What was found
PILOT REPORTED ON TAKEOFF, HE INCREASED THE COLLECTIVE TO GET THE HELICOPTER LIGHT ON THE SKIDS PAUSING FOR A FEW SECONDS SO THE ROTOR RPM STABILIZED THEN CONTINUED THE TAKEOFF. JUST ABOUT 3 FT OFF THE GROUND, MOVING FORWARD INTO FLIGHT THE LOW RPM AUDIO SOUNDED AT THAT TIME THE HELICOPTER WAS OFF THE CONCRETE PAD OVER ROUGH TERRAIN GOING DOWN SLOPE WITH THE AUDIO STILL SOUNDING. THE PILOT QUICKLY CHECKED THE THROTTLE TO CONFIRM THAT IT WAS IN THE GATE, AUDIO STILL SOUNDING, ROTOR RPM BELOW 350. RETURNED TO HELIPAD. REPLACED FUEL CONTROL. AIRCRAFT RETURNED TO SERVICE WITH NO FURTHER DIFFICULTIES. (K)