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

This action amends special conditions No. 23-258-SC, issued on July 13, 2012, for the Tamarack Aerospace Group's modification to the Cirrus Model SR22 airplane. This amendment clarifies the intent of two requirements: The requirement for reporting of load alleviation system failures (see paragraph (c) under Loads, Probability of Failure of Load Alleviation System) and the requirement for consideration of limit loads with an unannunciated load alleviation system failure (see paragraph (b) under Factor of Safety, Load Alleviation Systems). 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 final 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. Additionally, this amendment corrects the issue date of special condition No. 23-258-SC to July 13, 2012.