DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0194; Directorate Identifier 2017-CE-006-AD;
Amendment 39-18915; AD 2017-11-16]
RIN 2120-AA64

Airworthiness Directives; PILATUS AIRCRAFT LTD. Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for PILATUS
AIRCRAFT LTD. Model PC-12/47E airplanes. This AD results from mandatory
continuing airworthiness information (MCAI) issued 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 an error within the flight management system caused by
installing Primus APEX software Build 10 or 10.9, which could cause
deviation from the correctly calculated barometric vertical navigation
nominal glide path. We are issuing this AD to require actions to
address the unsafe condition on these products.

DATES: This AD is effective July 13, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in the AD as of July 13,
2017.

ADDRESSES: You may examine the AD docket on the Internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2017-
0194; or in person at Document Management Facility, 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 service information identified in this AD, 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; Internet: www.pilatus-aircraft.com.
You may view this referenced service information at the FAA, Small
Airplane Directorate, 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 http://www.regulations.gov by
searching for Docket No. FAA-2017-0194.

FOR FURTHER INFORMATION CONTACT: Doug Rudolph, Aerospace Engineer, FAA,
Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri
64106; telephone: (816) 329-4059; fax: (816) 329-4090; email:
doug.rudolph@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to PILATUS AIRCRAFT LTD. Model
PC-12/47E airplanes. The NPRM was published in the Federal Register on
March 21, 2017 (82 FR 14488). The NPRM proposed to correct an unsafe
condition for the specified products and was based on mandatory
continuing airworthiness information (MCAI) originated by an aviation
authority of another country. The MCAI states:

An occurrence was reported of a split between the vertical
guidance data and the flight director steering commands during a
Vertical Glide Path (VGP) approach. Subsequent investigation
identified an error within the Flight Management System (FMS) that
was introduced into Primus APEX software (S/W) Build 10 and S/W
Build 10.9.
This condition, if not corrected, could lead to loss of control
of the aeroplane.
To address this potential unsafe condition, Pilatus issued
Temporary Revision (TR) No. 38 to the PC-12/47E Pilot's Operating
Handbook, (POH) Report No: 02277 (hereafter referred to as ``POH TR
38'' in this AD), limiting VGP Approach mode sourced on baro
Vertical Navigation (VNAV) to visual meteorological conditions (VMC)
only, and providing procedures applicable in case of VGP deviation
occurring during baro VNAV approaches.
For the reason described above, this [EASA] AD requires
amendment of the applicable Aircraft Flight Manual (AFM).

The MCAI can be found in the AD docket on the Internet at https://www.regulations.gov/document?D=FAA-2017-0194-0002.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comment received on the proposal
and the FAA's response to the comment.

Request To Clarify the Unsafe Condition

Johan Kruger of PILATUS AIRCRAFT LTD. stated that in the Discussion
section and the Reason section (paragraph (e)) of the proposed AD, it
is stated that the unsafe condition may result in loss of control due
to following incorrect data from the flight management system. The
commenter stated that the loss of control statement may be misleading.
The commenter further stated that the autopilot fails to follow the
correctly indicated nominal vertical flight path. If the pilot does not
observe the indicated vertical deviation, which is the pilot's primary
duty during instrument meteorological conditions (IMC) final approach,
it could result in the pilot losing situational awareness. In a worst
case scenario, the airplane would descent towards terrain and
ultimately, if no attention is given to terrain awareness and warning
system (TAWS) call outs, collide with the terrain--potential controlled
flight into terrain (CFIT).
The commenter requested that the last sentence of paragraph (e) be
changed to read: ``We are issuing this AD to prevent the pilot from
following incorrect data from the flight management system, which could
result in the loss of situational awareness.''
We agree with the commenter and have changed the AD based on this
comment.

Conclusion

We reviewed the relevant data, considered the comment received, and
determined that air safety and the public interest require adopting the
AD with the change described previously and minor editorial changes. We
have determined that these minor changes:

- Are consistent with the intent that was proposed in
the NPRM for correcting the unsafe condition; and
- Do not add any additional burden upon the public than was
already proposed in the NPRM.
We also determined that these changes will not increase the
economic burden on any operator or increase the scope of the AD.

Related Service Information Under 1 CFR Part 51

We reviewed PILATUS AIRCRAFT LTD. Temporary Revision No. 38 to PC-
12/47E Pilot's Operating Handbook, Airplane Flight Manual 02277,
Section 2--Limitations, Report No: 02277, dated February 8, 2017. The
service information describes procedures for limiting the use of the
autopilot and flight director to day visual meteorological conditions
(VMC) during barometric vertical navigation (baro VNAV) during a
vertical glide path approach (VGP). 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 of this AD.

Costs of Compliance

We estimate that this AD will affect 350 products of U.S. registry.
We also estimate that it will take about 1 work-hour per product to
comply with the basic requirements of this AD. The average labor rate
is $85 per work-hour.
Based on these figures, we estimate the cost of this AD on U.S.
operators to be $29,750, or $85 per product.

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.
We are 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

We determined that 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2017-0194;
or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains the NPRM, the regulatory evaluation, any comments received,
and other information. The street address for the Docket Office
(telephone (800) 647-5527) is in the ADDRESSES section. Comments will
be available in the AD docket shortly after receipt.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of 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 AD: