Incident Overview
A pilot flying a Beech C90-1 reported encountering severe turbulence during a climb, causing the aircraft to be thrown inverted and enter a nose-down dive. The event occurred while the airplane was under autopilot control, level at 17,000 feet between cloud layers. The pilot observed buildups ahead and requested a slight turn and a climb to flight level 190 from air traffic control, which was approved.
Weather and Radar
Prior to the encounter, the aircraft's weather radar and stormscope showed no indications of severe weather. The pilot entered clouds during a right climbing turn, and almost immediately, the airplane experienced severe turbulence.
Loss of Control and Recovery
The turbulence threw the airplane inverted into a nose-down attitude. As airspeed increased, the pilot reduced throttles to idle and pushed propeller levers full forward. The pilot then rolled the aircraft upright and applied extreme back pressure on the yoke to recover from the dive. The upset began at approximately 17,500 feet, and recovery was completed at 10,500 feet.
Post-Flight Inspection
After the flight, the pilot climbed the airplane to FL190 and completed the remainder of the trip without further issues. However, a subsequent preflight inspection revealed wrinkling in the wing sheet metal, indicating structural stress from the event.
Summary
No injuries or other damage were reported. The incident highlights the potential for unexpected severe turbulence even when onboard weather detection systems show no threats.