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Federal Register / Vol. 86, No. 34 / Tuesday, February 23, 2021 / Rules and Regulations 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.
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.

DATES:

For service information identified in this final rule, contact Pilatus Aircraft, Ltd., Customer Support PC12, CH6371 Stans, Switzerland;
phone: +41 41 619 33 33; fax: +41 41
619 73 11; email: supportPC12@pilatusaircraft.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 3294148. It is also available at https www.regulations.gov by searching for and locating Docket No.
FAA20200813.

ADDRESSES:

Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20200813; 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, M30, West Building Ground Floor, Room W12140, 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 3294059; fax: 816 3294090;
email: doug.rudolph@faa.gov.
SUPPLEMENTARY INFORMATION:

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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 PC12/47E
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.:
20190231, dated September 13, 2019
referred to after this as the MCAI, to correct an unsafe condition for Pilatus Model PC12/47E airplanes. The MCAI
states:
On the final assembly line of PC12/47E
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.
FAA20200813.
Discussion of Final Airworthiness Directive Comments The FAA received two comments from Pilatus. The following presents the comments received on the NPRM and the FAAs response to each comment.
Pilatus requested the FAA reduce the applicability of the proposed AD from all Model PC12/47E airplanes to Model PC12/47E 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
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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 PC12/47E 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 parts 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 PC12
Service Bulletin No: 27026, dated July 10, 2019 Pilatus SB No. 27026. 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
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