DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0204; Product Identifier 2018-CE-042-AD]
RIN 2120-AA64

Airworthiness Directives; Learjet Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Learjet Inc. Model 60 airplanes. This proposed 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 proposed AD
would require installing a Thrust Reverser (T/R) Voice Command Warning
System (VCWS) to alert the crew of a T/R malfunction. We are proposing
this AD to address the unsafe condition on these products.

DATES: We must receive comments on this proposed AD by June 27, 2019.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, 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, Policy and Innovation Division, 901 Locust,
Kansas City, Missouri 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 on the internet at http://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 NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (phone: 800-647-
5527) is listed above. Comments will be available in the AD docket
shortly after receipt.

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:
james.galstad@faa.gov or Wichita-COS@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2019-0204;
Product Identifier 2018-CE-042-AD" at the beginning of your comments.
We specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this NPRM. We will consider all
comments received by the closing date and may amend this NPRM because
of those comments.

We will post all comments we receive, without change, to http://www.
regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this NPRM.

Discussion

We received 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.

We consider this NPRM to be the third of three ADs that are related
to each other, and 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. This proposed AD would
require installing a T/R VCWS to alert the crew of a T/R malfunction.
We are proposing this AD to mitigate failure of the engine thrust
reverser system.

This condition, if not addressed, could result in the airplane
overrunning the runway or a runway excursion.

Related Service Information Under 1 CFR Part 51

We reviewed Bombardier Learjet 60 Service Bulletin SB 60-78-9,
dated June 25, 2018. The service bulletin 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.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would require installing the T/R VCWS.

Costs of Compliance

We estimate that this proposed AD affects 289 airplanes of U.S.
registry.

We estimate the following costs to comply with this proposed AD:

Estimated costs

According to the manufacturer, some of the costs of this proposed
AD may be covered under warranty, thereby reducing the cost impact on
affected individuals. We do not control warranty coverage for affected
individuals. As a result, we have included all costs in our 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.

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.

This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to small airplanes, gliders,
balloons, airships, domestic business jet transport airplanes, and
associated appliances to the Director of the Policy and Innovation
Division.

Regulatory Findings

We 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 this 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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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 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:

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

Sec. 39.13 [Amended]

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