Limited flight testing was conducted to evaluate the performance characteristics and functional suitability when operating on a blend of 10 percent ethanol alcohol with JP-4 jet fuel. Of the 37 hour flight test effort, 20.3 hours were conducted with ethanol blended fuel in the starboard PT6A-41 engine of a Beechcraft King Air 200. Data collection was conducted at 6,000 foot intervals from ground level up to 30,000 feet utilizing steep climb to interval altitudes, continuous climbs and endurance cruise profiles. Ethanol fuel blending was not conducted before flight but rather during flight utilizing a separate onboard ethanol tank with associated fuel lines and mixing valves. This procedure allowed for consistent control of the desired 10 percent fuel mixture and allowed for a stable mixture with no possibility of phase separation. While a noticeable power reduction was present when operating with an ethanol mixture, no detrimental conditions were noted. In addition, an engine hot section inspection was performed both before and after flight test operations were completed. No degradation of components were noted by the overhaul facility and the only fuel related part change was a fuel control unit diaphragm. This part change was accomplished during the post flight test inspection as a precaution only.
Flight Testing with Etanol in Turboprop Engines
1990
10 pages
Report
No indication
English
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