DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1059; Project Identifier 2017-CE-035-AD; Amendment
39-21335; AD 2020-24-05]
RIN 2120-AA64

Airworthiness Directives; Piper Aircraft, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Piper Aircraft, Inc. (Piper) Models PA-28-140, PA-28-150, PA-
28-160, PA-28-180, PA-28-235, PA-32-260, and PA-32-300 airplanes. This
AD was prompted by reports of corrosion found in an area of the main
wing spar not easily accessible for inspection. This AD requires
inspecting the left and right main wing spars for corrosion, and, if
corrosion is found, taking all necessary corrective actions. 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 a certain publication listed in this AD as of December 28,
2020.

ADDRESSES: For service information identified in this final rule,
contact Piper Aircraft, Inc., 2926 Piper Drive, Vero Beach, Florida
32960; telephone: (772) 567-4361; internet: https://www.piper.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 on the internet at https://www.
regulations.gov by searching for and locating Docket No. FAA-2017-1059.

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2017-1059;
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, 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: Dan McCully, Aerospace Engineer, FAA,
Atlanta ACO Branch, 1701 Columbia Avenue, College Park, Georgia 30337;
telephone: (404) 474-5548; fax: (404) 474-5606; email:
william.mccully@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a supplemental notice of proposed rulemaking (SNPRM)
to amend 14 CFR part 39 by adding an AD that would apply to certain
serial-numbered Piper Models PA-28-140, PA-28-150, PA-28-160, PA-28-180, PA-
28-235, PA-32-260, and PA-32-300 airplanes. The SNPRM published in the
Federal Register on August 4, 2020 (85 FR 47118). The FAA preceded the
SNPRM with a notice of proposed rulemaking (NPRM) that published in the
Federal Register on November 7, 2017 (82 FR 51583).
The NPRM proposed to require installing inspection access panels in
the lower wing skin near the left and the right main wing spars (if not
already there), inspecting for corrosion, and taking all necessary
corrective actions if corrosion is found. The NPRM was prompted by
reports of significant corrosion found in an area of the main wing spar
not easily accessible for inspection.
After the NPRM was issued, Piper revised its service information to
add a minimum thickness dimension for the top inboard wing skin and to
include procedures for reapplying corrosion preventive compound if
removed during the inspection. Also, at the request of some commenters,
the FAA replaced the proposal in the NPRM to install access panels for
the visual inspection with optional access methods: The use of existing
access panels, installation of access panels, accessing the area during
a concurrent inspection, or using a borescope through existing holes or
openings. In the SNPRM, the FAA proposed to inspect the left and right
main wing spar for corrosion, and, if corrosion is found, take all
necessary corrective actions.
Corrosion of the main wing spar, if not detected and corrected,
could cause the main wing spar to fail with consequent loss of control
of the airplane. The FAA is issuing this AD to address the unsafe
condition on these products.

Comments

The FAA received a comment from an individual commenter. The
commenter supported the SNPRM without change.

Changes to the SNPRM

The FAA has removed the proposed requirement in paragraph (g) of
the SNPRM to clean the inspection area in accordance with the
instructions in the service information. Operators who access the
inspection area by a method other than the inspection panels may not
have sufficient access to clean the area as described in the service
information. The FAA has added language to paragraph (h)(1) of the
SNPRM to clarify that if corrosion exceeds the minimum allowable limit,
the structure must be repaired using a method approved by the FAA
office specified in this AD.

Conclusion

The FAA reviewed the relevant data, considered the comment
received, and determined that air safety requires adopting the AD as
proposed with the clarification previously described. 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 Piper Service Bulletin No. 1304A, dated August 14,
2018 (Piper SB 1304A). The service bulletin contains procedures for
installing an inspection access panel in the lower wing skin near the
left and the right main wing spars, if not already there, inspecting
for corrosion, and, if corrosion is found, taking all necessary
corrective actions. The service bulletin also contains procedures for
applying corrosion prevention and for verifying that the top inboard
wing skin thickness meets or exceeds the minimum thickness after
corrosion is removed. 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.

Differences Between This AD and the Service Information

Piper SB No. 1304A provides the manufacturer's procedures for
installing access panels on the lower skin of the left wing and the
right wing for easier access to the left and right main wing spar. This
AD does not require installing the access panels, but instead allows
the installation as an option to access the inspection area.
In addition, Piper SB 1304A contains actions labeled ``Required for
Compliance'' (RC), and the language in the service bulletin and in
paragraph (j)(3) of this AD indicates that operators must comply with
all actions labeled RC for compliance with this AD. However, this AD
does not require all of the steps labeled as RC. Operators only need to
comply with the RC steps called out in paragraphs (g) and (h) of this
AD.

Costs of Compliance

The FAA estimates that this AD affects 11,476 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

Optional Costs

This AD does not require the installation of the access panels for
the visual inspection; however, it allows the installation of the
panels, as one of four options, to access the inspection area.

On-Condition Costs

The extent of damage found during the required inspection could
vary significantly from airplane to airplane. The FAA has no way of
determining how much damage may be found on each airplane, the cost to
repair damaged parts on each airplane, or the number of airplanes that
may require repair.

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 that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska to the extent
that it justifies making a regulatory distinction, 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 adding the following new airworthiness
directive: