What was found
ACFT HAD A "FIRE" WARNING INDICATION FOR THE NR 2 ENG ON APPROACH INTO MSP. FLIGHT CREW COMPLIED WITH QRH AND ULTIMATELY ACTIVATED THE FIRE BOTTLE AND SHUTDOWN THE NR 2 ENGINE. CREW COMPLETED A SINGLE ENG APPROACH TO AN UNEVENTFUL LANDING. MX DID NOT FIND ANY EVIDENCE OF AN ACTUAL FIRE, NO OIL OR FUEL LEAKS, AND NOT ANY PNEUMATIC SYS LEAKS EITHER. THEY DID CONFIRM THAT THE NR 2 FIRE DETECTOR CONTROL UNIT FAILED AND REPLACED IT. MX ALSO REPLACED THE NR 2 ENGINE UPPER FIRE EXTINGUISHER BOTTLE.