Airworthiness Directives; Bombardier, Inc., Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Bombardier, Inc., Model BD-100-1A10 airplanes. This AD was prompted by a report of multiple in-service events where, following a STAB TRIM FAULT advisory message and auto-pilot disconnect, flightcrew commands for a nose-up trim resulted in nose-down trim movement of the horizontal stabilizer instead. This AD requires revising the existing airplane flight manual (AFM) to provide the flightcrew with instructions for an expanded pre-flight check of the pitch trim, trim malfunction procedures, and revised "AP STAB TRIM FAIL" caution and "STAB TRIM FAULT" advisory procedures. The FAA is issuing this AD to address the unsafe condition on these products.