Carborough Downs Coal Mine was developed from a box cut using three entries, one for men and materials, one for the conveyor and one return portal. The initial drivage was conducted by drill and blast and each access was ventilated by a Flaktwoods 27 m3/s 1058 50 kW fan. The box cut fan installation was transferred from the sister mine in NSW and installed on the portal. After 18 months the shock losses in the fan to adit adaptor were severely affecting the ability to increase the number of development units operating in the mine. It was decided to perform a fan upgrade prior to the installation of the main fans and fan shaft in March 2009. The fan housing adaptor was modified to reduce the shock losses and the motors and gearboxes were upgraded at the same time. The planning processes, minor ventilation changes and supervision which were conducted to maintain mine ventilation during the overhaul period are discussed. The three Flaktwoods1058 fans were bolted into a shipping container and monitored for flow, pressure and vibration to suit the requirements of the Queensland legislation and the ventilation maintained with in the mine at 75 m3/s down from 145 m3/s with the original fans. The upgraded ventilation capacity achieved was 245 m3/s. Two of these fans are currently being used in series to ventilate the new conveyor drift with a design capacity of 28 m3/s at 1200 m through 1218 mm ducting.