What was found
MCO - FLT 2998 - EN ROUTE FROM BWI TO FLL, AN APU OVERSPEED CONDITION OCCURRED AND THE APU SHUTDOWN IN FLIGHT. WITH THE NR 1 ENGINE CSD ALREADY ON MEL, THE FLIGHT DIVERTED TO MCO. FLIGHT LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE APU ELECTRONIC THREE SPEED SWITCH. OPS CHECK GOOD. CLEARED THE NR 1 ENGINE CSD MEL BY REPLACING THE NR 1 ENGINE CSD LOW OIL PRESSURE SWITCH (P/N 697902E). OPS CHECK AND LEAK CHECK GOOD. (M)