EMB120 HAD LOGBOOK WRITE-UP OF PROP OVERSPD. FLC INSISTED ON A FLT CHK SINCE MAINT HAD OK'ED THE ACFT FOR SVC AFTER GND CHK. IN THE TFC PATTERN ON FINAL APCH R PROP AGAIN BEGAN TO OVERSPD AND MAINT OBSERVER ON BOARD SAID TO TAKE THE ACFT TO THE HANGAR. ACFT OTS FOR FURTHER CHKS.

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AS FO ON TRIP; WE WAITED IN MCO OPS FOR ACFT TO OPERATE FLT MCO-EYW. MAINT WAS BRINGING THE ACFT OVER FROM THE HANGAR AS IT HAD BEEN WRITTEN UP EARLIER IN THE DAY; DUE TO AN OVERSPD ON THE R PROP. NEEDLESS TO SAY WE CHKED THE MAINT LOG CAREFULLY DURING OUR PREFLT INSPECTION AND FOUND THAT THE PREVIOUS CREW HAD INDEED EXPERIENCED AN OVERSPD ON THE R (#2) PROP. THE WRITE-UP STATED THAT THE #2 NP WENT TO 105.1% AT 200 FT AGL ON SHORT FINAL AND WAS ACCOMPANIED BY A DECREASE IN TORQUE FROM APPROX 22% TO 13%. MAINT HAD CLRED THE ACFT FOR FLT WITH AN ENTRY TO THE LOG THAT STATED THAT THEY HAD GND CHKED THE #2 ENG AND PROP AND COULD NOT DUPLICATE THE OVERSPD CONDITION. AS A CREW; WE WERE A LITTLE CONCERNED ABOUT THIS OVERSPD AND THE FACT THAT A GND CHK SEEMED ADEQUATE TO DEEM THE ACFT SAFE FOR FURTHER SVC. THE CAPT THEN WENT INTO OPS TO TALK WITH THE MAINT SUPVR WHO HAD TAXIED THE ACFT FROM THE HANGAR. THE SUPVR SAID HE BELIEVED THAT THE OVERSPD HAD OCCURRED ON THE GND; AND SO ALL THAT WAS REQUIRED WAS A GND RUN AND CHK BEFORE RETURNING THE AIRPLANE TO SVC. THE CAPT THEN RECHKED THE WRITE-UP AND CONFIRMED THAT THE OVERSPD DID IN FACT; OCCUR IN THE AIR. MAINT THEN AGREED THAT AT LEAST A FLT CHK SHOULD BE PERFORMED BEFORE RETURN TO SVC. WE TOOK SHIP AROUND THE PATTERN FROM MCO RWY 17; WITH A MAINT MECH ON THE JUMP SEAT AS ON OBSERVER. THE CAPT FLEW THE TEST FLT; AND AT THE APPROPRIATE TIME HE CALLED FOR 'LNDG GEAR DOWN AND CONDITION LEVERS MAX.' I; AS PNF; DID ALL THE ABOVE AND AS USUAL; SLOWLY ADVANCED THE CONDITION LEVERS TO MAX. THE NP INCREASED STEADILY TO 100% ON BOTH ENGS AND STABILIZED FOR A SECOND OR 2. THEN; WITHOUT WARNING; THE NP ON THE #2 ENG SUDDENLY INCREASED TO 104.4%. THIS HAPPENED AT 700' AGL AND WAS ACCOMPANIED BY A SLIGHT YAW TO THE R AND THE EXPECTED SOUND OF PROPS OUT OF SYNC. THE CAPT REDUCED THE PWR ON BOTH ENGS; AT WHICH POINT THE NP ON #2 CAME BACK TO SLIGHTLY BELOW 100% AND REMAINED THERE UNTIL LNDG; A FEW SECONDS LATER. OUR ONBOARD OBSERVER/MECH SUGGESTED THAT WE TAXI THE ACFT STRAIGHT TO THE HANGAR. WE CALLED OPS TO SAY THAT THE TEST FLT WAS NOT SATISFACTORY. AS SOON AS WE SHUT THE AIRPLANE DOWN AT THE HANGAR; MAINT SEEMED VERY SURPRISED THAT WE WERE REFUSING TO ACCEPT THE AIRPLANE FOR SERVICE. THEY WERE APPARENTLY BASING THEIR SURPRISE UPON THE FACT THAT THE LIMITATION ON NP IN OUR FLT STANDARDS MANUAL STATES THAT TRANSIENT NP IS 110% FOR 20 SECONDS MAX. HOWEVER; BOTH THE CAPT AND I HAVE BEEN FLYING THE EMB120 FOR OVER 6 YRS EACH; AND HAVE NEVER SEEN AN NP FLUCTUATION OF THIS KIND. THIS EXPERIENCE; AND THE FACT THAT THE EMB120 HAS A HISTORY OF PROP PROBS; LED US TO THE BELIEF THAT THIS ACFT; IN THIS PARTICULAR CONDITION SHOULD NOT BE USED FOR SVC WITHOUT FURTHER INVESTIGATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: MAINT AND THE COMPANY WERE IN FULL AGREEMENT TO TAKE THE ACFT OTS AFTER FURTHER INVESTIGATION. THE FLT OPS MANUAL REF TO THE OVERSPD CONDITION HAS TO DO WITH APPLICATION OF TKOF PWR ON THE GND; 110% IS PERMITTED FOR A VERY LIMITED TIME. WAS NOT AWARE IF FAA GOT INVOLVED OR NOT BUT FEELS THEY PROBABLY WERE SINCE THE ACFT WAS REMOVED FROM SVC. HAS FLOWN THE ACFT FOR 6 YRS AND THIS WAS HIS FIRST EXPERIENCE WITH PROP OVERSPD. IS AWARE THE PROP HAS BEEN A PROB ON THE EMB120 BUT HAD NO SPECIFIC DETAILS.