What was found
SAV - FLT 2645 - EN ROUTE FROM BWI TO JAX, THE APU OVERSPEED LIGHT ILLUMINATED AND THE APU SHUTDOWN IN FLIGHT. WITH THE NR 1 ENGINE GENERATOR ALREADY ON MEL, FLIGHT DIVERTED TO SAV. FLIGHT LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE RESET AND RERACKED THE APU CONTROL UNIT (MODULE M280) THEN LATER REPLAED IT AS PRECAUTIONARY. OPERATIONAL CHECK GOOD. CLEARED MEL ON NR 1 ENGINE GENERATOR BY REMOVING AND REPLACING THE NR 1 ENGINE GENERATOR, CSD AND OIL COOLER. OPERATIONAL CHECK GOOD. (M)