When the radio signals continued night after night, Mantz said she must be running the right-hand generator-equipped engine to recharge the battery. Asked whether she would have enough fuel, he explained that she could recharge the battery by running the engine at only 900 RPM burning as little as 6 gallons per hour. TIGHAR verified those numbers with tests at Covington Aircraft Engines in Oklahoma using the same type of engine and generator that were on NR16020.