Airworthiness Directives; Bombardier, Inc., Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Bombardier, Inc., Model BD-100-1A10 airplanes. This AD was prompted by the discovery of a single-point failure within the left- hand and right-hand heater current monitor (HCM) units. This AD requires installing a monitor circuit comprising relays external to the HCM units. This AD also requires revising the normal and non-normal procedure sections of the existing airplane flight manual (AFM) to add new procedures associated with revised crew alerting system (CAS) messages. The FAA is issuing this AD to address the unsafe condition on these products.