THE NON-RATED PLT STATED THAT DURING A LOCAL FLT, HE FLEW OVER A WATER WELL DRILLING OPERATION TO SURVEY THE AREA. HE REPORTED THAT HE CIRCLED AT 500 FT 'INDICATE'. AFTER SURVEYING THE AREA, HE INITIATED A CLIMB, BUT THE ENG LOST POWER. SHORTLY AFTER THAT, THE ACFT STALLED & ENTERED A SPIN. THE PLT WAS ABLE TO STOP THE SPIN & LEVEL THE WINGS; HOWEVER, THE ACFT IMPACTED THE GROUND. THE PASSENGER & 2 GROUND WITNESSES PROVIDE INFO THAT GENERALLY AGREED WITH THE PLT'S ACCOUNT OF THE OCCURRENCE. HOWEVER, 1 GROUND WITNESS ESTIMATED THAT THE ACFT HAD DESCENDED TO ABOUT 50 FT AGL & THE ENG LOST POWER AFTER THE PLANE HAD CLIMBED TO APRX 100 FT AGL. THE ELEVATION WAS ABOUT 190 FT. NO PREIMPACT FAILURE WAS FOUND, EXCEPT THE WIRE IN THE MIXTURE CONTROL CABLE HAD BEEN CRACKED ABOUT 3/4 OF THE WAY THRU. AT MEMPHIS, TN, THE 1551 CDT TEMP & DEW POINT WERE 86 & 55 DEG. ACCORDING TO ICING PROBABILITY CHARTS, CARB ICING COULD HAVE OCCURRED AT OR BELOW RATED POWER.