What was found
AIRCRAFT HAS RAISEBECK STC SA3593NM INSTALLED WHICH STATES THE PROPS ARE NOT TO BE OPERATED BELOW THE SET MINIMUM RPM. PRE PHASE INSPECTION RUNS REVEALED THIS CONDITION. IAW MFG SERVICE LETTER 61-254 THIS CAN CAUSE NO REACTION MODE VIBRATORY RESONANCE AND MAY RESULT IN HIGH STRESS IN THE BLADES. IT WAS RECOMMENDED THAT THE PROPELLERS BE REMOVED AND BE SENT TO A PROPELLER SHOP FOR INSPECTION. CUSTOMER DECLINED RECOMMENDATION. NO FURTHER ACTION WAS TAKEN AT THIS INSPECTION. BOTH THE LT AND RT PROPELLERS HAVE A TSO OF 957.9 AND A TT OF 2615.2