Bombardier CL-600 – Air Driven Generator Deployed

C-GGJA, a Bombardier CL-600-2B19 CRJ200 aircraft operated by Jazz Aviation LP, was conducting flight JZA8031 from Philadelphia Intl, PA (KPHL) to Montreal/Pierre Elliott Trudeau Intl, QC (CYUL) with 4 crew members and 33 passengers on board. Shortly after the departure from KPHL, the flight crew noticed that the Air Driven Generator (ADG) had deployed. The flight crew requested to return to KPHL and declared a PAN PAN. The aircraft landed back in KPHL without further incident.