Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
There have been several occurrences of the air driven generator (ADG) failure to power essential buses during functional tests of the ADG. It was found that the low threshold setting of the circuit protection on the ADG generator control unit (GCU) can prevent the supply of power from the ADG to the essential buses. In the event of an emergency, loss of power to the essential buses can prevent continued safe flight.
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The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.