
[Federal Register Volume 77, Number 141 (Monday, July 23, 2012)]
[Rules and Regulations]
[Pages 42949-42952]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-17864]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2012-0485; Special Conditions No. 23-258-SC]


Special Conditions: Tamarack Aerospace Group, Cirrus Model SR22; 
Active Technology Load Alleviation System (ATLAS)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for the Tamarack Aerospace 
Group's modification to the Cirrus SR22 airplane. This airplane as 
modified by Tamarack will have a novel or unusual design feature(s) 
associated with Tamarack Aerospace Group's modification. The design 
change will install winglets and an Active Technology Load Alleviation 
system (ATLAS). The addition of the ATLAS mitigates the negative 
effects of the winglets by effectively aerodynamically turning off the 
winglet under limit gust and maneuver loads. This is accomplished by 
measuring the aircraft loading and moving a small aileron-like device 
called a Tamarack Active Control Surface (TACS). The TACS movement 
reduces lift at the tip of the wing, resulting in the wing center of 
pressure moving inboard, thus reducing bending stresses along the wing 
span. 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: Effective Date: July 13, 2013.

FOR FURTHER INFORMATION CONTACT: For sections 23.301 through 23.629 
(structural requirements), contact Mr. Mike Reyer, telephone (816) 329-
4131. For sections 23.672 through 23.701 (control system requirements), 
contact Mr. Ross Schaller, telephone (816) 329-4162. The address and 
facsimile for both Mr. Reyer and Mr. Schaller is: Small Airplane 
Directorate, Aircraft Certification Service, 901 Locust, Kansas City, 
Missouri 64106; facsimile (816) 329-4090.

SUPPLEMENTARY INFORMATION:

Background

    On February 15, 2011, Tamarack Aerospace Group applied for a 
supplemental type certificate for installation of winglets and an 
Active Technology Load Alleviation System (ATLAS) on the Cirrus Model 
SR22 (serial numbers 0002-2333, 2335-2419, and 2421-2437). The Cirrus 
Model SR22 is a certified, single reciprocating engine, four-passenger, 
composite airplane.
    The installation of winglets, as proposed by Tamarack, increases 
aerodynamic efficiency. However, the winglets by themselves also 
increase wing static loads and the wing fatigue stress ratio, which 
under limit gust and maneuver loads factors may exceed the certificated 
wing design limits. The addition of ATLAS mitigates the negative 
effects of the winglets by effectively aerodynamically turning off the 
winglet at elevated gust and maneuver loads factors.
    The ATLAS functions as a load-relief system. This is accomplished 
by measuring aircraft loading via an accelerometer, and by moving a 
small aileron-like device called a Tamarack Active Control Surface 
(TACS) that reduces lift at the tip of the wing. Because the ATLAS 
compensates for the increased wing root bending at elevated load 
factors, the overall effect of this modification is that the winglet 
can be added to the Cirrus wing without the traditionally required 
reinforcement of the existing structure. This is the first application 
of an active loads alleviation system on a part 23 aircraft and the 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature.

[[Page 42950]]

Type Certification Basis

    Under the provisions of Sec.  21.101, Tamarack Aerospace Group must 
show that the Cirrus Model SR22, as changed, continues to meet the 
applicable provisions of the regulations incorporated by reference in 
Type Certificate Data Sheet A00009CH or the applicable regulations in 
effect on the date of application for the change. The regulations 
incorporated by reference in the type certificate are commonly referred 
to as the ``original type certification basis.'' The regulations 
incorporated by reference in Type Certificate Data Sheet A00009CH 
(Serial Numbers (S/Ns) 0002 through 2333, 2335 through 2419, and 2421 
through 2437) are as follows:

14 CFR part 23 of the Federal Aviation Regulations, effective February 
1, 1965, as amended by 23-1 through 23-53, except as follows:
    14 CFR 23.301 through Amendment 42
    14 CFR 23.855, 23.1326, 23.1359 not applicable
    14 CFR part 36, dated December 1, 1969, as amended by 36-1 through 
36-22
Except for:
    Increase in amendment level from the cirrus Model SR22 
certification basis for Regulation 14 CFR 23.301 through amendment 23-
42 to: 14 CFR 23.301 through Amendment 23-48.
Addition of regulation 14 CFR 23.1306 through Amendment 23-61.
Addition of regulation 14 CFR 23.1308 through Amendment 23-57.
    Change in Cirrus Model SR22 certification basis for regulation 14 
CFR 23.1359 through Amendment 23-49 from: Not Applicable to: Applicable
Equivalent Level of Safety (ELOS) Findings
    ACE-96-6 for 14 CFR Section 23.221 (Spinning); refer to FAA 
Memorandum, dated June 10, 1998, for Models SR20, SR22.
    ACE-00-09 for 14 CFR 23.1143(g) (Engine Controls) and 23.1147(b) 
(Mixture Controls) Refer to FAA Memorandum, dated September 11, 2000, 
for Model SR22.
    ACE-01-01 for 14 CFR 23.1143(g) (Engine Controls) and 23.1147(b) 
(Mixture Controls); Refer to FAA Memorandum, dated February 14, 2001, 
for Model SR20.
Special Conditions
    23-ACE-88 for ballistic parachute for Models SR20, SR22.
    23-134-SC for protection of systems for High Intensity Radiated 
Fields continued: (HIRF), for Models SR20, SR22.
23-163-SC for inflatable restraint system. Addition to the 
certification basis Model SR20 effective S/N 1541 and subsequent; Model 
SR22 S/N 1500, 1520 and subsequent.
    In addition, if the regulations incorporated by reference do not 
provide adequate standards regarding the change, the applicant must 
comply with certain regulations in effect on the date of application 
for the change. The FAA has determined that the Cirrus SR22 complies 
with the following sections of 14 CFR part 23, as amended by Amendments 
23-1 through 23-61 for the areas affected by the change.
    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 SR22 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 SR22 must comply with the fuel vent and exhaust 
emission requirements of 14 CFR part 35 and the noise certification 
requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in Sec.  11.19, in 
accordance with Sec.  11.38 and they become part of the type 
certification basis under Sec.  21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should the applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design feature, 
the special conditions would also apply to the other model under Sec.  
21.101.

Novel or Unusual Design Features

    The SR22 will incorporate the following novel or unusual design 
features:
    Winglets with an Active Technology Load Alleviation System (ATLAS) 
that incorporates a small aileron-like device called a Tamarack Active 
Control Surface (TACS).

Discussion

    Tamarack has applied for a Supplemental Type Certificate to install 
a winglet and ATLAS. The ATLAS is not a primary flight control system, 
a trim device, or a wing flap. However, there is definite applicability 
to ATLAS for several regulations under part 23, Subpart D--Control 
Systems, which might otherwise be considered ``Not Applicable'' under a 
strict interpretation of the regulations. Other conditions may be 
developed, as needed, based on further FAA review and discussions with 
the manufacturer.
    Special conditions are also necessary for the effect of ATLAS on 
structural performance. These special conditions are intended to 
provide an equivalent level of safety for ATLAS as intended by part 23, 
Subpart C--Structure, and portions of part 23, Subpart D--Design and 
Construction.

Discussion of Comments

    Notice of proposed special conditions No. 23-12-01-SC for the 
Cirrus SR22 airplanes was published on May 15, 2012 (77 FR 28530). No 
comments were received and the special conditions are adopted as 
proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
SR22 (S/NS 0002 thru 2333, 2335 thru 2419, and 2421 thru 2437). Should 
Tamarack Aerospace Group apply at a later date for a supplemental type 
certificate to modify any other model included on Type Certificate Data 
Sheet A00009CH to incorporate the same novel or unusual design feature, 
the special conditions would apply to that model as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register; however, as the certification date for the Tamarack 
modified Cirrus SR22 is imminent, the FAA finds that good cause exists 
to make these special conditions effective upon issuance.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplane. 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.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

0
The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

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 Cirrus Model SR22 airplanes (S/Ns 0002 
through 2333, 2335 through 2419, and 2421 through 2437) modified by 
Tamarack Aerospace Group.

[[Page 42951]]

