DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0493; Project Identifier 2019-CE-046-AD; Amendment
39-21336; AD 2020-24-06]
RIN 2120-AA64

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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) AD 2019-
08-13 for Textron Aviation, Inc., (type certificate previously held by
Cessna Aircraft Company) Models 525, 525A, and 525B airplanes with
Tamarack Aerospace Group (Tamarack) active load alleviation system
(ATLAS) winglets installed in accordance with Supplemental Type
Certificate (STC) SA03842NY. AD 2019-08-13 was prompted by mandatory
continuing airworthiness information (MCAI) originated by an aviation
authority of another country to identify and correct an unsafe
condition on an aviation product. The MCAI describes the unsafe
condition as malfunction of the ATLAS. This AD results from the
identification of corrective actions that, if implemented, allow
operators to reactivate the ATLAS and restore operations to normal
procedures. The FAA is issuing this AD to address the unsafe condition
on these products.

DATES: This AD is effective December 28, 2020.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of December 28,
2020.

ADDRESSES: For Cranfield Aerospace Solutions Limited and Tamarack
Aerospace Group service information identified in this AD, contact
Tamarack Aerospace Group, Inc. 2021 Industrial Drive, Sandpoint, Idaho
83864; telephone: (208) 255-4400; email: support@tamarackaero.com;
internet: https://tamarackaero.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 at https://www.regulations.gov by searching for
and locating Docket No. FAA-2020-0493.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0493; 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, the
MCAI, 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: Steven Dzierzynski, Aerospace
Engineer, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410,
Westbury, New York 11590; telephone: (516) 287-7367; fax: (516) 794-
5531; email: steven.dzierzynski@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2019-08-13, Amendment 39-19634 (84 FR
24007, May 24, 2019) (AD 2019-08-13). AD 2019-08-13 applied to Textron
Aviation, Inc., Models 525, 525A, and 525B airplanes with Tamarack
ATLAS winglets installed in accordance with STC SA03842NY. The NPRM
published in the Federal Register on June 2, 2020 (85 FR 33583).
AD 2019-08-13 prohibited all flight by revising the operating
limitations in the airplane flight manual and fabricating and
installing a placard, until a modification has been incorporated in
accordance with an FAA-approved method. AD 2019-08-13 was based on MCAI
originated by the European Union Aviation Safety Agency (EASA), which
is the Technical Agent for the Member States of the European Union.
EASA issued AD No. 2019-0086-E, dated April 19, 2019, to address an
unsafe condition related to reports of the ATLAS malfunctioning, which
could lead to loss of control of the airplane.
The NPRM was prompted by EASA's revision to the MCAI. EASA issued
AD No. 2019-0086R1, dated August 9, 2019, to require modifications
previously developed by Cranfield Aerospace Solutions Limited
(Cranfield), the holder of STC SA03842NY, to restore the safety of the
ATLAS design and allow operators to reactivate the ATLAS. In the NPRM,
the FAA proposed to require installing the modified Tamarack Active
Camber Surface (TACS) control unit (TCU) and centering strips and
revising the Tamarack maintenance manual supplement to include
instructions for continued airworthiness relating to the centering
strips. The FAA is issuing this AD to address the unsafe condition on
these products.
You may obtain further information by examining the MCAI in the AD
docket on the internet at https://www.regulations.gov by searching for
and locating Docket No. FAA-2019-0493.

Comments

The FAA received comments from two commenters. The commenters were
Tamarack and the General Aviation Manufacturers Association (GAMA). The
following presents the comments received on the NPRM and the FAA's
response to each comment.

Supportive Comments

Tamarack and GAMA supported the NPRM.

Request To Revise the Preamble

Tamarack requested the FAA correct a statement in the preamble of
the NPRM that the April 13, 2019 incident exposed a failure mode of the
ATLAS that was not anticipated during certification. Tamarack commented
this statement in the NPRM implies that only the worst case condition
was tested while other less critical conditions were not. The commenter
further stated that the failure mode that occurred on April 13, 2019
was tested during certification and shown to be recoverable. The
commenter discussed the investigations and flights tests conducted by
EASA and stated this data was reviewed and validated by the FAA before
the FAA issued AD 2019-08-13.
The FAA partially agrees. The FAA issued AD 2019-08-13 on May 20,
2019. The FAA had received flight path data for the UK incident
aircraft; however, this data did not provide any information about the
operation of the ATLAS system during the incident. Therefore, it was
not considered in the development of the FAA AD. No other information
about the operation of the ATLAS system during this incident has been
provided to the FAA.
The FAA received the root cause report mentioned by the commenter
on April 22, 2019, which deemed further investigation was warranted to
determine if the actions specified in Cranfield's service bulletin
mitigated the unsafe condition. Many discussions between the FAA and
EASA occurred before and after the issuance of AD 2019-08-13. Given
that the Cranfield service bulletin did not contain adequate
instructions for the use of ``speed tape'' to prevent the TACS from
floating, the FAA found it unacceptable for correcting the unsafe
condition. Instead of delaying action to address the unsafe condition
to wait for testing of the ``speed tape,'' the FAA issued AD 2019-08-13
to ground the affected airplanes, knowing that operators could request
an alternative method of compliance when substantiating data became
available or when the investigation was complete.
The FAA did not make changes to this AD based on this comment.

Request To Update the STC Holder

Tamarack requested the FAA update the STC holder and contact
information from Cranfield to Tamarack. The commenter noted that
Cranfield finalized the transfer of STC SA03842NY to Tamarack after the
issuance of AD 2019-08-13.
The FAA agrees and has updated the references as requested.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety requires adopting the AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following service documents required for
compliance with this AD:
Cranfield Aerospace Solutions Limited Service Bulletin
CAS/SB1480, Issue A, dated July 2019, which contains instructions to
ensure installation of a modified TCU and the TACS centering strips;
and
Tamarack Aerospace Group Cessna 525, 525A, & 525B ATLAS
Winglet Maintenance Manual Supplement, Report Number: TAG-1100-0101,
Issue G, dated September 3, 2019, which adds instructions to inspect
the centering strips and adds repetitive inspection intervals to the
Airworthiness Limitations section of the supplement for the centering
strips.
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.

Other Related Service Information

The FAA also reviewed the following documents related to this AD:
Cranfield Aerospace Solutions Limited Service Bulletin
CAS/SB1475, Issue A, dated February 2019, which contains the
instructions for installing the centering strips to the TACS,
identified as modification CAeM/Cessna/1475;
Tamarack Aerospace Group ATLAS Service Bulletin SBATLAS-
57-03, dated July 27, 2018, which contains instructions to remove the
ATLAS TCU and return it to the ATLAS repair facility for modification;
Tamarack Aerospace Group ATLAS Service Bulletin SBATLAS-
57-05, dated February 20, 2019, which contains instructions to install
centering strips on the TACS; and
Cranfield Aerospace Solutions Limited Service Bulletin
CAS/SB1467, Issue B, dated July 2018, which contains instructions to
remove the ATLAS TCU assembly and modify it as specified in CAS/SB1480,
Issue A.

Costs of Compliance

The FAA estimates that this AD will affect 76 products of U.S.
registry. The FAA also estimates that it will take 16 work-hours with a
parts cost of $4,314 per product to modify the TCU, 24 work-hours with
a parts cost of $199 per product to install the centering strips, and 1
work-hour per product to revise the limitations section as required by
this AD. The average labor rate is $85 per work-hour.
Based on these figures, the FAA estimates the cost of this AD on
U.S. operators to be $607,848, or $7,998 per product.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this AD
may be covered under warranty, thereby reducing the cost impact on
affected operators.

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 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

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:

a. Removing Airworthiness Directive 2019-08-13, Amendment 39-19634 (84
FR 24007, May 24, 2019); and

b. Adding the following new airworthiness directive: