
[Federal Register Volume 82, Number 105 (Friday, June 2, 2017)]
[Rules and Regulations]
[Pages 25509-25511]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-11347]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2017-0290; Special Conditions No. 23-281-SC]


Special Conditions: Pilatus Aircraft Limited Models PC-12, PC-12/
45, PC-12/47; Autothrust System

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special condition.

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SUMMARY: This special condition is for the Pilatus Aircraft Limited PC-
12, PC-12/45, and PC-12/47 airplanes. These airplanes, as modified by 
Innovative Solutions & Support, Inc., will have a novel or unusual 
design feature associated with the use of an autothrust system. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. This special 
condition contains the additional safety standards the Administrator 
considers necessary to establish a level of safety equivalent to that 
established by the existing airworthiness standards.

DATES: This special condition is effective June 2, 2017 and is 
applicable beginning May 24, 2017.

FOR FURTHER INFORMATION CONTACT: Jeff Pretz, Federal Aviation 
Administration, Small Airplane Directorate, Aircraft Certification 
Service, 901 Locust, Room 301, Kansas City, MO 64106; telephone (816) 
329-3239; facsimile (816) 329-4090.

SUPPLEMENTARY INFORMATION:

Background

    On April 4, 2016, Innovative Solutions & Support applied for a 
supplemental type certificate for installation of an autothrust system 
in the PC-12, PC-12/45, and PC-12/47 airplanes. The autothrust system 
is capable of setting forward thrust based on operation in either a 
pilot selectable torque or airspeed mode. Operation is limited to use 
only when above 400 feet above ground level (AGL) after takeoff, and 
requires disengagement at decision height (DH) or minimum decision 
altitude (MDA) on approach. The PC-12, PC-12/45, and PC-12/47 airplanes 
are nine-passenger, two-crewmember, single-engine turbo-propeller 
airplanes with a 30,000-foot service ceiling and a maximum takeoff 
weight of 9,039 to 10,450 pounds--depending on airplane model. These 
airplanes are powered by a single Pratt & Whitney PT6A-67 engine.
    The Innovative Solutions & Support, Inc., modification installs an 
autothrust system in the PC-12, PC-12/45, and PC-12/47 airplanes to 
reduce pilot workload. The autothrust system is useable in all phases 
of flight from 400 feet AGL after takeoff down to the decision height 
on approach. The system includes a torque and airspeed mode along with 
monitors to prevent the system from exceeding critical engine or 
airspeed limits. A stepper motor provides throttle movement by acting 
through a linear actuator, which acts as a link between the stepper 
motor and throttle. The pilot can override the linear actuator by 
moving the throttle, which automatically disengages the autothrust 
system upon disagreement in the expected throttle position versus the 
actual position.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Innovative Solutions & 
Support must show that the PC-12, PC-12/45, and PC-12/47 airplanes, as 
changed, continues to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A78EU. The 
regulations incorporated by reference in the type certificate are 
commonly referred to as the ``original type certification basis.'' The 
regulations incorporated by reference in A78EU are as follows: 14 CFR 
part 23, amendments 23-1 through 23-42.\1\
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    \1\ See Type Certification Data Sheet A78EU, revision 25, 
``Certification Basis'' section for the PC-12, PC-12/45, and PC-12/
47 full certification basis. (http://rgl.faa.gov/.)
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    If the Administrator finds the applicable airworthiness regulations 
(i.e., 14 CFR part 23) do not contain adequate or appropriate safety 
standards for the PC-12, PC-12/45, and PC-12/47 airplanes because of a 
novel or unusual design feature(s), special conditions are prescribed 
under the provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the PC-12, PC-12/45, and PC-12/47 airplanes must comply 
with the fuel vent and exhaust emission requirements of 14 CFR part 34 
and the noise certification requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38 and they become part of the type 
certification basis under Sec.  21.101. Special conditions are 
initially applicable to the model for which they are issued. Should the 
applicant apply for a supplemental type certificate to modify any other 
model included on the

[[Page 25510]]

same type certificate to incorporate the same novel or unusual design 
feature, the FAA would apply these special conditions to the other 
model under Sec.  21.101.

Novel or Unusual Design Features

    The PC-12, PC-12/45, and PC-12/47 airplanes will incorporate the 
following novel or unusual design feature:

Autothrust system

Discussion

    As discussed in the summary section, this modification makes use of 
an autothrust system, which is a novel design for this type of 
airplane. The applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for this design feature. 
Mandating additional requirements--developed in part--by adapting 
relevant portions of 14 CFR 25.1329, Flight guidance systems--
applicable to autothrust systems--along with FAA experience with 
similar autothrust systems, mitigates the concerns associated with 
installation of the proposed autothrust system.
    The FAA has previously issued this proposed special condition to 
part 23 turbojet airplanes, but not for turbo-propeller airplanes. The 
PC-12, PC-12/45, and PC-12/47 airplanes are unique with respect to 
other turbo-propeller designs in that the basic design does not include 
a separate propeller control lever. Future use of these special 
conditions on other turbo-propeller designs will require evaluation of 
the engine and propeller control system to determine their 
appropriateness.

