What was found
BEH - FLT 3488 - AFTER TAKEOFF, THE NR 2 ENGINE BEGAN TO SURGE IN RPM AND TORQUE. THE CREW REDUCED POWER, BUT THE ENGINE CONTINUED TO SURGE. THE CREW ELECTED TO PERFORM A PRECAUTIONARY SHUT DOWN AND RETURNED TO BEH WITHOUT INCIDENT. THE PROBLEM COULD NOT BE DUPLICATED IN BEH, SO THE AIRCRAFT WAS FERRIED TO DTW FOR FURTHER TROUBLESHOOTING. MAINTENANCE PERSONNEL REPLACED THE HMU. ALL SYSTEMS OPERATED SATISFACTORILY. (X)