DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1074; Project Identifier MCAI-2020-01257-A]
RIN 2120-AA64

Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Pilatus Aircraft Ltd. (Pilatus) Model PC-24 airplanes. This
proposed AD results from 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 identifies the unsafe condition as the engine attachment hardware
not conforming to the approved design, which could affect the
structural integrity of the airplane. This proposed AD would require
inspecting the engine attachment hardware for missing washers and loose
nuts and taking corrective actions as necessary. 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 May 10,
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 Pilatus
Aircraft Ltd., CH-6371, Stans, Switzerland; phone: +41 848 24 7 365;
email: techsupport.ch@pilatus-aircraft.com; website: https://www.pilatus-
aircraft.com/. You may view this 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. It is also available at
https://www.regulations.gov by searching for and locating Docket No.
FAA-2020-1074.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-1074; 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: Doug Rudolph, Aviation Safety
Engineer, FAA, General Aviation & Rotorcraft Section, International
Validation Branch, 901 Locust, Room 301, Kansas City, MO 64106; phone:
(816) 329-4059; fax: (816) 329-4090; email: doug.rudolph@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-2020-1074; Project Identifier
MCAI-2020-01257-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 Doug
Rudolph, Aviation Safety Engineer, FAA, General Aviation & Rotorcraft
Section, International Validation Branch, 901 Locust, Room 301, Kansas
City, MO 64106. 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 European Union Aviation Safety Agency (EASA), which is the
Technical Agent for the Member States of the European Union, has issued
EASA AD 2020-0194, dated September 8, 2020 (referred to after this as
"the MCAI"), to address an unsafe condition on certain serial-
numbered Pilatus Model PC-24 airplanes. The MCAI states:

During a scheduled maintenance inspection, the engine attachment
hardware of a PC-24 airplane was found not to conform to the
approved design. A washer was missing beneath each of the four
mating bolt heads on the rear engine beam. In addition, some of the
keeper fitting attachment bolts on the LH/RH middle inner nacelle
were found with loose nuts. It was also determined that other
aeroplanes may have the same non-conformities.

This condition, if not detected and corrected, could damage the
engine attachment hardware, possibly affecting the structural
integrity of the aeroplane.

To address this potential unsafe condition, Pilatus issued the
[service bulletin] SB, providing instructions for inspection and
corrective action.

For the reason described above, this [EASA] AD requires a one-
time inspection for missing washers and loose nuts on the engine
attachment hardware and, depending on findings, the accomplishment
of applicable corrective action(s).

You may obtain further information by examining the MCAI in the AD
docket at https://www.regulations.gov by searching for and locating
Docket No. FAA-2020-1074.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Pilatus PC-24 Service Bulletin No. 71-001, dated
June 30, 2020. This service information specifies procedures for
inspecting the engine attachment hardware for loose nuts and missing
washers and taking corrective actions depending on findings. 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.

FAA's Determination and Requirements of the Proposed AD

This product has been approved by the aviation authority of another
country and is approved for operation in the United States. Pursuant to
our bilateral agreement with this State of Design Authority, it has
notified the FAA of the unsafe condition described in the MCAI and
service information referenced above. The FAA is issuing this NPRM
after determining the unsafe condition described previously is likely
to exist or develop on other products of the same type design.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 34 airplanes of U.S. registry.

The FAA estimates that it would take 2.5 work-hours to do the one-
time inspections. The average labor rate is $85 per work-hour.

Based on these figures, the FAA estimates the cost of the proposed
AD on U.S. operators would be $7,225 or $212.50 per airplane.

The FAA also estimates that, as on-condition costs, installing
missing washers, replacing bolts, and doing an eddy current inspection
of the bolt holes would take 4.5 work-hours and require parts costing
$200 for a cost of $582.50 per airplane. This estimate assumes
replacing all of the rear engine beam attachment bolts and washers and
doing an eddy current inspection of all the attachment bolt holes. If
the bolt holes are found damaged during the eddy current inspection,
the damage will vary considerably from airplane to airplane, and the
FAA has no way of estimating a repair cost. In addition, the FAA has no
way of determining the number of aircraft that might need these
actions.

The FAA has included all known costs in this 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

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: