What was found
AFTER TAKE-OFF AT APPOX.350 FT OFF THE GROUND, NR 2 PROP BEGAN TO CYCLE IN AND OUT OF FEATHER. CREW PULLED BACK POWER, AND RETURNED TO FIELD. MAINTENANCE CREW REMOVED AND REPLACED NR 2 TORQUE SIGNAL CONDITIONER UNIT, DID A TEST FLIGHT, TEST FLIGHT FAILED. SAME CONDITION AS BEFORE, EXCEPT THIS TIME NR 2 ENGINE WAS SHUT DOWN. MAINTENANCE CREW TROUBLE SHOT THE BETA LOCK OUT SYSTEM, FOUND THAT THE SWITCH (6141S4) WAS STUCK IN THE NORMALY CLOSED POSITION. R&R SWITCH, GROUND CHECK WAS SATISFACTORY. TEST FLIGHT WAS ALSO SATISFACTORY.