Space Shuttle preflight hypergol oxidizer and fuel loading were monitored using a nonintrusive flow measurement system (NFMS) during preflight operation. A pair of 4-megahertz ultrasonic transducers measured the flow rate using a transit-time flow measurement technique. Using wireless cellular phone technology, flow-rate data was monitored and recorded. Excellent correlation was observed between the flow profiles measured using the proposed nonintrusive ultrasonic flowmeters (UFM's) and those made from conventional intrusive turbine meters (TFM). Based on the preliminary tests, it is concluded that the nonintrusive method of flow measurement has the same or higher accuracy, is simpler, and costs less than the existing TFM. Benefits of UFM's include a highly flexible, cost-effective, reliable, hazard free, and streamlined hypergol operation. Redundant installation of ultrasonic flowmeters was recommended for a few more launches prior to the replacement of the existing TFM. Werlink, Rudolph and Kelley, Andrew and Margasahayam, Ravi Kennedy Space Center NAS10-11943...