DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1078; Project Identifier AD-2020-00716-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 all Textron Aviation Inc. (Textron) (Type Certificate previously
held by Cessna Aircraft Company) Models 210N, 210R, P210N, P210R,
T210N, T210R, 177, 177A, 177B, 177RG, and F177RG airplanes. This
proposed AD was prompted by the in-flight break-up of a Model T210M
airplane in Australia, due to fatigue cracking that initiated at a
corrosion pit, and subsequent corrosion reports on other Model 210-
series and Model 177-series airplanes. This proposed AD would require
visual and eddy current inspections of the carry-thru spar lower cap,
corrective action if necessary, application of a protective coating and
corrosion inhibiting compound (CIC), and reporting the inspection
results to the FAA. 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 June 25,
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 Textron
Aviation Inc., One Cessna Boulevard, Wichita, KS 67215; phone: (316)
517-6061; email: structures@txtav.com; website: https://support.cessna.
com. You may view this referenced service information 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 (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-2020-1078; 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: Bobbie Kroetch, Aviation Safety
Engineer, Wichita ACO Branch, FAA, 1801 Airport Rd, Wichita, KS 67209;
phone: (316) 946-4155; fax: (316) 946-4107; email:
bobbie.kroetch@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 ADDRESSES. Include Docket No. FAA-2020-1078; Project Identifier
AD-2020-00716-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
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
Bobbie Kroetch, Aviation Safety Engineer, Wichita ACO Branch, FAA, 1801
Airport Rd, 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

The FAA received a report that, on May 26, 2019, a Textron Model
T210M airplane experienced an in-flight break-up while performing low-
altitude aerial survey operations in Australia. The carry-thru spar
failed and resulted in wing separation and loss of control of the
airplane. A visual examination of the fracture surface identified
fatigue cracking that initiated at a corrosion pit. The FAA issued an
airworthiness concern sheet (ACS) on June 27, 2019, advising owners and
operators of the accident and requesting relevant information about the
fleet.

Following the ACS, the FAA received reports of widespread and
severe corrosion of the carry-thru spar. Earlier Models 210G, T210G,
210H, T210H, 210J, T210J, 210K, T210K, 210L, T210L, 210M, and T210M
airplanes experienced the most widespread and severe corrosion, and the
FAA issued AD 2020-03-16 (85 FR 10043, February 21, 2020) (AD 2020-03-
16) as a final rule; request for comments to immediately address the
unsafe condition on those airplanes.

The FAA also received reports of corrosion on later Models 210N,
P210N, T210N, 210R, P210R, and T210R airplanes and Model 177-series
airplanes. On Models 210N, P210N, T210N, 210R, P210R, and T210R
airplanes, the upper surface of the carry-thru spar is covered by
fuselage skin and is not exposed to the environment. This removes the
leak paths at the skin splices common to the earlier Model 210
airplanes and reduces the potential for moisture intrusion.
Additionally, the later Model 210 airplanes were manufactured with zinc
chromate primer applied to all carry-thru spars. However, the later
Model 210 airplanes were also delivered with foam installed along the
carry-thru spar lower cap. The foam traps moisture against the lower
surface of the carry-thru spar cap, which can aid in the development of
corrosion. The Model 177-series airplanes share a similar carry-thru
spar design with the earlier Model 210-series airplanes: The upper
surface of the carry-thru spars are exposed, and the spars may not have
been delivered with zinc chromate primer applied. Although Model 177-
series airplanes were not delivered with foam padding installed on the
lower surface of the carry-thru spar, corrosion has been reported on
the carry-thru spar lower cap. Corrosion of the carry-thru spar lower
cap can lead to fatigue cracking or reduced structural strength of the
carry-thru spar, which, if not addressed, could result in wing
separation and loss of control 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 the following service documents proposed for
compliance with this NPRM:

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, Revision 2, dated August, 3, 2020 (SEL-57-08R2); and

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-09, Revision 1, dated August, 3, 2020 (SEL-57-09R1).

For the applicable airplanes specified, these service letters
contain instructions for visually inspecting the carry-thru spar for
corrosion, damage, and cracks and for completing an eddy current
inspection. This service information also specifies applying protective
coating and CIC.

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 of this
NPRM.

Other Related Service Information

The FAA reviewed the following service letters related to this
NPRM, which, for the applicable airplanes specified, contain
instructions for visually inspecting the carry-thru spar for corrosion
and doing an eddy current inspection of the carry-thru spar regardless
of whether corrosion was found and removed. This service information
also contains instructions for applying CIC, but does not specify
applying protective coating.

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-06, dated June, 24, 2019 (SEL-57-06);

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-06, Revision 1, dated November 19, 2019;

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-07, dated June 24, 2019 (SEL-57-07); and

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-07, Revision 1, dated November 19, 2019.

The FAA also reviewed the service letters listed below related to
this NPRM, which, for the applicable airplanes specified, contain the
same instructions and repair criteria as SEL-57-08R2 and SEL-57-09R1.

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, dated November 1, 2019;

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, Revision 1, dated November 19, 2019; and

Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-09, dated November 19, 2019.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in SEL-57-08R2 and SEL-57-09R1, except as discussed under Differences
Between this Proposed AD and the Service Information. This proposed AD
also requires reporting the inspection results to the FAA by email at
Wichita-COS@faa.gov.

Differences Between This Proposed AD and the Service Information

Although Textron SEL-57-08R2 also applies to Models 210G,
T210G, 210H, T210H, 210J, T210J, 210K, T210K, 210L, T210L, 210M, and
T210M airplanes, this proposed AD would not. The FAA issued AD 2020-03-
16 to address the immediate safety of flight for those airplanes.

Textron SEL-57-08R2 and Textron SEL-57-09R1 specify
inspecting all interior surfaces of the carry-thru spar; additionally,
Textron SEL-57-09R1 specifies inspecting the lower surface of the
outboard spar to wing attach lugs. This proposed AD would only require
inspecting the carry-thru spar lower cap, including the lower surface,
edge, and upper surface of the lower cap. While the web, upper cap, and
lugs of the carry-thru spar may be susceptible to corrosion, evidence
does not support including inspection of these areas as part of this
proposed AD. The FAA will continue to monitor reports of corrosion on
all areas of the carry-thru spar for potential future action.

Textron SEL-57-08R2 and Textron SEL-57-09R1 do not require
an eddy current inspection on the carry-thru spar unless the amount of
material removed in the blended area exceeds 0.010 inch deep but is
within limits. This proposed AD would require an eddy current
inspection of all locations on the carry-thru spar where corrosion was
removed. The fatigue crack on the Model T210M airplane that suffered
the fatal in-flight break-up initiated from a corrosion pit
approximately 0.011 inch deep in the lower cap kick area. The visual
and less restrictive eddy current inspection requirements specified in
SEL-57-08R2 and SEL-57-09R1 could potentially miss similar fatigue
cracks on airplanes currently operating in the field.

Textron SEL-57-08R2 and Textron SEL-57-09R1 only require
eddy current inspection of the lower cap kick of the carry-thru spar if
corrosion is identified on the carry-thru spar cap. This proposed AD
would require a one-time eddy current inspection of the lower cap kick
area of all affected airplanes, regardless of the results of the visual
inspection. The fatigue crack on the Model T210M airplane that suffered
the fatal in-flight break-up initiated in the lower cap kick area.
Cracks and corrosion damage may be difficult to identify through visual
inspection alone. The FAA will use the results of the one-time eddy
current inspection of the lower cap kick area, in part, to determine
the necessity of future rulemaking action.

Textron SEL-57-08R2 and Textron SEL-57-09R1 specify
contacting Textron for evaluation and disposition of certain damage.
Instead, this proposed AD would require removing the carry-thru spar
from service or repairing it (if possible) in accordance with the AMOC
procedures identified in paragraph (o) of this proposed AD. Operators
should work with Textron to develop a repair in support of an AMOC
request.

Textron SEL-57-08 R2 and Textron SEL-57-09R1 provide
instruction allowing airplanes that have complied with SEL-57-06 or
SEL-57-07 to complete the application of the protective coating and CIC
within 200 flight hours or at the next annual inspection, whichever
occurs first. This proposed AD would permit those airplanes that have
complied with the visual and eddy current inspections in SEL-57-06 or
SEL-57-07, as required by paragraphs (g) and (h) of this proposed AD,
to complete the application of the protective coating and CIC within 24
months from the date of the visual and eddy current inspections or
within 12 months after the effective date of this AD, whichever occurs
first.

Interim Action

The FAA considers this proposed AD an interim action. This proposed
AD would require a one-time visual inspection of specified areas on the
carry-thru spar lower cap and an eddy current inspection of the lower
cap kick area and any locations where corrosion was removed. This
proposed AD would also require reporting the inspection results to the
FAA. The FAA will analyze the inspection results received to determine
further rulemaking action.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 3,421 airplanes of U.S. registry.

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

Estimated Costs

* Model 210-series airplanes may only require application of
corrosion inhibitor, depending on the condition of the zinc chromate
primer. Model 177-series airplanes may or may not require application
of the primer, depending on the production year and the quality of any
existing zinc chromate primer.

The FAA estimates the following costs to do any necessary repairs
or replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
aircraft that might need these actions:

On-Condition Costs

The amount of work-hours necessary to complete the eddy current
inspection and corrosion removal will depend on the extent of the
corrosion on the spar. The FAA has no way of estimating the work-hours
that may be required for those procedures. The FAA's cost estimate
assumes a minimum of one hour for the eddy current inspection and two
hours for the corrosion removal. If the operator needs an alternative
method of compliance for repair, the FAA has no way of estimating the
extent of damage or follow-on eddy current inspection that may be
required. The FAA has no way of estimating the potential cost of those
actions.

Replacement spars are not currently available from Textron. Textron
no longer produces the current spar design, and they are working to
develop a new spar design. The FAA does not have data to determine the
availability of replacement spars from other sources.

Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a current valid OMB Control Number. The OMB
Control Number for this information collection is 2120-0056. Public
reporting for this collection of information is estimated to take
approximately 2 hours per response, including the time for reviewing
instructions, searching existing data sources, gathering and
maintaining the data needed, and completing and reviewing the
collection of information. All responses to this collection of
information are mandatory. Send comments regarding this burden estimate
or any other aspect of this collection of information, including
suggestions for reducing this burden, to Information Collection
Clearance Officer, Federal Aviation Administration, 10101 Hillwood
Parkway, Fort Worth, TX 76177-1524.

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: