What was found
DURING TAKEOFF, ROTOR RPM DECAYED TO 97 PERCENT. WOULD NOT RECOVER. PILOT LANDED WITHOUT INCIDENT. ALL TROUBLESHOOTING REVEALED NO DISCREPANCIES, COULD NOT DUPLICATE PROBLEM. MAINTENANCE CHANGED GOVERNOR FOR PRECAUTION. REF: ALLSION C-30 IPC, CHAPTER 73-20-00, FIGURE 5, PAGE 2, ITEM 59.