THE PLT-IN-COMMAND (PIC) & STUDENT PLT WERE ON AN AERIAL PHOTOGRAPHY FLT WHEN THE PIC NOTICED A LOSS OF ENG OIL PRESSURE. THEY SAW MEADOWLARK ARPT & BEGAN AN EMERGENCY APCH. THE PIC STATED THAT SHE RELINQUISHED HER PIC DUTIES TO THE STUDENT BECAUSE SHE BELIEVED HE HAD A HIGHER LEVEL OF FLYING EXPERIENCE. (THE STUDENT HAD TOLD HER THAT HE WAS A FORMER MILITARY PLT, BUT HAD NOT OBTAINED A CIVILIAN PLT CERTIFICATE.) WHILE ON FINAL APCH, THE ACFT WAS HIGH, SO THE STUDENT ELECTED TO MAKE A GO-AROUND AND A 360 DEG TURN. DURING THE TURN, HE RETRACTED THE FLAPS (LATER FOUND A 10 DEG). SUBSEQUENTLY, THE ACFT MUSHED INTO THE ROOF OF A HOUSE & CRASHED INTO A FENCE & PATIO OF AN ADJACENT HOME. AN EXAM REVEALED OIL ON THE UNDERSIDE OF THE FUSELAGE. THE OIL DRAIN SUMP PLUG,QUICK DRAIN,WAS FOUND IN THE OPEN POSITION & NO OIL WAS FOUND IN THE SUMP. THE FORWARD OIL BREATHER TUBE WAS CLOGGED. BEARING BABBIT MATERIAL WAS FOUND INTHE SUMP. THE OIL DRAIN O-RING WAS WORN, WHEN CLEANED/TESTED THE SUMP PLUG LEAKED.