Date: 201908
Local time of day: 0601-1200
Location: ZLA.ARTCC, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Challenger 605
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZLA
ATC / advisory: Center ZLA
Second aircraft: B777 Undifferentiated or Other Model
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control
Contributing factors: Environment - Non Weather Related; Procedure
Primary problem: Environment - Non Weather Related

Narrative: En route cruise was at FL310 with the autopilot ON in very smooth air and clear skies.  Los Angeles Center had issued our clearance to descend VIA the IRNMN2 arrival into LAX and we were about 20 miles prior to the Top of Descent.  At the time; we saw traffic on TCAS ahead and below us but did not know the type; route or other details of the preceding traffic.  Unbeknownst to us; ATC had also descended a Heavy 777 approximately 10 miles ahead of us from FL370 to also descend VIA the IRNMN2 arrival.   [A few minutes later] our aircraft encountered a series of several sharp jolts of turbulence followed immediately by an uncommanded high rate roll to the right to a bank angle of approximately 75 degrees; immediately followed by a high rate roll to the left to approximately 45 degrees bank angle.  My hands went to the yoke nearly immediately after the initial sharp jolt and I countered the roll with full left aileron.  The autopilot remained engaged during the first uncommanded roll and I disconnected the autopilot and hand flew the aircraft at some point during the uncommanded roll to the left. At this point we also received a CAS message of 'R ENG OIL PRESS' along with the aural warning of 'Engine Oil Pressure'.  I glanced at the engine instruments and noted no discrepancies and the warnings were extinguished almost immediately. The entire evolution likely lasted less than about four seconds.  The Pilot Monitoring contacted ATC and notified them of our encounter with severe wake turbulence and asked ATC of the preceding aircraft type.  I was still hand flying and re-engaged the autopilot in heading mode and altitude hold steering the aircraft to the right of course.  I believe that the maximum altitude loss was less than 120 feet.  The Pilot Monitoring asked for a 2nm offset to the right of course which ATC granted.  With the aircraft in full control and in smooth air I asked the Pilot Monitoring to go to the cabin to check on our passenger and the condition of the cabin.  Our passenger; though somewhat alarmed; was unhurt with his seatbelt on.  A number items in the galley and forward coat closet had been displaced and were on the galley floor.  Numerous items in the baggage bay had also been displaced from their shelves and on the floor.  There appeared to be no other damage.  ATC asked when we could rejoin the arrival but we requested to continue our offset until we were entirely clear of the potential for further wake encounter.  The remainder of the flight proceeded without issue.Over the past four years; it seems that we have experienced a greater number of wake turbulence encounters with this one being the most severe.  It would seem to me that one potential cause of this is the increased lateral navigation accuracy in combination with the advent of 'Descend VIA' clearances and the very accurate vertical paths that are maintained.  Further; there seems to be either a nonchalance or obliviousness on the part of ATC regarding the crossing of a Heavy aircraft ahead and above smaller aircraft without passing on any information that could be of concern to the safety of flight of following smaller aircraft.  Going forward we will be more vigilant and determine aircraft type for ANY aircraft ahead and above our location and not assume that ATC has our best interest in mind.Additionally; the majority of our training in regard to wake turbulence has been targeted at the hazards in the terminal areas of takeoff and landing but in our experience; the greater number of our encounters have been in the en route and arrival phases of flight and no training that I am aware of has focused on this issue.   Post flight inspection did not reveal any defects. A squawk was submitted for severe wake turbulence encounter.




Synopsis: CL-605 Captain reported a 'severe' wake turbulence encounter at FL310 in trail of a B777 on arrival into LAX.