Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all EMBRAER Model EMB-120 series airplanes. This proposal would require revising the Airplane Flight Manual (AFM) to include requirements for activation of the ice protection systems, and to add information regarding operation in icing conditions. This proposal also would require installing an ice detector system and revising the AFM to include procedures for testing system integrity. This proposal is prompted by reports indicating that flightcrews experienced difficulties controlling the airplane during (or following) flight in normal icing conditions, when the ice protection system either was not activated when ice began to accumulate on the airplane, or the ice protection system was never activated. These difficulties may have occurred because the flightcrews did not recognize that a significant enough amount of ice had formed on the airplane to require activation of the deicing equipment. The actions specified by the proposed AD are intended to ensure that the flightcrew is able to recognize the formation of significant ice accretion and take appropriate action; such formation of ice could result in reduced controllability of the airplane in normal icing conditions.