PC-12
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 79; Flight Crew Total 10765; Flight Crew Type 3960
Workload
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Became Reoriented; Flight Crew Regained Aircraft Control
Weather
The flight was Part 91 in a Pilatus PC-12 flying to ZZZ.The flight proceeded normally. The weather at my destination ZZZ was Marginal VFR with broken clouds at 2;100 feet and broken at 4;000 feet and 10 miles visibility. There were showers reported in the vicinity. Approach was vectoring me for an ILS. The closer I got to the destination airport and as we descended; I encountered increasing IMC. The radar showed green with some yellow. There was not a concern for wide areas of heavy rain that could not be circumnavigated. As we were descending to an assigned altitude of 9;000 feet; I encountered moderate turbulence. As I was reaching to disconnect the autopilot; we encountered a severe down draft that took me past my altitude and put the plane in a 45 degree roll to the right. The attitude and turbulence disconnected the autopilot before I had a chance to. My first concern was to regain a wings level attitude while slowing the aircraft and then stop the descent. By the time the plane was under control and the turbulence subsided to light/moderate; the altitude was estimated to be arrested around 7;700 MSL.At that point; Approach asked to what altitude I was descending to. I explained what I encountered. He told me to 'just maintain 7;000 feet'.The rest of the flight to the ILS and eventually a VFR landing was uneventful.
PC-12 pilot reported on initial approach in IMC conditions and encountered severe turbulence and a downdraft the disconnected the autopilot. The pilot recovered and made an uneventful landing.