Complex sentence: The first training courses at No.3 EFTS were not conducted by RAAF instructors under the auspices of EATS but by Essendon's civil organisations under contract to the government, using privately owned de Havilland Tiger Moths and Gipsy Moths.
Split into simpler sentences: The first training courses at No.3 EFTS were not conducted by RAAF instructors under the auspices of EATS but by Essendon's civil organisations under government contract. The training aircraft were privately owned de Havilland Tiger Moths and Gipsy Moths.