As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF FROM KOPF,WHILE CLIMBING THROUGH FLIGHT LEVEL 15000, RIGHT HAND ENGINE N2 BEGAN SURGING. THROTTLE WAS BROUGHT BACK TO IDLE AND ENGINE STABILIZED. AFTER APPROXIMATELY 20 MINUTES WHILE IN A HOLDING PATTERN, RH ENGINE N2 AGAIN BEGAN SURGING. LANDED IMMEDIATELY WITHOUT INCIDENT INTO KPIE.