sentences:  The aircraft has been produced in two principal models, these being the "Fantrainer 400", powered by a Allison 250-C20B, and the "Fantrainer 600", which was powered by a Allison 250-C30.According to aerospace publication Flight International, the market had a more favourable reaction to the "Fantrainer 600" during the 1980s.In August 1982, the Royal Thai Air Force signed a contract with RFB to purchase 47 aircraft, 31 of the model 400 and 16 of the 600.