After modeling an aircraft turboprop engine using SIMULINK$circledR$, performance simulation of PT6A-62 engine, which is main power plant of KT-1, was performed. For validation, performance parameters of the SIMULIINK model were compared with the simulated results by GASTURB program. It was confirm that the results by the SIMULINK model were well agreed with those by GASTURB within 1.07%, It was assumed that installation losses were bleed-air exteraction with a range from 0% to 5%, and power for accessories with a range from 0 to 20hp. In this investigation, it was found that the shafthorsepower was decreased by maxium 0.68%, but specific fuel consumption ratio was not effected nearly by these losses.