27 July 2012 

IN REPLY, REFER TO: 

L390-12-1608 

U.S Department of Transportation 

Docket Operations 

_;~cP.~RTMENT OF ~ ··./-!.NSPORTATION 

'-:.:1\ET OPERATIONS 

ZG ll JUL 3 1 A 1 1 : 0 S 

West Building Ground Floor, Room W12-140 

1200 New Jersey Avenue, SE 

Washington, D.C. 20590 

REFERENCE: Petition for Exemption - Stall Speed of 61-knots on the Cessna Model 

T240 CORY ALIS. 

To Whom It May Concern: 

Cessna Aircraft Company requests an exemption to the Stall Speed requirement of 14 CPR 

§23.1419(a) Arndt 43, as part of the Flight Into Known Icing (FIKI) major type design change to 

the Cessna Model T240 COR VALIS. This type design change is currently OPEN with the 

Wichita ACO under FAA project TD5550WI-A. The exemption is being requested since the 

Cessna Model T240 Corvalis will not meet the 61-knot stall speed requirement with critical ice 

accretions. 

In accordance with 14 CPR Part § 11.81, Cessna Aircraft Company wishes to submit the 

following information to request a grant of exemption using the guidance found in AC23 .1419-

2D, Paragraph 13a(l)(c). 

§11.81 (a) Your name and mailing address and if you wish, other contact information such as a 

fax number, telephone number, or e-mail address. 

Carlos Ayala 

Manager- Airworthiness 

Cessna Aircraft Company 

Department 390, 

One Cessna Boulevard P.O. Box 7704 

Wichita, Kansas 67277-7704 

Telephone: (316) 517-8575 

Fax: (316) 206-6336 

§11.81 (b) The Specific Section or sections of 14 CFRfrom which you seek an exemption; 

Cessna Aircraft Company seeks as exemption to 14 CPR §23.1419(a) with respect to the 61-knot 

stall speed requirement of §23.49(c). 

§11.81 (c) The extent of relief you seek and the reason you seek the relief; 

Specifically, Cessna Aircraft Company seeks an exemption to the following statement of 14 CPR 

§23.1419(a): 

"As used in this section, "Capable of operating safely", means that airplane 

performance, controllability, manoeuvrability and stability must not be less then that required in 

Part 23, subpart B. " 

Cessna Aircraft Company One Cessna Boulevard, P.O. Box 7704. Wichita, Kansas 67277-7704, W316/517-6000 
L390-12-1608 

27 July 2012 

Page 2 of4 

This exemption is only requested with respect to the 61-knot stall speed requirement of 14 CFR 

§23 .49( c) for the Model T240 CORY ALIS. 

While the non-contaminated stall speed of the T240 CORYALIS meets the 61-knot rule, the 

T240 CORYALIS with critical ice accretions will not. Thus, this exemption has been requested as 

described in the FAA guidance provided in AC23.1419-2D, Para 13a(l)(c). 

This exemption is only requested for aircraft units receiving an initial standard certificate of 

airworthiness subsequent to the type design certified by FAA project TD5550WI-A. Aircraft 

units manufactured prior to this project do not include the design requirements for FIKI 

operations and existing type design does not permit modifications to meet those design 

requirements. 

§11.81 (d) The reasons why granting your request would be in the public interest: that is how it 

would benefit the public as a whole; · 

The Model T240 CORY ALIS is primarily used for cross-country travel and has a high probability 

of encountering inclement weather- including ice conditions. Increasing the flight envelope of 

the T240 CORYALIS to include flight into known icing provides a significant increase in safety 

for operators ofT240 CORYALIS, especially those who inadvertently encounter icing 

conditions. The associated design features required to make FIKI operations possible add a 

significant level of redundancy and increased system capability over the existing design. Also, the 

flight testing required for this design change has fully proven out the capability of this system and 

shown that operational safety has increased. 

However, to maintain compliance with the 61-knot stall speed requirement of §23.49(c) as 

required by §23.1419(a), the useful load ofthe T240 CORYALIS would need to be reduced to 

account for the effects of airframe ice accumulation; i.e. aerodynamic contamination resulting in 

increased drag and loss of lift combined with the weight of airframe ice. This useful load 

reduction would have a considerable negative impact on the utility and safety of the T240 as both 

cabin load and reserve fuel would be potential areas of reduction. 

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

with the operational envelope expansion without negatively impacting aircraft utility and 

endurance. 

§11.81 (e) The reasons why granting the exemption would not adversely affect safety, or how the 

exemption would provide a level of safety at least equal to that provided by the rule from which 

you seek the exemption; 

The following compensating features as described in AC23.1419-2D will ensure the level of 

safety will not be adversely affected by this exemption. 

1. The airplane with no ice accretions meets the 61-knot stall speed requirements of §23.49(c). 

The T240 CORYALIS with no ice accretions stalls at less than 61-knot in the landing 

configuration at maximum gross weight as documented in the Pilot's Operating 

Handbook. 

2. The airplane with critical ice accretions as defined in the paragraphs 13.b of the AC23.1419-

2D complies with the stall requirements of §23.207. 
L390-12-1608 

27 July 2012 

Page 3 of4 

The T240 CORY ALIS maintains the required stall margin and does not cause nuisance 

warning as required by §23.207. This has been demonstrated by flight test and will be 

documented in the flight test reports that will be submitted to the FAA. 

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

The AFM supplement for FIKI equipped aircrafts will include 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 will be documented in the flight test 

reports that will be submitted to the FAA. 

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

controllable with normal piloting sills 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 skills as required by §23.141. This will be documented in the flight test 

reports that will be submitted to the FAA. 

5. The tire requirements of §23. 7 33 and brake requirements of §23. 7 35 are met with the higher 

stall and operating speeds. 

Cessna Aircraft Company has determined by analysis that the existing tyres and brake 

system will meet the requirements of §23.733 and §23.735 respectively. This will be 

documented in the certification reports that will be submitted to the FAA. 

6. The ground handling requirements of §23.231, §23.233 and §23.235 are met with the higher 

landing speeds. 

Cessna Aircraft Company conducted ground handling tests during the simulated ice 

shape flight tests and found no adverse handling characteristics. 

7. All other airplane system if 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. 

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

metal-to-meta/latching device. 

The T240 CORY ALIS utilises a seat restraint system that includes safety belts and 

shoulder harnesses with metal-to-metal latching devices for all four occupant seats. 

9. The airplane certification basis would have to include 23.1091 and 23.1093 at amendment 

level 23-51 to provide the latest regulations fir engine operation in icing conditions. 

The FAA project TD5550WI-A certification basis for the Cessna model T240 

CORYALIS will reflect the amendment level 23.51. 
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27 July 2012 

Page 4 of4 

10. The airplane certification basis would have to include 23.995 at amendment level23.29. 

The certification basis for the T240 COR VALIS was established including 23.995 at 

amendment level23.29. The existing compliance shown for this regulation shall not be 

affected by this type design change. 

§11.81 (f) A summary we can publish in the Federal Register stating; (1) The rule .from which you 

seek the exemption; and (2) A brief description of the nature of the exemption you seek; 

The FAA may publish this letter in its entirety. 

§11.81(g) Any additional information, views or arguments available to support your request; 

In addition to the compensating safety features discussed for 11.81 (e) above, Cessna Aircraft 

Company will be providing a training module specific to flight in icing conditions that will 

include training related to increased stall speeds associated with airframe ice accretions. This 

module will be similar to the flight in icing conditions currently in use for the Cessna Model 208 

Caravan. Cessna Aircraft Company has an excellent pilot training program that emphasizes the 

Operational Safety. This module will be made available to call Cessna CORV ALIS pilots, 

including those operating T240 CORV ALIS aircrafts equipped with FIKI operations. 

§11.81(h) lfyou want to exercise privileges of your exemption outside the United States, the 

reason why you need to do so; 

This petition for exemption is for type certification only. Thus, this item is not applicable to 

exemption described herein. 

In conclusion, Cessna Aircraft Company requests the FAA grant an exemption to 14CFR 

§23.1419(a) specific to the 61-knot stall speed requirement. This exemption would be in the 

public interest by providing increased safety in inclement weather without requiring a significant 

reduction in useful load. Further, the level of safety will be maintained by complying with the 

compensating features as described in AC233.1419-2D. 

Please feel free to contact me at (316)-51 7- , if you have any questions. 

Sincerely, 

Po De-- ~?-

Manager of Airworthiness 

Cessna Aircraft Company 

cc: Linda Dicken- Program Manager, Wichita ACO.