DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0573; Project Identifier 2018-CE-046-AD]
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 Pilatus Aircraft Ltd. (Pilatus) Models PC-12/45, PC-12/47, and PC-
12/47E airplanes with Supplemental Type Certificate (STC) SA00634DE
installed. This proposed AD was prompted by a report of strake
attachment brackets and the fuselage frame failing at the upper most
bracket attachment location. This proposed AD would require inspecting
the strake, attachment brackets, surrounding structure, and bolts and
replacing components and repairing damage if 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 September
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
Business Aircraft Ltd., Customer Support Department, 12300 Pilatus Way,
Broomfield, CO 80021; phone: (866) 721-2435; fax: (303) 465-9099;
email: firstname.lastname@example.org. 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.
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0573; 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: Richard R. Thomas, Aviation Safety
Engineer, Denver ACO Branch, FAA, 26805 E 68th Avenue, Denver, CO
80249; phone: (303) 342-1080; fax: (303) 342-1088; email: 9-Denver-Aircraft-Cert@faa.gov.
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-2021-0573; Project Identifier
2018-CE-046-AD'' 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
Richard R. Thomas, Aviation Safety Engineer, Denver ACO Branch, FAA,
26805 E 68th Avenue, Denver, CO 80249. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.
The FAA received a report that an operator found that one of the
fuselage strakes was ``loose having excess play'' on two different
Pilatus Model PC-12/47E airplanes. Further inspection found the
fuselage main frame at frame station 40 and the strake attachment
brackets had cracks extending from the attachment bolt hole at the
upper most attachment location. Both airplanes had a SPECTRE Lift
Platform System, STC SA00634DE, installed. The deployment of the lift
platform causes buffeting of the strakes. This condition, if not
addressed, could result in airplane flutter and reduced lateral
stability, which may lead to loss of control of the airplane.
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 Pilatus Service Bulletin PC-12 Series, Report
Number 12-1700-64-0000, Revision B, dated August 10, 2018 (Pilatus
Report 12-1700-64-0000B), which contains procedures for inspection of
all fuselage strake attachment bolts and the surrounding structure.
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.
Proposed AD Requirements in This NPRM
This proposed AD would require inspecting the strake, attachment
brackets, and bolts for movement and damage, both internal and
external, and replacing or repairing any damaged parts.
Differences Between This Proposed AD and the Service Information
Pilatus Report 12-1700-64-0000B specifies a one-time inspection
within 10 flight hours of issuance of the SB and recommends repeat
inspections without specifying an inspection interval. This
proposed AD would require repeating the inspection every 150 flight
hours. Pilatus Report 12-1700-64-0000B specifies contacting Pilatus for
further instructions. This proposed AD would require using an FAA-
approved repair method. Pilatus Report 12-1700-64-0000B applies to
Pilatus PC-12 aircraft serial numbers 190 to 1575. This proposed AD
would apply to all Pilatus Aircraft Ltd. Models PC-12/45, PC-12/47, and
PC-12/47E airplanes, regardless of serial number, if STC SA00634DE is
The FAA considers this AD an interim action. Pilatus is working on
a modification with the intent of minimizing, if not eliminating, the
buffeting of the strakes. Once this action is developed, approved, and
available, the FAA may consider additional rulemaking.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 30 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
COST PER PRODUCT
COST ON U.S. OPERATORS
|Inspection of the strake assemblies.
|| 1 work-hour x $85 per hour = $85 per inspection cycle.
|| Not applicable.
|| $85 per inspection cycle.
|| $2,550 per inspection cycle.
The extent of damage found during the proposed inspections may vary
considerably from airplane to airplane. The FAA has no way of knowing
how many airplanes may have damage or the extent of damage each
airplane may have.
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.
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
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