Airworthiness Directives; Twin Commander Aircraft Corporation 680, 681, 690, and 695 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Twin Commander Aircraft Corporation (Twin Commander) 680, 681, 690, and 695 series airplanes. This action requires installing a placard warning the pilot to observe turbulent air penetration speeds. Two accidents involving Model 690 airplanes where the affected airplanes encountered turbulence while descending at high speeds prompted this action. The actions specified by this AD are intended to prevent structural damage to the airplane caused by excessive turbulence, which could result in loss of control of the airplane.