Airworthiness Directives; Bombardier Model CL-600-2C10 (Regional Jet Series 700 & 701) Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Bombardier Model CL-600-2C10 (Regional Jet Series 700 & 701) series airplanes. This action requires revising the airplane flight manual (AFM) to advise the flightcrew to limit use of the auxiliary power unit (APU) to ground operation only, except for those in-flight emergencies described in the AFM when use of the APU is specified. This action also provides for optional terminating action for the requirements of this AD. This action is necessary to prevent fuel from being sprayed throughout the APU compartment and drawn out of the APU exhaust duct due to a cracked APU fuel nozzle, which could result in a fire or explosion in the APU compartment during flight. This action is intended to address the identified unsafe condition.