Discussion of Comments

    Notice of proposed special conditions No. 23-17-01-SC for the 
Pilatus Aircraft Limited PC-12, PC-12/45, and PC-12/47 airplanes was 
published in the Federal Register on April 14, 2017 (82 FR 17943).\2\ 
No comments were received, and the special condition is adopted as 
proposed.
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    \2\ Refer to the U.S. Government Printing Office at https://www.gpo.gov/.
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Applicability

    As discussed above, this special condition is applicable to the PC-
12, PC-12/45, and PC-12/47 airplanes. Should Innovative Solutions & 
Support, Ltd. apply at a later date for a supplemental type certificate 
to modify any other model included on Type Certificate No. A78EU to 
incorporate the same novel or unusual design feature, the FAA would 
apply these special conditions to that model as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register; however, as the certification date for the STC for 
the Pilatus Aircraft, Ltd., PC-12, PC-12/45, and PC-12/47 airplanes is 
imminent, pursuant to 5 U.S.C. 553(d), the FAA finds that good cause 
exists to make this special condition effective upon issuance.

Conclusion

    This action affects only certain novel or unusual design features 
on PC-12, PC-12/45, and PC-12/47 airplanes. It is not a rule of general 
applicability and affects only the applicant who applied to the FAA for 
approval of these features on the airplane.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

Citation

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(f), 106(g); 40113 and 44701; 14 CFR 
21.16 and 21.101; and 14 CFR 11.38 and 11.19.

The Special Condition

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special condition is issued as part of the 
type certification basis for Pilatus Aircraft Ltd., PC-12, PC-12/45, 
and PC-12/47 airplanes modified by Innovative Solutions & Support, Inc.

1. Autothrust System

    In addition to the requirements of Sec. Sec.  23.143, 23.1309, and 
23.1329, the following apply:
    (a) Quick disengagement controls for the autothrust function must 
be provided for each pilot. The autothrust quick disengagement controls 
must be located on the thrust control levers. Quick disengagement 
controls must be readily accessible to each pilot while operating the 
thrust control levers.
    (b) The effects of a failure of the system to disengage the 
autothrust function when manually commanded by the pilot must be 
assessed in accordance with the requirements of Sec.  23.1309.
    (c) Engagement or switching of the flight guidance system, a mode, 
or a sensor may not cause the autothrust system to affect a transient 
response that alters the airplane's flight path any greater than a 
minor transient, as defined in paragraph (l)(1) of this special 
condition.
    (d) Under normal conditions, the disengagement of any automatic 
control function of a flight guidance system may not cause a transient 
response of the airplane's flight path any greater than a minor 
transient.
    (e) Under rare normal and non-normal conditions, disengagement of 
any automatic control function of a flight guidance system may not 
result in a transient any greater than a significant transient, as 
defined in paragraph (l)(2) of this special condition.
    (f) The function and direction of motion of each command reference 
control, such as heading select or vertical speed, must be plainly 
indicated on--or adjacent to--each control if necessary to prevent 
inappropriate use or confusion.
    (g) Under any condition of flight appropriate to its use, the 
flight guidance system may not produce hazardous loads on the airplane, 
nor create hazardous deviations in the flight path. This applies to 
both fault-free operation and in the event of a malfunction, and 
assumes that the pilot begins corrective action within a reasonable 
time.
    (h) When the flight guidance system is in use, a means must be 
provided to avoid excursions beyond an acceptable margin from the speed 
range of the normal flight envelope. If the airplane experiences an 
excursion outside this range, a means must be provided to prevent the 
flight guidance system from providing guidance or control to an unsafe 
speed.
    (i) The flight guidance system functions, controls, indications, 
and alerts must be designed to minimize flightcrew errors and confusion 
concerning the behavior and operation of the flight guidance system. A 
means must be provided to indicate the current mode of operation, 
including any armed modes, transitions, and reversions. Selector switch 
position is not an acceptable means of indication. The controls and 
indications must be grouped and presented in a logical and consistent 
manner. The indications must be visible to each pilot under all 
expected lighting conditions.
    (j) Following disengagement of the autothrust function, a caution 
(visual and auditory) must be provided to each pilot.
    (k) During autothrust operation, it must be possible for the 
flightcrew to move the thrust levers without requiring excessive force. 
The autothrust may not create a potential hazard when the flightcrew 
applies an override force to the thrust levers.
    (l) For purposes of this section, a transient is a disturbance in 
the control or flight path of the airplane that is not

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consistent with response to flightcrew inputs or environmental 
conditions.
    (1) A minor transient would not significantly reduce safety margins 
and would involve flightcrew actions that are well within their 
capabilities. A minor transient may involve a slight increase in 
flightcrew workload or some physical discomfort to passengers or cabin 
crew.
    (2) A significant transient may lead to a significant reduction in 
safety margins, an increase in flightcrew workload, discomfort to the 
flightcrew, or physical distress to the passengers or cabin crew, 
possibly including non-fatal injuries. Significant transients do not 
require--in order to remain within or recover to the normal flight 
envelope--any of the following:
    (i) Exceptional piloting skill, alertness, or strength.
    (ii) Forces applied by the pilot which are greater than those 
specified in Sec.  23.143(c).
    (iii) Accelerations or attitudes in the airplane that might result 
in further hazard to secured or non-secured occupants.

    Issued in Kansas City, Missouri, on May 24, 2017.
Wes Ryan,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-11347 Filed 6-1-17; 8:45 am]
 BILLING CODE 4910-13-P