1. Active Load Alleviation Systems--Structural Requirements

    (A) The following special conditions apply to airplanes equipped 
with load alleviation systems that either directly, or as a result of 
failure or malfunction, affect structural performance. These special 
conditions address the direct structural consequences of the system 
responses and performances and cannot be considered in isolation but 
should be included in the overall safety evaluation of the airplane. 
Any statistical or probability terms used in the following special 
conditions apply to the structural requirements only and do not 
replace, remove, or supersede other requirements, including those in 
part 23, subpart E. These criteria are only applicable to structure 
whose failure could prevent continued safe flight and landing.
    (B) In addition to the requirements in 14 CFR part 23, Sec.  23.301 
Loads, comply with the following:
SC 23.301 Loads, Probability of Failure of Load Alleviation System
    (a) Failures of the load alleviation system, including the 
annunciation system, must be immediately annunciated to the pilot or 
annunciated prior to the next flight. Failure of the load alleviation 
system, including the annunciation system, must be no greater than 1 x 
10-5 per flight hour.
    (b) If failure of the load alleviation system, including the 
annunciation system, is greater than 1 x 10-8 per flight 
hour, an independent system functional test must be accomplished at a 
periodic interval to limit time exposure to an undetected failed 
system. The time interval for the system functional test must be 
selected so that the product of the time interval in hours and the 
failure of the load alleviation system, including the annunciation 
system, is no greater than 1 x 10-5 per hour.
    (c) Failures of the load alleviation system, including the 
annunciation system, must be reported to the FAA in a manner acceptable 
to the Administrator.
    (C) In place of the requirements in 14 CFR part 23, Sec.  23.303 
Factor of Safety, comply with the following:
SC 23.303 Factor of Safety, Load Alleviation Systems
    The airplane must be able to withstand the limit and ultimate loads 
resulting from the following scenarios:
    (a) The loads resulting from 14 CFR part 23, Sec. Sec.  23.321 
through 23.537, as applicable, corresponding to a fully operative load 
alleviation system. A factor of safety of 1.5 must be applied to 
determine ultimate loads.
    (b) If an independent system functional test is required by SC 
23.301(b), the loads resulting from 14 CFR part 23, Sec. Sec.  23.321 
through 23.537, as applicable, corresponding to the system in the 
failed state without additional flight limitations or reconfiguration 
of the airplane. A factor of safety of 1.0 must be applied to determine 
ultimate loads.
    (c) The loads corresponding to the time of occurrence of load 
alleviation system failure and immediately after the failure. These 
loads must be determined at any speed up to VNE, starting 
from 1g level flight conditions, and considering realistic scenarios, 
including pilot corrective actions. A factor of safety of 1.5 must be 
applied to determine ultimate loads.
    (d) For airplanes equipped with ``before the next flight'' failure 
annunciation systems, the loads resulting from 14 CFR part 23, 
Sec. Sec.  23.321 through 23.537, as applicable, corresponding to the 
system in the failed state without additional flight limitations or 
reconfiguration of the airplane. A factor of safety of 1.25 must be 
applied to determine ultimate loads.
    (e) For airplanes equipped with ``immediate'' failure annunciation 
systems, the loads resulting from 14 CFR part 23, Sec. Sec.  23.321 
through 23.537, as applicable, corresponding to the system in the 
failed state with additional flight limitations or reconfiguration of 
the airplane. A factor of safety of 1.0 must be applied to determine 
ultimate loads.
    (D) In addition to the requirements in 14 CFR part 23, Sec. Sec.  
23.571 through 23.574, comply with the following:
SC 23.571 Through SC 23.574 Fatigue and Damage Tolerance
    If any system failure would have a significant effect on the 
fatigue or damage evaluations required in Sec. Sec.  23.571 through 
23.574, then these effects must be taken into account. If an 
independent system functional test is required by SC 23.301(b), the 
effect on fatigue and damage evaluations resulting from the selected 
inspection interval must be taken into account.
    (E) In addition to the requirements in 14 CFR part 23, Sec.  23.629 
Flutter, comply with the following:
SC 23.629 Flutter
    (a) With the load alleviation system fully operative, compliance to 
14 CFR part 23, Sec.  23.629 must be shown. Compliance with Sec.  
23.629(f) must include the ATLAS control system and control surface.
    (b) At the time of occurrence of load alleviation system failure 
and immediately after the failure, compliance with 14 CFR part 23, 
Sec.  23.629(a) and (e) must be shown up to VD/MD 
without consideration of additional operating limitations or 
reconfiguration of the airplane.
    (c) For airplanes equipped with ``before the next flight'' failure 
annunciation systems and the load alleviation system in the failed 
state, compliance to 14 CFR part 23, Sec.  23.629 Flutter, paragraphs 
(a) and (e), must be shown up to VD/MD without 
consideration of additional operating limitations or reconfiguration of 
the airplane.
    (d) For airplanes equipped with ``immediate'' failure annunciation 
systems and the load alleviation system in the failed state, compliance 
to 14 CFR part 23, Sec.  23.629 Flutter, paragraphs (a) and (e), must 
be shown with consideration of additional operating limitations or 
reconfiguration of the airplane at speeds up to VD = 1.4 x 
maximum speed limitation selected by the applicant.

2. Active Load Alleviation Systems--Control System Requirements.

    (A) In place of 14 CFR part 23, Sec.  23.672 Stability augmentation 
and automatic and power-operated systems requirement, comply with the 
following:
SC 23.672 Load Alleviation Systems
    The load alleviation system must comply with the following:
    (a) A warning, which is clearly distinguishable to the pilot under 
expected flight conditions without requiring the pilot's attention, 
must be provided for any failure in the load alleviation system or in 
any other automatic system that could result in an unsafe condition if 
the pilot was not aware of the failure. Warning systems must not 
activate the control system.
    (b) The design of the load alleviation system or of any other 
automatic system must permit initial counteraction of failures without 
requiring exceptional pilot skill or strength, by either the 
deactivation of the system or a failed portion thereof, or by 
overriding the failure by movement of the flight controls in the normal 
sense.
    (c) It must be shown that, while the system is active or after any 
single failure of the load alleviation system--
    (1) The airplane is safely controllable when the failure or 
malfunction occurs at any speed or altitude within the approved 
operating limitations that is critical for the type of failure being 
considered;

[[Page 42952]]

    (2) The controllability and maneuverability requirements of this 
part are met within a practical operational flight envelope (for 
example, speed, altitude, normal acceleration, and airplane 
configuration) that is described in the Airplane Flight Manual (AFM); 
and
    (3) The trim, stability, and stall characteristics are not impaired 
below a level needed to permit continued safe flight and landing.
    (B) In place of 14 CFR part 23, Sec.  23.677 Trim systems 
requirement, comply with the following:
SC 23.677 Load Alleviation Active Control Surface
    (a) Proper precautions must be taken to prevent inadvertent, 
improper, or abrupt Tamarack Active Control Surface (TACS) operation.
    (b) The load alleviation system must be designed so that, when any 
one connecting or transmitting element in the primary flight control 
system fails, adequate longitudinal control for safe flight and landing 
is available.
    (c) The load alleviation system must be irreversible unless the 
TACS is properly balanced and has no unsafe flutter characteristics. 
The system must have adequate rigidity and reliability in the portion 
of the system from the tab to the attachment of the irreversible unit 
to the airplane structure.
    (d) It must be demonstrated that the airplane is safely 
controllable and that the pilot can perform all maneuvers and 
operations necessary to effect a safe landing following any probable 
powered system runaway that reasonably might be expected in service, 
allowing for appropriate time delay after pilot recognition of the 
system runaway. The demonstration must be conducted at critical 
airplane weights and center of gravity positions.
    (C) In place of 14 CFR part 23, Sec.  23.683 Operation tests 
requirement, comply with the following:
SC 23.683 Operation tests
    (a) It must be shown by operation tests that, when the load 
alleviation system is active and operational and loaded as prescribed 
in paragraph (b) of this section, the system is free from--
    (1) Jamming;
    (2) Excessive friction; and
    (3) Excessive deflection.
    (b) The prescribed test loads are, for the entire system, loads 
corresponding to the limit airloads on the appropriate surface.
    (D) In place of 14 CFR part 23, Sec.  23.685 Control system details 
requirement, comply with the following:
SC 23.685 Control System Details
    (a) Each detail of the Tamarack Active Control Surface (TACS) must 
be designed and installed to prevent jamming, chafing, and interference 
from cargo, passengers, loose objects, or the freezing of moisture.
    (b) There must be means in the cockpit to prevent the entry of 
foreign objects into places where they would jam any one connecting or 
transmitting element of the system.
    (c) Each element of the load alleviation system must have design 
features, or must be distinctively and permanently marked, to minimize 
the possibility of incorrect assembly that could result in 
malfunctioning of the control system.
    (E) In place of 14 CFR part 23, Sec.  23.697 Wing flap controls 
requirement, comply with the following:
SC 23.697 Load Alleviation System Controls
    (a) The Tamarack Active Control Surface (TACS) must be designed so 
that, when the surface has been placed in any position, it will not 
move from that position unless the control is adjusted or is moved by 
the automatic operation of a load alleviation system.
    (b) The rate of movement of the TACS in response to the automatic 
device must give satisfactory flight and performance characteristics 
under steady or changing conditions of airspeed, engine power, and 
attitude.
    (F) In place of 14 CFR part 23, Sec.  23.701 Flap interconnection 
requirement, comply with the following:
SC 23.701 Load Alleviation System Interconnection
    (a) The load alleviation system and related movable surfaces as a 
system must--
    (1) Be synchronized by a mechanical interconnection between the 
movable surfaces; or by an approved equivalent means; or
    (2) Be designed so that the occurrence of any failure of the system 
that would result in an unsafe flight characteristic of the airplane is 
extremely improbable; or
    (b) The airplane must be shown to have safe flight characteristics 
with any combination of extreme positions of individual movable 
surfaces.

    Issued in Kansas City, Missouri, on July 13, 2013.
Earl Lawrence,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2012-17864 Filed 7-20-12; 8:45 am]
BILLING CODE 4910-13-P


