All three aircraft are kept in fully airworthy condition. In 1999, two years after being delivered, only one airframe was in airworthy condition. The aircraft had not been classified as being airworthy. The aircraft are being maintained by GJD Systems to a fully airworthy condition. The aircraft was in an airworthy condition at departure. No person may operate an aircraft unless it is in an airworthy condition. Vintage jet aircraft in airworthy condition, however, are much rarer due to technical complexity. One Spitfire is kept in airworthy condition in the Israeli Air Force Museum. The aircraft and crew were found to be fit, airworthy and certified. "Boeing Bee" has been completely restored and is potentially airworthy once again. It is these aircraft that form the bulk of airworthy "survivors" today. Now currently airworthy and flying for the SAA Museum! Only one Li-2 restored to airworthy condition exists in Europe. Repairs to airworthy status were considered financially inadvisable. Beech built three airworthy full-scale prototypes.