[Federal Register Volume 82, Number 135 (Monday, July 17, 2017)]
[Rules and Regulations]
[Pages 32616-32618]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-14936]



Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2017-0702; Special Conditions No. 23-282-SC]

Special Conditions: Pilatus Aircraft Ltd., PC-24; Electronic 
Engine Control (EEC)

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 
features associated with installation of an electronic engine control. 
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 beginning July 6, 2017.

ADDRESSES: Send comments identified by docket number FAA-2017-0702 
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 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-
23-267-SC.............................  Cirrus Design Corporation/Model
23-268-SC.............................  Korean Aircraft Industries/Model

Comments Invited

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

    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.
    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 9th 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 and Instrument Flight Rules and approval for 
flight into known icing.
    The PC-24 airplane's two Williams International FJ44-4A turbofan 
engines each use an electronic engine control system (EEC)--commonly 
referred to as a Full Authority Digital Engine Control (FADEC)--instead 
of a traditional mechanical control system. Even though the engine 
control system will be certificated as part of the engine, the 
installation of an engine with an electronic control system requires 
evaluation due to critical environmental effects and possible effects 
on or by other airplane systems. Examples of critical environmental 
effects include--
     Indirect effects of lightning;
     Radio interference with other airplane electronic systems; 

[[Page 32617]]

     Shared engine, airplane data, and power sources.
    The regulatory requirements in part 23 for evaluating the 
installation of complex systems--including electronic systems and 
critical environmental effects--are contained in Sec. Sec.  23.1306, 
23.1308, and 23.1309. However, when Sec.  23.1309 was published, the 
use of electronic control systems for engines was not envisioned. The 
integral nature of these systems makes it necessary to properly 
evaluate the airplane functions included in the EEC and ensure the 
installation does not degrade the EEC reliability, both of which are 
approved under 14 CFR part 33. Sections 23.1306(a) and 23.1308(a) apply 
to the EEC to ensure it remains equivalent to a mechanical system, 
which is not generally susceptible to the HIRF and lightning 
    In some cases, the airplane--in which the engine is being 
installed--will determine a higher classification than the engine 
controls are certificated for; requiring the EEC systems be analyzed at 
a higher classification. As of November 2005, EEC special conditions 
mandated the Sec.  23.1309 classification for loss of EEC control as 
catastrophic for any airplane. This is not to imply an engine failure 
is classified as catastrophic, but that the EEC must provide an 
equivalent reliability to mechanical engine controls. In addition, 
Sec. Sec.  23.1141(e) and 25.901(b)(2) are applied to provide the fault 
tolerant design requirements of turbine engine mechanical controls to 
the EEC and ensure adequate EEC inspection and maintenance intervals.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Pilatus Aircraft Ltd., must 
show that the PC-24 meets the applicable provisions of part 23, as 
amended by amendments 23-1 through 23-62 thereto.
    If the Administrator finds that 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 
emission 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 
    Electronic Engine Control System.


    As discussed in the ``Background'' section, the PC-24 will use an 
EEC system instead of a traditional mechanical control 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 a structured assessment to determine 
potential installation issues mitigates the concerns that the addition 
of an electronic engine control may produce failure conditions not 
previously considered.


    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. Electronic Engine Control.
    (a) For electronic engine control system installations, it must be 
established that no single failure or malfunction or probable 
combinations of failures of EEC system components will have an effect 
on the system--as installed in the airplane--that causes the loss-of-
thrust-control (LOTC) probability of the system to exceed those allowed 
in part 33 certification.
    (b) Electronic engine control system installations must be 
evaluated for environmental and atmospheric conditions, including 
lightning. The EEC system lightning and HIRF effects that result in 
LOTC should be considered catastrophic.
    (c) The components of the installation must be constructed, 
arranged, and installed to ensure their continued safe operation 
between normal inspections or overhauls.
    (d) Functions incorporated into any electronic engine control that 
make it part of any equipment, system, or installation whose functions 
are beyond that of basic engine control, and which may also introduce 
system failures and malfunctions, are not exempt from Sec.  23.1309 and 
must be shown to meet part 23 levels of safety as derived from Sec.  
23.1309. Part 33 certification data--if applicable--may be used to show 
compliance with any part 23 requirements. If part 33 data is to be used 
to substantiate compliance with part 23 requirements, then the 
applicant must provide this data to show compliance.

    Note: The term ``probable'' in the context of ``probable 
combination of failures'' does not have the same meaning as in AC 
23.1309-1E, ``System Safety Analysis and

[[Page 32618]]

Assessment for Part 23 Airplanes.'' The term ``probable'' in 
``probable combination of failures'' means ``foreseeable,'' or--in 
AC 23.1309-1E terms--``not extremely improbable.''

    Issued in Kansas City, Missouri on July 6, 2017.
Kelly Broadway,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
[FR Doc. 2017-14936 Filed 7-14-17; 8:45 am]