[Federal Register Volume 82, Number 135 (Monday, July 17, 2017)]
[Rules and Regulations]
[Pages 32618-32620]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-14938]



Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2017-0703; Special Conditions No. 23-283-SC]

Special Conditions: Pilatus Aircraft Ltd., PC-24, Autothrust 

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.


SUMMARY: These special conditions are issued for the Pilatus Aircraft 
Ltd. PC-24 airplane. This airplane will have a novel or unusual design 
feature associated with installation of an autothrust system. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. These special 
conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

DATES: These special conditions are effective July 17, 2017, and are 
applicable July 6, 2017.

ADDRESSES: Send comments identified by docket number FAA-2017-0703 
using any of the following methods:
    [squ] Federal eRegulations Portal: Go to http://www.regulations.gov 
and follow the online instructions for sending your comments 
    [squ] Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
    [squ] Hand Delivery of Courier: Take comments to Docket Operations 
in Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE., Washington, DC, between 9 a.m., and 5 p.m., Monday through 
Friday, except Federal holidays.
    [squ] Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://regulations.gov, including any personal information 
the commenter provides. Using the search function of the docket Web 
site, anyone can find and read the electronic form of all comments 
received into any FAA docket, including the name of the individual 
sending the comment (or signing the comment for an association, 
business, labor union, etc.). DOT's complete Privacy Act Statement can 
be found in the Federal Register published on April 11, 2000 (65 FR 
19477-19478), as well as at http://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the Docket Operations in Room W12-140 
of the West Building Ground Floor at 1200 New Jersey Avenue SE., 
Washington, DC, between 9 a.m., and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Jeff Pretz, ACE-111, Federal Aviation 
Administration, Small Airplane Directorate, Aircraft Certification 
Service, 901 Locust Street, Kansas City, MO 64106; telephone (816) 329-
3239; facsimile (816) 329-4090.

SUPPLEMENTARY INFORMATION: The FAA has determined, in accordance with 5 
U.S.C. 553(b)(3)(B) and 553(d)(3), that notice and opportunity for 
prior public comment hereon are unnecessary because the substance of 
these special conditions has been subject to the public comment process 
in several prior instances with no substantive comments received. The 
FAA therefore finds that good cause exists for making these special 
conditions effective upon issuance.

       Special condition No.\2\              Company/airplane model
23-264-SC.............................  Honda Aircraft Company/Model HA-
23-272-SC.............................  Cirrus Design Corporation/Model
23-281-SC.............................  Innovative Solutions and Support
                                         Inc./Pilatus Aircraft Ltd., PC-
                                         12 Models.

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special conditions, explain the 
reason for any recommended change, and include supporting data. We ask 
that you send us two copies of written comments.

    \2\ See http://rgl.faa.gov/ to review the listed special 

    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions based on the comments we receive.


    On July 9, 2012, Pilatus Aircraft Ltd. applied for a type 
certificate for their new PC-24 airplane. The PC-24 is an aluminum 
pressurized low-wing business jet with a T-tail configuration and 
retractable undercarriage designed to meet the commuter category 
requirements of part 23. Two Williams International FJ44-4A turbofan 
engines rated at 3,400 pounds (lbs.) of take-off thrust, situated in 
nacelles on each side of the rear fuselage power the PC-24. The PC-24 
will have a Maximum Take-off Weight (MTOW) of 17,200 pounds (7,802 
kilograms). It has a maximum seating capacity of up to ten passengers 
and one or two pilots. The airplane will be certificated for day and 
night Visual Flight Rules, Instrument Flight Rules and flight into 
known icing.
    The PC-24 is equipped with an autothrust system--also referred to 
as an autothrottle system. The autothrust system is useable in all 
phases of flight from takeoff to decision height on approach. The 
system includes speed and thrust modes along with monitors to prevent 
the system from exceeding engine or airspeed limits. A servo provides 
throttle movement, which is part of each throttle quadrant assembly. 
The servo(s) can be overridden by pilot force or disconnected using the 
autothrottle quick disconnect switch on either thrust control lever, 
the autopilot quick disconnect switch on the yoke, or the autothrottle 
control switch on the flight guidance panel.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Pilatus Aircraft Ltd. must 
show the PC-24 meets the applicable provisions of part 23, as amended 
by amendments 23-1 through 23-62 thereto.
    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-24 because of a novel or unusual design feature, 
special conditions are prescribed under the provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the PC-24 must comply with the fuel vent and exhaust 

[[Page 32619]]

requirements of 14 CFR part 34, the noise certification requirements of 
14 CFR part 36, and the FAA must issue a finding of regulatory adequacy 
pursuant to section 611 of Public Law 92-574, the ``Noise Control Act 
of 1972.''
    The FAA issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38 and they become part of the type certification basis under 
Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, the FAA would apply these special conditions to 
the other models under Sec.  21.101.

Novel or Unusual Design Features

    The PC-24 will incorporate the following novel or unusual design 

Autothrust System


    As discussed in the ``Background'' section, the PC-24 will 
incorporate an autothrust system, which is considered 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 the relevant portions 14 CFR 25.1329 (automatic pilot systems) 
applicable to the autothrust system--along with FAA experience with 
similar autothrust systems. This additional requirement mitigates the 
concerns associated with installation of the autothrust system.


    As discussed above, these special conditions are applicable to the 
PC-24. Should Pilatus Aircraft Ltd. apply at a later date for a change 
to the type certificate to include another model on the same type 
certificate incorporating the same novel or unusual design feature, the 
FAA would apply these special conditions to that model as well.


    This action affects only certain novel or unusual design features 
on one model of airplanes. It is not a rule of general applicability 
and it affects only the applicant who applied to the FAA for approval 
of these features on the airplane.
    The substance of these special conditions has been subjected to the 
notice and comments period in several prior instances--identified 
above--and has been derived without substantive change from those 
previously issued. It is unlikely that prior public comment would 
result in a significant change from the substance contained herein. 
Therefore, notice and opportunity for prior public comments hereon are 
unnecessary and the FAA finds good cause, in accordance with 5 U.S.C. 
553(b)(3)(B) and 553(d)(3), making these special conditions effective 
upon issuance. The FAA is requesting comments to allow interested 
persons to submit views that may not have been submitted in response to 
the prior opportunities for comment described above.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.


    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 21.17; and 14 CFR 11.38 and 11.19.

The Special Conditions

Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Pilatus Aircraft Ltd. PC-24 airplanes.
    1. Autothrust System.
    For autothrust systems, 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 auto thrust 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 
    (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 
    (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 period of 
    (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 
    (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. 
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 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

[[Page 32620]]

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 July 6, 2017.
Kelly Broadway,
Acting Manager, Small Airplane Directorate Aircraft Certification 
[FR Doc. 2017-14938 Filed 7-14-17; 8:45 am]