DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0991; Project Identifier AD-2020-00478-Q]
RIN 2120-AA64

Airworthiness Directives; Garmin International GMN-00962 GTS
Processor Units (GTS 825, GTS 855, GTS 8000)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Garmin International (Garmin) GMN-00962 GTS processor units
(GTS 825, GTS 855, GTS 8000). This proposed AD was prompted by reports
of GTS processor units issuing resolution advisories (RAs) when no risk
of collision or loss of separation exists between the airplanes
involved. This proposed AD would require updating the software version
of the affected GTS Processor units. The FAA is proposing this AD to
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by January 28,
2021.

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 https://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 Garmin
International, Garmin Aviation Support, 1200 E 151st Street, Olathe, KS
66062; phone: (866) 739-5687; website: https://fly.garmin.com/fly-garmin/
support/. You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 901 Locust
St., 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-2020-0991; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Paul Rau, Aviation Safety Engineer,
Wichita ACO Branch, FAA, 1801 Airport Road, Wichita, KS 67209; phone:
(316) 946-4149; fax: (316) 946-4107; email: paul.rau@faa.gov or
Wichita-COS@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites 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-2020-0991;
Project Identifier AD-2020-00478-Q" at the beginning of your comments.
The most helpful comments reference a specific portion of the proposal,
explain the reason for any recommended change, and include supporting
data. The FAA will consider all comments received by the closing date
and may amend this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Paul
Rau, Aviation Safety Engineer, Wichita ACO Branch, FAA, 1801 Airport
Road, Wichita, KS 67209. Any commentary that the FAA receives which is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.

Background

In 2017, the FAA received seven reports of false RAs involving
aircraft equipped with Garmin GMN-00962 GTS processor configured for
traffic collision avoidance system II (TCAS II) (configuration marketed
as GTS-8000 units). The Garmin GMN-00962 GTS processor units are
marketed by Garmin as the GTS 825, GTS 855 or GTS 8000, with the
marketing name representing the traffic system configuration.

A false RA occurs when there is no risk of collision or loss of
separation of the airplanes. The FAA review of available air traffic
data identified additional false RA incidents occurring at rates as
frequent as once every 420 flight hours in congested airspace. These
false RAs result from the GTS Processor software potentially
calculating incorrect range rates. This results in traffic advisories
or RAs being generated when targets are greater than 10 nautical miles
(NM) away. A TCAS event involving three or more airplanes can result in
mid-air collision by increasing the risk that the TCAS, in resolving
the false RA with the initial airplane, will create an actual loss of
separation with a third airplane.

This condition, if not addressed, could result in an RA being
generated when no risk of loss of separation or risk of collision
exists between the airplanes involved, which can lead to a mid-air
collision with a third airplane.

The affected GTS processor units were installed on the airplanes
listed below during production; however, the affected units may have
been installed on other airplane models as a supplemental type
certificate. Although the names found in parenthesis may not be listed
on the type certificate, the manufacturer may use those names as
marketing names for the airplanes.

Textron Aviation Inc. (type certificate previously held by
Cessna Aircraft Company) Model 525 (Cessna Citation M2), Model 525B
(Cessna Citation CJ3+), Model Model 680 Sovereign, Model 680A Latitude,
and Model 700 (Cessna Citation Longitude);

Embraer S.A. Model EMB-500 (Phenom 100) and Model EMB-505
(Phenom 300); and

Learjet Inc. Model 45 (Learjet 70) and Model 45 (Learjet 75).

FAA's Determination

The FAA is issuing this NPRM after determining the unsafe condition
described previously is likely to exist or develop in other products of
these same type design.

Related Service Information

The FAA reviewed Garmin Service Bulletin No. 2065, Revision A,
dated May 7, 2020; and Garmin Service Bulletin No. 1948, Revision B,
dated March 26, 2020. These service bulletins contain procedures for
uploading the software update to the GMN-00962 GTS Processor units (GTS
825, GTS 855, GTS 8000).

Proposed AD Requirements in This NPRM

This proposed AD would require updating the GTS processor unit
software within 12 months.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 700 appliances installed on airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs

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

The FAA has 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) Would not affect intrastate aviation in Alaska, and

(3) Would 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: