FLC OF AN ACR SMT TWIN ENG TURBO PROP ACFT MOMENTARILY LOST CTL OF THE ACFT ON TKOF DUE TO THE AILERON TRIM TAB SET ALL THE WAY TO THE L.

Narrative

RIGHT AFTER V1 CALL ACFT MADE SHARP ROLL TO THE L; INITIAL THOUGHT WAS AN ENG FAILURE. AFTER CHKING GAUGES AND FINDING NOTHING WRONG; I LOOKED DOWN TO MY L AND NOTICED AILERON TRIM WAS SHOWING A FULL DEFLECTION TO THE L. THE CAPT ALSO NOTICED THE SAME. I HELPED WITH THE CTLS TO LEVEL ACFT AFTER WHICH THE CAPT GAVE OVER CTLS TO ME WHILE HE RAN THE TRIM BACK AND PULLED THE CIRCUIT BREAKER. THE RWY IS CUT OUT AMONGST THE TREES SO AFTER GETTING EVERYTHING SITUATED WE CLRED THE TREES BY ABOUT 100-200 FT. THE FLT CONTINUED WITHOUT FURTHER INCIDENT. INITIAL ASSESSMENT WAS A RUNAWAY TRIM TAB; BUT IT PROBABLY WOULD NOT HAVE RETURNED TO CENTER. THE NEXT DAY I REMEMBERED THAT A PAX POKED INTO THE COCKPIT WHILE WE WERE AT THE HOLD LINE INQUIRING ABOUT HER HEAD SEAT. TRIM TAB IS LOCATED RIGHT AT THE ENTRANCE TO COCKPIT; PAX PROBABLY LEANED ON TRIM TAB ACTUATOR (WHICH IS A ROCKER SWITCH) AND RAN IT ALL THE WAY TO L. SIT COULD HAVE BEEN AVOIDED BY EITHER HAVING A COCKPIT DOOR OR BY PUTTING A GUARD OVER THE SWITCH.