The private certificated pilot was cleared to taxi for takeoff and was proceeding toward the departure runway in a light, single-engine airplane. The pilot saw a four-engine military C-130 turboprop airplane that appeared to be doing an engine run-up, about 300 feet to the left of his taxiway. In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the pilot, the pilot reported, "I stopped short, and contacted Nashville ground 121.9, stating that I request further taxi instructions since a C-130 is running engines with exhaust blast toward me." The controller stated "...proceed your discretion." The pilot continued to taxi behind the C-130, and his airplane was struck by the propwash. The pilot's airplane was blown sideways and overturned. Paragraph 11, Jet Engine Exhaust, of the FAA's Advisory Circular AC 90-23F Aircraft Wake Turbulence, notes that light aircraft need to maintain adequate separation from jet engine blast during ground operations.