What was found
WHEN GEAR WAS LOWERED FOR LANDING ON APPROACH TO ORD THREE RED UNSAFE LIGHTS WERE ILLUMINATED. A GO-AROUND WAS PERFORMED AND QRH PROCEDURES WERE ACCOMPLISHED WITH SUCCESSFUL GEAR EXTENSION. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOOTING FOUND THE NOSE GEAR NOT EXTENDING HYDRAULICALLY. MAINTENANCE FOUND THE NOSE GEAR BUNGEE CYLINDER AT FAULT. THE BUNGEE CYLINDER WAS REMOVED AND REPLACED IAW MM 32-32-7. THE LANDING GEAR CONTROL VALVE WAS REPLACED AS A PRECAUTIONARY MEASURE AND THE SYSTEM WAS TESTED IAW MM 32-32-01.