Date: 201706
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: Turbulence
Light: Daylight
Aircraft: Learjet 70
Operator: Air Taxi
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Rudder Control System
Component problem: Malfunctioning
Reporter organization: Air Taxi
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Time Pressure; Situational Awareness; Workload; Distraction
Second reporter function: Captain; Pilot Not Flying
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation - Track / Heading All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Became Reoriented; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Weather

Narrative: I was flying pilot and Captain was acting PIC. We used NEXRAD and Aircraft Radar to discover that on the other side of the state was a system of storms. This caused us to make a northern course change approved by ATC.We saw out our windscreen a cloud that did not appear on any of our weather detection screens; we determined that we would ask for a 30 degree deviation around the northern side of this cloud; which was approved; we were about 20-30 miles in front of this cloud.Once the turn was completed; our airspeed went from about .77 to .81 as the aircraft began to shake. I brought the thrust levers to idle as the airspeed continued to increase. I transferred controls to the PIC; as the aircraft began to descend uncontrollably and at its worst the airspeed increased to about .83/4 and descent rate was roughly 7;000 ft/min. Immediately after transferring controls; I informed Center that we had encountered extreme clear air turbulence and was in an uncontrolled descent. During this time we also encountered an uncontrolled yaw/turn movement as well. ATC responded asking if we would be able to level at 37;000 and I told them negative and would level as soon as we were able; which ended up being 33;000 feet.Once the aircraft was under control we contacted maintenance to better understand if we should continue and made the decision to do so. Over Wisconsin we began to have small system failures one after the other including Rudder boost; yaw dampener; and autopilot; we ran the QRH for all the affiliated CAS messages and made the decision to continue with the flight.The flight was completed upon our landing in our filed destination.We did everything we could with the time we had to correct all deviations within the aircraft including course; altitude; and airspeed. We were in VMC conditions and advised ATC of our actions and reasons why. There was no way we could have prevented this situation with the tools we had at our disposal.


Second narrative: Cruising at FL410. Made a left turn to deviate around some weather that was approximately 50 miles ahead. In the turn we encountered extreme clear air turbulence. I disconnected the autopilot because it was not able to handle the turbulence. We were not able to hold altitude and ended up descending to FL330. We let ATC know of the deviation asap; and that was when we were passing through FL400. No aircraft were in the area at the time.


Synopsis: A Learjet 70 flight crew described the entry and recovery from an extreme clear air turbulence encounter which damaged the aircraft while losing 7;000 FT and exceeding Mach .83.