The maintenance unit was located on the northern edge of Carlisle, just past the present Asda supermarket, and spread across several different sites. The smallest storage site of Harker was 0.7 km north east of RAF Kingstown and, together with Heathlands which was 0.5 km north, was on the opposite side on the A74 (now the M6). The largest site of Rockcliffe was 1.2 km north west and Cargo site was 1.5 km south west. The maintenance unit was used by the RAF to store and maintain various pieces of equipment ranging from aircraft engine parts to firearms, ammunition to office furniture, aircrew clothing and small hardware items.