UPS B763 over Greenland on Dec 18th 2013, 7 minutes of severe turbulence and control difficulties

A UPS Boeing 767-300, registration N322UP performing freight flight 5X-238 from London Stansted,EN (UK) to Louisville,KY (USA), was enroute at FL310 northeast of Narsasuaq (Greenland) when the aircraft encountered severe turbulence, the crew had difficulty to maintain assigned altitude, speed and directional control, the autopilot and autothrottles disconnected repeatedly until the aircraft, the aircraft deviated from assigned altitude to FL304 and FL341 encountering smooth air at and above FL340 about 7 minutes after the onset of turbulence. The flight was cleared to maintain FL340 and continued to Louisville for a safe landing.

Canada's TSB reported that after landing the aircraft underwent inspections in compliance with the Boeing turbulence inspection requirements.