What was found
YIP - CREW DISCOVERED FUEL VENTING FROM RIGHT WING AFTER TAKEOFF FROM YIP. UNSCHEDULED LANDING MADE, AIRCRAFT RETURNED TO YIP. NO EMERGENCY PROCEDURES REQUIRED. MAINTENANCE FOUND THE FUEL CAP TO BE DEFECTIVE DUE TO A WORN LOCKING PRONG. FUEL CAP WAS REPLACED WITH A SERVICEABLE PART. AIRCRAFT WAS RUN UP AND FUEL CAP SHOWED NO LEAKAGE OF PRESSURE DURING ENGINE RUN. (M)