### Exemption No. 16970 UNITED STATES OF AMERICA DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION WASHINGTON, DC 20591

In the matter ofthe petition of CIRRUS DESIGN CORPORATION Regulatory Docket No. FAA-2015-0534 

### for an exemption from§ 23.1419(a) of Title 14, Code ofFederal 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 behalfofCirrus for an exemption from§ 23.1419(a) of Title 14, Code ofFederal Regulations (14 CFR). This exemption, ifgranted, would exempt the model SF50 airplane from the 61-knot stall speed with critical ice accretions. The petitioner requests relieffrom the following regulation: Section 23.1419, 

### "Ice Protection", prescribes, in pertinent part, that- "Ifcertification with ice protection provisions is desired, compliance with the requirements ofthis section and other applicable sections ofthis part must be shown: (a) An 

### analysis must be performed to establish, onthe basis ofthe airplane's operational needs, the adequacy ofthe ice protection system for the various components ofthe airplane. In addition, tests ofthe ice protection system must be conducted to demonstrate that the airplane is capable ofoperating safely in continuous maximum and intermittent maximum icing conditions, as described in appendix C ofpart 25 ofthis 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-16-0001-E2 

### 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-especiallythose who inadvertently encounter icing conditions

. The associated design features required to make flight in icing operations possible adds a significant level ofredundancy and increased system capability overthe existing design. Also, the flight testing required for this design change will fully prove out the capability ofthis 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 withthe 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 ofsafety will not be adversely affected by this exemption. 1. The airplane with critical ice accretions as defined inparagraph 13.b. ofthis 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 shownby flight test and documented inthe 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 datato be used when flying in icing conditions and/or with known aircraft ice accretions. These speeds have been determined by flight test and documented inthe 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

.3 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 ortesting 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 § 23.1091 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 ofthis type certificationproject and documented in the design report submitted to the FAA. 9. The airplane certificationbasis 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 ofthe 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 SF50 incorporates the compensating features listed in Advisory Circular 23.1419-20, Certification ofPart 23 Airplanes for Flight in Icing4 Conditions, with the exceptionthat the airplane with no ice accretions does notmeetthe 61 knot stall speed requirement of§ 23.49, Stalling speed, paragraph (c). This is acceptable, since the most critical compensating feature ofstall warning with critical ice accretions is provided. The FAA also finds thatpilot type rating trainingper § 61.31, Type rating requirements, additional training, and authorization requirements, paragraph (h), must address the pertinent aspects ofthe higher stall warning, stall, and operating speeds in icing conditions. 

### The 

### FAA's Decision In consideration ofthe foregoing, I find that a grant ofexemptionis inthe public interest. Therefore, pursuantto the authority contained in49 U
.S.C. §§ 106(f), 40113 and 44701 , delegated to me bythe Administrator, Cirrus Design Corporation is granted an exemption from 14 CFR § 23
.1419(a)to the extent necessary to allow Cirrus to exemptthe model SF50 airplane from the 61-knot stall speed with critical ice accretions, subjectto the conditions and limitations listed below. 

### Conditions and Limitations 1. Cirrus Design Corporationmustensure thattype rating training includes the following: a) AFM Limitations/Procedures for Activation ofIce Protection b) Stall Warning/Stick Pusher i. Why activating ice protection system is important-icehas significant increase

in stall speed, stall warning speedneeds to be increased

. ii. Increased icing speeds, and stall warning and stickpusher schedule. c) Icing encounter on approach i. Cirrus must determine a procedure ificing is encountered on approach or

landing phase offlight. ii. For airplanes with large stall warning/stick pusher schedule change for icing or single pilotairplanes, ificing conditions are anticipated orpossible at destination, activate ice protectionpriorto configuring for approach. d) Performance i. Landing distance required with increased icing speeds ii. Weight limits inicing (if applicable)5 

### iii. Ificing 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

### ProjectNo.: 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 6