Exemption No. 16970 

UNITED STATES OF AMERICA 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

WASHINGTON, DC 20591 

In the matter of the petition of 

CIRRUS DESIGN CORPORATION Regulatory Docket No. FAA-2015-0534 

for an exemption from§ 23.1419(a) of 

Title 14, Code of Federal Regulations 

GRANT OF EXEMPTION 

By letter dated February 27, 2015, Mr. Tom Engelmann, Airworthiness Lead, Cirrus 

Design Corporation, (Cirrus), 4515 Taylor Circle, Duluth, MN 55811 petitioned the Federal 

Aviation Administration (FAA) on behalf of Cirrus for an exemption from§ 23.1419(a) of 

Title 14, Code of Federal Regulations (14 CFR). This exemption, if granted, would exempt 

the model SF50 airplane from the 61-knot stall speed with critical ice accretions. 

The petitioner requests relief from the following regulation: 

Section 23.1419, "Ice Protection", prescribes, in pertinent part, that-

"If certification with ice protection provisions is desired, compliance with the 

requirements of this section and other applicable sections of this part must be 

shown: 

(a) An analysis must be performed to establish, on the basis of the airplane's 

operational needs, the adequacy ofthe ice protection system for the various 

components ofthe airplane. In addition, tests of the ice protection system must 

be conducted to demonstrate that the airplane is capable of operating safely in 

continuous maximum and intermittent maximum icing conditions, as described 

in appendix C of part 25 of this chapter. As used in this section, "Capable of 

operating safely" means that airplane performance, controllability, 

maneuverability, and stability must not be less than that required in part 23, 

subpart B." 

ACE-16-000 1-E 
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The petitioner supports its request with the following information: 

Public Interest 

"The SF50 is primarily used for cross-country travel and has a high probability of 

encountering inclement weather- including icing conditions. Increasing the flight 

envelope ofthe SF50 to include flight in icing conditions provides a significant 

increase in safety for SF50 operators-especially those who inadvertently encounter 

icing conditions. The associated design features required to make flight in icing 

operations possible adds a significant level of redundancy and increased system 

capability over the existing design. Also, the flight testing required for this design 

change will fully prove out the capability of this system and shown that operational 

safety will have been increased. 

Thus, granting this exemption would be in the public interest due to the increased 

safety associated with the operational envelope expansion without negatively impacting 

aircraft utility." 

Safety Affect 

"The following compensating features, as described in AC 23.1419-2D, will ensure the 

level of safety will not be adversely affected by this exemption. 

1. The airplane with critical ice accretions as defined in paragraph 13.b. of this AC 

complies with the stall warning requirements of§ 23.207. 

The SF50 maintains the required stall margin and does not cause nuisance warnings 

as required by § 23.207. This will be shown by flight test and documented in the 

flight test reports submitted to the FAA. 

2. The AFM performance data in icing conditions reflects the higher stall and operating 

speeds. 

The AFM supplement for flight in icing equipped airplanes includes the 

performance data to be used when flying in icing conditions and/or with known 

aircraft ice accretions. These speeds have been determined by flight test and 

documented in the flight test reports submitted to the FAA. 

3. The airplane with critical ice accretions has acceptable stall characteristics and is 

safely controllable with normal piloting skill as required by § 23.201 and§ 23.203. 

Flight testing with simulated critical ice accretions was accomplished showing 

acceptable stall characteristics as required by§ 23.201 and§ 23.203 and accounting 

for normal piloting skill as required by § 23 .141 . This was documented in the flight 

test reports submitted to the FAA. 
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4. The tire requirements of§ 23 .733 and brake requirements of§ 23.735 are met with 

the higher stall and operating speeds. 

Cirrus has shown that the existing tires and brake system will meet the requirements 

of§ 23.733 and§ 23 .735, respectively. This was shown by analysis and documented 

in the design report submitted to the FAA. 

5. The ground handling requirements of§ 23.231, § 23.233 and§ 23.235 are met with 

higher landing speeds. 

