Learjet 60
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 125.2; Flight Crew Total 265000; Flight Crew Type 2799.6
Workload
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Weather
We were on arrival into ZZZ and on vectors with Approach Control. Prior to switching over to Approach Control ATC advised us that we could expect moderate turbulence; I believe from 9;000 to 12;000 feet; on descent. We were higher up on our descent when they notified us that we could expect the moderate turbulence in the lower altitude structure. We were switched over to approach control.  I remarked to approach that we were picking up moderate turbulence; again I believe we were at or above 6;000 feet to give them a heads up. We were given a left northerly turn to 010 degrees and a descent to 5;000 feet.  The Autopilot was engaged. It was very turbulent. We received an Alts Cap which is a normal indication on the FMA (Flight Mode Annunciator) that the autopilot is now armed to capture the selected altitude. We were getting bumped around pretty good by now; full continuous moderate turbulence. It was at that moment when the autopilot was capturing the altitude that the upset occurred. The aircraft was rocked to a 45 to 50 degree left bank and a sinking drop occurred similar to what you would receive in an airliner if you ever have hit an air pocket. This exceeded the limits of the autopilot and it kicked off. I took over manually to right the airplane and that is when we received what I would call a severe bump which led to the second upset that did the same thing; left bank to 45 to 50 degrees and a pitch downward.  I was already in the process of advancing power from the first upset but this time I went to full thrust; TOGA power if you will; to initiate the unusual attitude recovery.  I was aggressive in the recovery; put some G on the aircraft; airspeed bled down from 250 to about 180 or 190 at that moment which is still a safe flying airspeed in our type aircraft; well above stall.  I traded airspeed for altitude to expedite the recovery.  We recovered to altitude shortly after.This all happened so quickly.  Severe turbulence upset coupled with automation exceedance were contributing factors.  Lessons learned are significant. Turbulence is always a threat.Constance vigilance is always required.  Secondly we stress at our company to never fully rely on automation and that it will not always work in all situations.  We also stress that situations can happen to anyone regardless of experience. An Incident/Hazard Report has been filled out as part of our Safety Management System (SMS) program and submitted to the Director of Safety at our company. We train for upset situations every X months as part of our X month continuation qualification and training. I've flown many types of aircraft as well as fighter type aircraft and have never experienced a situation such as the one described above.
Lear 60 pilot reported that the aircraft encountered moderate to severe turbulence; resulting in two upsets and subsequent recovery.