Flight Crew Multiengine
Flight Crew Last 90 Days 150; Flight Crew Total 2100; Flight Crew Type 1000
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Regained Aircraft Control
Weather
While on arrival into Nashville; we were being vectored by Approach.  We were just assigned vectors outside of the arrival.  We were notified by the controlling agency that we could expect moderate turbulence between 9;000 and 12;000 feet in the descent; which we did encounter.  Upon reaching 5;000 feet; we were still encountering moderate turbulence.  As we accepted our vector to heading 010; we encountered a pocket of severe turbulence which sent the airplane into an upsetting unusual attitude.  My Captain immediately recognized the issue; as the autopilot kicked itself off; he initiated the proper recovery procedure.  As that happened; we encountered a second pocket of severe turbulence which further upset the aircraft attitude and resulted in additional altitude loss.  My Captain went full thrust and maximum nose up attitude to recover.  We experienced moderate turbulence all the way to the ground that day; but were able to land safely.
Corporate First Officer reported a severe turbulence encounter during approach to BNA airport resulting in an altitude excursion and momentary loss of aircraft control.