What was found
DURING AN STC FLIGHT TEST, THE AIRCRAFT WAS FLOWN TO A 45 DEGREE ANGLE FOLLOWED BY A PUSH-OVER RESULTING IN A ZERO GRAVITY CONDITION. THE LOW ENGINE OIL PRSSURE WARNING ANNUNCIATED AND BOTH PROPELLERS FEATHERED. ENGINE POWER WAS REDUCED AND OIL PRESSURE STABILIZED. WHILE THE SISTER ENGINE/PROPELLER RECOVERED, PROPELLER WENT TO OVERSPEED GOVERNING. THE CREW ELECTED TO SHUT THE ENGINE DOWN INFLIGHT. MFG WILL INVESTIGATE THIS EVENT AND WILL ADVISE OF ROOT CAUSE ONCE DETERMINED.