Cirrus conducted ground handling tests during the simulated ice shape flight tests 

and found no adverse handling characteristics. 

6. All other airplane system or testing requirements that could be affected by higher 

operating speeds, such as autopilot and flight director gains are evaluated. 

The autopilot and flight director were evaluated during the flight test program and 

documented in the natural icing flight test report submitted to the FAA. 

7. Each seat/restraint system would have to include a safety belt and shoulder harness 

with a metal-to-metal latching device. 

The SF50 utilizes a seat restraint system that includes safety belts and shoulder 

harnesses with metal-to-metal latching devices for all seven pilot/occupant seats. 

8. The airplane certification basis would have to include § 23.1 091 at amendment 23-

51 and§ 23.1093 at amendment 23-51 to provide the latest regulations for engine 

operation in icing conditions. 

The certification basis for the SF50 was established at amendment 23-62 and 

includes § 23.1091 and § 23.1093 at amendment 23-51. Compliance for each of 

these regulations will be addressed as part of this type certification project and 

documented in the design report submitted to the FAA. 

9. The airplane certification basis would have to include § 23.995 at amendment 23-29. 

The certification basis for the SF50 was established at amendment 23-62 and 

includes§ 23.995 at amendment 23-29. The existing compliance shown for this 

regulation was not affected by this type design change." 

A summary of the petition was published in the Federal Register on April 12, 2016 

(81 FR 21646). No comments were received. 

The FAA's analysis is as follows: 

The FAA finds that the model SF 50 incorporates the compensating features listed in 

Advisory Circular 23.1419-20, Certification of Part 23 Airplanes for Flight in Icing 
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Conditions, with the exception that the airplane with no ice accretions does not meet the 61 

knot stall speed requirement of§ 23.49, Stalling speed, paragraph (c). This is acceptable, 

since the most critical compensating feature of stall warning with critical ice accretions is 

provided. The FAA also finds that pilot type rating training per § 61.31, Type rating 

requirements, additional training, and authorization requirements, paragraph (h), must address 

the pertinent aspects of the higher stall warning, stall, and operating speeds in icing 

conditions. 

The FAA's Decision 

In consideration of the foregoing, I find that a grant of exemption is in the public interest. 

Therefore, pursuant to the authority contained in 49 U.S.C. §§ 106(f), 40113 and 44701 , 

delegated to me by the Administrator, Cirrus Design Corporation is granted an exemption 

from 14 CFR § 23.1419(a) to the extent necessary to allow Cirrus to exempt the model SF50 

airplane from the 61-knot stall speed with critical ice accretions, subject to the conditions and 

limitations listed below. 

Conditions and Limitations 

1. Cirrus Design Corporation must ensure that type rating training includes the 

following: 

a) AFM Limitations/Procedures for Activation of Ice Protection 

b) Stall Warning/Stick Pusher 

i. Why activating ice protection system is important-ice has significant increase 

in stall speed, stall warning speed needs to be increased. 

ii. Increased icing speeds, and stall warning and stick pusher schedule. 

c) Icing encounter on approach 

i. Cirrus must determine a procedure if icing is encountered on approach or 

landing phase of flight. 

ii. For airplanes with large stall warning/stick pusher schedule change for icing or 

single pilot airplanes, if icing conditions are anticipated or possible at 

destination, activate ice protection prior to configuring for approach. 

d) Performance 

i. Landing distance required with increased icing speeds 

ii. Weight limits in icing (if applicable) 
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iii. If icing conditions are anticipated or possible at destination, consider 

performance in pre-flight planning. 

Issued in Kansas City, MO, on June 23, 2016. 

wifi~S~ William Schinstock 

Acting Manager, Small Airplane Directorate 

Aircraft Certification Service 
Project No.: ACE-16-0001-E 

Project Officer: Paul Pellicano 

ACE-111 :TTompkins:01/27/16:Doc#61452 

[Insert Stylewriter Score Here] 

Tom Engelmann 

Lead Airworthiness 

Cirrus Design Corporation 

4515 Taylor Circle 

Duluth, MN 55811 

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