precipitating Learjet Model 60 accident, as the pilot 
correctly recognized and reacted to the thrust reverser malfunction.
    The FAA disagrees with the commenter's request. The design change 
required by paragraph (g) of this AD incorporates a direct aural voice 
command for a rapid effective response and design features to minimize 
faulty voice commands. The FAA's evaluation concludes that the 
installation of the T/R VCWS required by this AD will effectively 
mitigate the identified unsafe condition and prevent future scenarios 
similar to the September 19, 2008, accident involving a Learjet Model 
60 airplane. The T/R VCWS is monitoring the thrust reversers and 
providing a voice command, when needed, which will enable a faster 
pilot response to decelerate the airplane. The FAA has not changed this 
AD in this regard.

Request To Incorporate a Solution That Is Not Reliant on Crew Action

    An anonymous commenter stated the proposed AD does not eliminate 
the root cause of the unsafe condition. The commenter further suggested 
that relying on pilot response to address a catastrophic hazard is not 
always valid. The commenter stated that a design solution is available 
that would eliminate the uncontrollable high thrust condition. The 
commenter asserted that the FAA's proposed AD contradicts its guidance 
in draft advisory circular (AC) AC 25.901-2X. The acceptable design 
solution suggested by the commenter is a similar installation on 
another aircraft identified in the NTSB investigation report (NTSB/AAR-
10/02) and addressed through AD 2016-13-13, Amendment 18577 (81 FR 
44494, July 8, 2016) (``AD 2016-13-13''). The commenter noted that AD 
2016-13-13 requires installation of a control system modification that, 
following a single failure cause, prevents uncontrolled high failure 
thrust from occurring and prevents the engine from accelerating above 
idle. The commenter further stated that Draft AC 25.901-2X identified 
that assuming a crew response to address a hazard is not proper.
    The FAA infers that the commenter is requesting corrective action 
that does not rely on crew action, similar to the modification required 
by AD 2016-13-13. The FAA acknowledges that Draft AC 25.901-2X suggests 
that relying on pilot response to address a catastrophic hazard is not 
always feasible; however, Draft AC 25.901-2X is not current agency 
guidance because it has not yet been finalized and issued. In addition, 
the FAA has determined that in some cases, including this one, relying 
on pilot response to address a hazard is

[[Page 30839]]

appropriate. The installation of a T/R VCWS and performance of a 
functional test, as required by paragraph (g) of this AD, adequately 
addresses the unsafe condition on the affected airplanes. The T/R VCWS 
monitors the thrust reversers and provides voice command when needed, 
which will enable a faster pilot response to decelerate the airplane. 
However, if the FAA obtains and analyzes additional data that indicates 
the unsafe condition has not been adequately addressed by this AD, the 
FAA will consider further rulemaking. The FAA has not changed this AD 
in this regard.

Request To Shorten the Compliance Time

    The NTSB requested that the FAA shorten the proposed compliance 
time of 1,200 hours time-in-service or 48 months, because of how much 
time has passed since the NTSB's July 17, 2009, safety recommendation 
regarding this issue.
    The FAA disagrees with the commenter's request. Based on the FAA's 
risk assessment, the FAA has determined that the proposed compliance 
time in this AD is adequate to address the unsafe condition. In 
developing an appropriate compliance time for this action, the agency 
considered the urgency associated with the unsafe condition and the 
practical aspects of accomplishing the required modification within a 
period of time that corresponds to the normal scheduled maintenance for 
most affected owners/operators. The FAA has not changed this AD in this 
regard.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule as proposed except for minor editorial 
changes. The FAA has determined that these minor changes:
    <bullet> Are consistent with what was proposed in the NPRM for 
addressing the unsafe condition; and
    <bullet> Do not add any burden upon the public than was proposed in 
the NPRM.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Bombardier Learjet 60 Service Bulletin SB 60-78-9, 
dated June 25, 2018. This service information contains procedures for 
installing a T/R VCWS to alert the pilot of a T/R malfunction. 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 section.

Costs of Compliance

    The FAA estimates that this AD affects 289 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
----------------------------------------------------------------------------------------------------------------
Install a T/R VCWS....................  20 work-hours x $85 per          $28,274         $29,974      $8,662,486
                                         hour = $1,700.
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some of the costs of this AD may be 
covered under warranty, thereby reducing the cost impact on affected 
individuals. The FAA does not control warranty coverage for affected 
individuals. As a result, the FAA has included all costs in this cost 
estimate.

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, 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.

Adoption of 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 (AD):

2020-11-04 Learjet Inc.: Amendment 39-21129; Docket No. FAA-2019-
0204; Project Identifier 2018-CE-042-AD.

(a) Effective Date

    This AD is effective June 25, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Learjet Inc. Model 60 airplanes, serial 
numbers 60-001 through 60-430 inclusive, certificated in any 
category.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 78, Engine Exhaust.

(e) Unsafe Condition

    This AD was prompted by a report of a reverse thrust command 
accelerating the airplane instead of decelerating the airplane 
because the thrust reverser doors were stowed instead of deployed. 
The FAA is

[[Page 30840]]

issuing this AD to mitigate failure of the engine thrust reverser 
system. The unsafe condition, if not addressed, could result in the 
airplane overrunning the runway or a runway excursion.

(f) Compliance

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

(g) Install a Thrust Reverser Voice Command Warning System

    Within the next 1,200 hours time-in-service or within the next 
48 months after June 25, 2020 (the effective date of this AD), 
whichever occurs first, install a Thrust Reverser Voice Command 
Warning System and perform a functional test in accordance with 
sections 3.A. through 3.C. of the Accomplishment Instructions in 
Bombardier Learjet 60 Service Bulletin SB 60-78-9, dated June 25, 
2018.

(h) 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 (i) 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.

(i) Related Information

    For more information about this AD, contact James Galstad, 
Aerospace Engineer, Wichita ACO Branch, 1801 Airport Road, Room 100, 
Wichita, Kansas 67209; telephone: (316) 946-4135; fax: (316) 946-
4107; email: [email protected] or [email protected].

(j) 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 this AD specifies otherwise.
    (i) Bombardier Learjet 60 Service Bulletin SB 60-78-9, dated 
June 25, 2018.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact 
Learjet Inc., MS 53, P.O. Box 7707, Wichita, Kansas 67277-7707; 
telephone: (toll free) 1-866-538-1247; (514) 855-2999; internet: 
https://my.businessaircraft.bombardier.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 901 
Locust, Kansas City, Missouri 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 May 15, 2020.
Lance T. Gant,
 Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-10915 Filed 5-20-20; 8:45 am]
 BILLING CODE 4910-13-P

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