…The Dynamic Rollover Was Likely Caused By The Front Seat Passenger Inadvertently Contacting The Cyclic Control While Turning To Speak With The Rear Seat Passenger Analysis: The pilot reported that while on a local flight he noticed a squall line approaching and elected to return to the private strip from which he had departed. During the approach, rain intensity increased, and the wind began gusting to about 15 knots. The pilot landed the helicopter, lowered the collective, and reduced power. While the main rotor was turning about 420 rpm, the helicopter suddenly rolled over onto its right side, resulting in substantial damage to the main rotor system and fuselage.