DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0470; Project Identifier AD-2023-00694-A]
RIN 2120-AA64

Airworthiness Directives; Textron Aviation Inc. (Type Certificate
Previously Held by Cessna Aircraft Company) Airplanes

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 Textron Aviation Inc. (Textron) (type certificate previously held
by Cessna Aircraft Company) Model 525, 525A, and 525B airplanes with
Tamarack active technology load alleviation system (ATLAS) winglets
installed per Supplemental Type Certificate (STC) No. SA03842NY. This
proposed AD was prompted by a report of an un-annunciated failure of
the ATLAS system. This proposed AD would require installing placards on
the left-hand inboard edge of the Tamarack active camber surface (TACS)
and revising the existing airplane flight manual (AFM) for your
airplane. 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 May 6,
2024.

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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-0470; 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.
Material Incorporated by Reference:
For material identified in this NPRM, contact Tamarack
Aerospace Group, Inc., 2021 Industrial Drive, Sandpoint, ID 83864;
phone: (208) 597-4568; website: tamarackaero.com/customer-support.
You may view this material 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 (817) 222-5110.

FOR FURTHER INFORMATION CONTACT: Anthony Caldejon, Aviation Safety
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone:
(206) 231-3534; email: anthony.v.caldejon@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 ADDRESSES. Include ``Docket No. FAA-2024-0470; Project Identifier
AD-2023-00694-A'' 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
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
Anthony Caldejon, Aviation Safety Engineer, FAA, 3960 Paramount
Boulevard, Lakewood, CA 90712. Any commentary that the FAA receives
which is not specifically designated as CBI will be placed in the
public docket for this rulemaking.

Background

The FAA received a report that, while accomplishing a reliability
improvement program, Tamarack discovered the potential for a failure of
the ATLAS system in which a loss of load alleviation would be un-
annunciated. The manufacturer's investigation revealed that failure of
either of one of a pair of opto-isolators within the ATLAS Control Unit
(ACU) can prevent an enable signal from being sent to the TACS Control
Units (TCUs).
The ATLAS system is installed on Textron Model 525, 525A, and 525B
airplanes under STC No. SA03842NY and lessens the increased wing loads
associated with the installation of winglets. The ATLAS is designed to
detect flight conditions and modify airflow at the wing tip
accordingly. The ATLAS will draw power constantly to operate the logic
circuit and provide power to the actuators to maintain TACS position.
The TCUs include the linear electric actuators and motor
controllers that move the TACS. Since the enable signals are not
monitored after the opto-isolators, the ACU cannot detect whether the
generated signal is reaching the TCUs. The TCUs rely on the enable
signal to determine whether to respond
to commands from the ACU. If one of the opto-isolators fails, the ACU
would not be able to detect that the TCUs were not enabled and the TCUs
would not respond to commands from the ACU. Thus, the system would be
operating in a mode of un-annunciated loss of load alleviation. The
flight crew would be unaware of a malfunction of the load alleviation
function of ATLAS and could fly the airplane into conditions that
exceed the limit load. In addition, fatigue concerns could result in
cracking of the airplane's primary structure. If not addressed, this
condition could result in loss of continued safe flight and landing of
the airplane.

FAA's Determination

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

Related Service Information Under 1 CFR Part 51

The FAA reviewed Tamarack Aerospace Service Bulletin SBATLAS-57-06,
Issue A, dated April 19, 2023. This service information specifies
procedures for installing placards on the left-hand inboard edge of the
TACS to enhance visibility of TACS movement during night operations.
The FAA also reviewed the following AFM supplements, which contain,
among other items, instructions for pre-flight checks of the ATLAS
system before taxi. These documents are distinct because they apply to
different airplane models.
Tamarack Aerospace Cessna Citation Model 525, 525-0001
thru -0359, AFM Supplement TAG-1101-0099 CA/DD/M023, Tamarack Active
Technology Load Alleviation System (Atlas) Winglets, Issue D, dated
September 20, 2023.
Tamarack Aerospace Cessna Citation Model 525, 525-0360
through -0599, AFM Supplement TAG-1101-1099 CA/DD/M037, Tamarack Active
Technology Load Alleviation System (Atlas) Winglets, Issue D, dated
September 20, 2023.
Tamarack Aerospace Cessna Citation Model 525, 525-0600
through -0684 and -0686 through -0701, AFM Supplement TAG-1101-1099 CA/
DD/M038, Tamarack Active Technology Load Alleviation System (Atlas)
Winglets, Issue D, dated September 20, 2023.
Tamarack Aerospace Cessna Citation Model 525, 525-0685 and
-0800 and on, AFM Supplement TAG-1101-M099 CA/DD/M088, Tamarack Active
Technology Load Alleviation System (Atlas) Winglets, Issue D, September
20, 2023.
Tamarack Aerospace Cessna Citation Model 525A, 525A-0001
thru -0299, AFM Supplement TAG-1102-0099 CAS/AFM0003, Tamarack Active
Technology Load Alleviation System (Atlas) Winglets, Issue C, September
20, 2023.
Tamarack Aerospace Cessna Citation Model 525A, 525A-0300
and on, AFM Supplement TAG-1102-P099 CAS/AFM0004, Tamarack Active
Technology Load Alleviation System (Atlas) Winglets, Issue C, September
20, 2023.
Tamarack Aerospace Cessna CitationJet Model 525B, 525B-
0001 thru 525B-0056 and 525B-0058 thru 525B-0450, AFM Supplement TAG-
1103-0099 CAS/AFM0001, Tamarack Active Technology Load Alleviation
System (Atlas) Winglets, Issue C, September 20, 2023.
Tamarack Aerospace Cessna CitationJet Model 525B, 525B-
0057 and 525B-0451 and on, AFM Supplement TAG-1103-P099 CAS/AFM0002,
Tamarack Active Technology Load Alleviation System (Atlas) Winglets,
Issue D, September 20, 2023.
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.

Proposed AD Requirements in This NPRM

This proposed AD would require installing placards on the left-hand
inboard edge of the TACS and revising the existing AFM for your
airplane. Revising the AFM for your airplane by updating the Normal
Procedures section may be performed by the owner/operator (pilot)
holding at least a private pilot certificate may revise the AFM for
your airplane and must enter compliance with the applicable paragraph
of this proposed AD into the airplane maintenance records in accordance
with 14 CFR 43.9(a) and 91.417(a)(2)(v). The pilot may perform this
action because it only involves revising the flight manual. This action
could be performed equally well by a pilot or mechanic. This is an
exception to the FAA's standard maintenance regulations.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 148 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 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: