DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0813; Product Identifier 2019-CE-040-AD; Amendment
39-21387; AD 2021-02-04]
RIN 2120-AA64

Airworthiness Directives; Pilatus Aircraft Ltd. 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
Pilatus Aircraft Ltd. (Pilatus) Model PC-12/47E airplanes. This AD 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 inboard flap fairings aft (IFFAs) having an incorrect shape,
which may result in chafing between the IFFA and the associated front inboard
tension rod. This AD requires an inspection of the IFFAs for the
correct shape and chafing between the IFFA and the associated front
inboard tension rod, with corrective action as necessary. This
condition could lead to failure of the inboard flap drive arm with
consequent asymmetric flap extension, resulting in reduced control of
the airplane. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective March 30, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of March 30,
2021.

ADDRESSES: For service information identified in this final rule,
contact Pilatus Aircraft, Ltd., Customer Support PC-12, CH-6371 Stans,
Switzerland; phone: +41 41 619 33 33; fax: +41 41 619 73 11; email:
supportPC12@pilatus-aircraft.com; website: https://www.pilatus-
aircraft.com. You may review this referenced 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-2020-0813.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0813; 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: Doug Rudolph, Aviation Safety
Engineer, General Aviation & Rotorcraft Section, International
Validation Branch, FAA, 901 Locust, Room 301, Kansas City, Missouri
64106; phone: (816) 329-4059; fax: (816) 329-4090; email:
doug.rudolph@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all Pilatus Model PC-
12/47E airplanes. The NPRM published in the Federal Register on
September 16, 2020 (85 FR 57804). In the NPRM, the FAA proposed to
require an inspection of the IFFAs for the correct shape and chafing
between the IFFA and the associated front inboard tension rod, with
corrective action as necessary.
The NPRM was based on MCAI from the European Union Aviation Safety
Agency (EASA), which is the Technical Agent for the Member States of
the European Union. EASA issued AD No.: 2019-0231, dated September 13,
2019 (referred to after this as ``the MCAI''), to correct an unsafe
condition for Pilatus Model PC-12/47E airplanes. The MCAI states:

On the final assembly line of PC-12/47E aeroplanes, IFFAs were
detected having an incorrect shape. As a consequence, chafing
between the IFFA and the associated front inboard tension rod could
occur, may cause corrosion of the bare rod aluminium tube and reduce
aluminium thickness.
This condition, if not detected and corrected, could lead to
failure of the inboard flap drive arm with consequent asymmetric
flap extension, possibly resulting in reduced control of the
aeroplane.
To address this potential unsafe condition, Pilatus issued the
[service bulletin] SB to provide inspection and modification
instructions.
For the reason described above, this [EASA] AD requires a one-
time inspection of both IFFA and, depending on findings, a follow-on
inspection of the associated front inboard tension rod for chafing,
and modification or replacement of affected parts.

You may examine the MCAI at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0813.

Discussion of Final Airworthiness Directive

Comments

The FAA received two comments from Pilatus. The following presents
the comments received on the NPRM and the FAA's response to each
comment.
Pilatus requested the FAA reduce the applicability of the proposed
AD from all Model PC-12/47E airplanes to Model PC-12/47E airplanes with
serial number (S/N) 1576 and higher. Pilatus stated that due to an
engineering change in 2014, the left-hand (LH) IFFA, part number (P/N)
557.52.12.223, and the right-hand (RH) IFFA, P/N 557.52.12.224,
introduced on airplanes with S/N 1576 and higher, have different
attachment hole positions and a maximum hole position difference of
more than 12mm. As a result, it is not physically possible to install
P/Ns 557.52.12.223 and 557.52.12.224 on airplanes with an S/N lower
than 1576.
The FAA partially agrees. The commenter is correct that the
affected IFFAs cannot be installed on Model PC-12/47E airplanes with an
S/N lower than 1576. The FAA has revised paragraph (f) of this AD to
limit the inspection of the IFFAs to airplanes with an S/N 1576 and
higher.
Pilatus acknowledged that tension rod P/N 527.52.12.135 can be
installed on all Model PC-12/47E airplanes but requested the FAA limit
the tension rod inspection for airplanes with an S/N lower than 1576 to
only those with maintenance records showing that the tension rod had
been installed.
The FAA partially agrees. The FAA has revised the tension rod
inspection to limit its scope for airplanes with an S/N lower than
1576. Because the tension rods are not life-limited parts, there is no
regulatory requirement for them to be serialized or for operators to
record or retain information about the part's traceability. Therefore,
operators would be unable to comply with, and the FAA would be unable
to enforce, the change requested by the commenter, as maintenance
records may not identify if a tension rod was removed from an airplane
with an S/N 1576 or higher. Instead, the FAA has changed the AD so that
the inspection of the tension rod is required for all airplanes with a
S/N 1576 or higher and for airplanes with a S/N 1001 through 1575 if
tension rod P/N 527.52.12.135 is installed.

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for the changes described
previously, this AD is adopted as proposed in the NPRM. None of the
changes will increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Pilatus PC-12 Service Bulletin No: 27-026, dated
July 10, 2019 (Pilatus SB No. 27-026). The service information
specifies procedures for inspecting and correcting chafing between the
left and right IFFAs and the associated front inboard tension rods.
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.

Differences Between This AD and the MCAI

The MCAI only requires inspection of the tension rods if the IFFAs
are modified because they have been found to have the incorrect shape.
Due to the length of time between manufacture and the issuance of this
AD, operators could have installed an affected tension rod onto an
airplane that was not manufactured with the defective part. Therefore,
this AD requires inspection for chafing damage on the tension rods on
all Model PC-12/47E airplanes that have an affected tension rod
installed.

Costs of Compliance

The FAA estimates that this AD will affect 18 products of U.S.
registry. The FAA also estimates that it will take about 2.5 work-hours
per product to comply with the requirements of this AD. The average
labor rate is $85 per work-hour. Required parts will cost about $1,600
per product.
Based on these figures, the FAA estimates the cost of this AD on
U.S. operators will be $32,634 or $1,813 per product.
The FAA has included all costs in this cost estimate. According to
the manufacturer, however, all or 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 that 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 adding the following new airworthiness
directive: