Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Cessna Model 560 airplanes. The existing AD currently requires installing new minimum airspeed placards to notify the flightcrew of the proper airspeeds for operating in both normal and icing conditions. The existing AD also requires revising the airplane flight manual to provide limitations and procedures for operating in icing conditions, for operating with anti-ice systems selected "on'' independent of icing conditions, and for recognizing and recovering from inadvertent stall. The existing AD also provides an optional terminating action for the placard installation. This proposed AD would require the previously optional terminating action. This proposed AD results from an evaluation of in-service airplanes following an accident. The evaluation indicated that some airplanes might have an improperly adjusted stall warning system. We are proposing this AD to prevent an inadvertent stall due to the inadequate stall warning margin provided by an improperly adjusted stall warning system, which could result in loss of controllability of the airplane.