RAF Helperby, was a First World War era airfield near to the villages of Brafferton and Helperby in North Yorkshire, England. It was used initially by No. 33 Squadron RAF, and then later by No. 76 Squadron RAF in the home defence (HD) role. During the Second World War, the site was used as an ammunition supply depot, being operated by No. 92 Maintenance Unit RAF, and also by the USAAF. The site was known to have stored mustard gas and other chemical weapons during the period of the Second World War.