Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model BD-100-1A10 airplanes. This proposed AD was prompted by the discovery of a single-point failure within the left-hand and right-hand heater current monitor (HCM) units. This proposed AD would require installing a monitor circuit comprising relays external to the HCM units. This proposed AD would also require 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 proposing this AD to address the unsafe condition on these products.