Date: 202012
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Flight conditions: IMC
Weather elements / visibility: Rain; Thunderstorm; Turbulence; Windshear; 1
Light: Daylight
Aircraft: Bonanza 36
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: ADS-B (Automatic Dependent Surveillance - Broadcast)
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Sea
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Regained Aircraft Control
Contributing factors: Aircraft; Weather
Primary problem: Weather

Narrative: I was flying on an IFR flight plan at assigned altitude of 4000'. After seeing a cell on FIS-B radar (Flight Information System-Broadcast); I requested from ATC if there were any PIREPS for the weather. I then requested a deviation for weather depicted by FIS-B. I was granted the requested weather deviation and was flying outside of the weather depicted by FIS-B several miles in IMC conditions. Apparently; I flew into an embedded thunderstorm cell with both severe turbulence and violent downdrafts and updrafts which was not depicted by FIS-B weather with a 4 minute time stamp.I noticed the IAS had climbed dangerously high into the yellow arc while on autopilot (AP) maintaining an altitude of 4;000'. I reduced power to idle in an effort to maintain a safe indicated airspeed. While the AP was engaged and power reduced the IAS did not reduce sufficiently to the maneuvering speed but was rapidly climbing. I disconnected the AP and pulled the yoke back to reduce IAS. I then encountered severe turbulence and downdrafts forcing the aircraft to lose approximately 500 feet. In an attempt to stabilize the aircraft; I attempted to various throttle settings in an attempt to maintain altitude and heading with little success in controlling altitude or heading.The entire event lasted approximately 2 minutes with several calls from ATC offering assistance. During those calls I requested ATC standby until I was able to regain control of the aircraftThis was an isolated cell whose location was not accurately depicted by FIS-B weather radar returns. In regards to corrective actions on my part as pilot; I'd say to not trust FIS-B time stamps nor the weather depictions as being reasonably accurate. Further I'd extend my safety margin around weather depicted on FIS-B to a greater margin.The flight terminated without incident with my cancelling my IFR flight plan once out of IMC conditions and safely landing at the destination airport.




Synopsis: BE36 pilot reported difficulty controlling altitude and heading after entering a thunderstorm that was not depicted on Flight Information System-Broadcast (FIS-B).