Swift Fuel’s leadless alternative to 100LL appears to have come through a critical engine endurance test with flying colors at an FAA lab. In a report (PDF) released last week, researchers at the William J. Hughes Technical Center in Atlantic City said they found no problems with wear or engine deposits in a brand-new Lycoming 540 that was broken in and run on Swift Fuel for 150 hours. “There was no indication of excessive wear on any of the high-contact, high-stress parts of the engine, and the engine oil analyses showed minimal fuel dilution,” the researchers concluded. “There was no evidence of excess fuel nozzle deposits or fuel maldistribution. Cylinder combustion deposits, including spark plugs, valves, and piston face deposits, were light. Varnish and sludge buildup were light.” The fuel tested was made in a refinery, rather than from the biomass process Swift hopes to use. The researchers recommended that further tests be done using biomass-sourced fuel. Although the tests went well, the results weren’t perfect.
The engine was difficult to start cold, although it fired right up when it was hot. Also, the secondary fuel pump diaphragm had stretch marks on it. While the pump’s performance degraded noticeably over the length of the test, it remained in spec. The researchers apparently had no recommendations on the cold-start issue but said they’d like to see further testing on the action of the fuel on the fuel pump diaphragm.