A HESA IrAn-140 passenger plane, operated by Sepahan Airlines, crashed shortly after takeoff from Tehran-Mehrabad Airport, Iran. The aircraft operated flight 5915 to Tabas, Iran, carrying 42 passengers and six crew members. It was heavily loaded and 190 kg over the maximum takeoff weight. Weather was normal for Mehrabad Airport with an ambient air temperature 35øC and a 10 knot crosswind. For departure the crew selected 10ø of flaps, which was not approved according to the Standard Operating Procedure (SOP) of the airline. Additionally the crew did not set the elevator trim tab and the rudder trim tab to the positions complying with the requirements of the AFM. The elevator trim tab was set to -2ø instead of 0ø or +6ø depending on the aircraft CG position. The rudder trim tab was not set to the neutral position, its angle before take-off was about -3ø. The flight was cleared for takeoff from runway 29L. During the takeoff roll, the no.2 engine suffered an automatic shutdown. Two seconds later the captain rotated the aircraft at the speed of about 219 km/h (whereas 224 km/h was the recommended speed). Immediately after rotating, the captain noticed that the engine had failed and stated this to the co-pilot. After lift-off the aircraft deviated to the right from runway course, climbed around 40 m. The failure continuous warning chime and light then activated by about 14 seconds delay. The no.2 propeller was not feathered by the flight crew and it took 17 seconds, after engine shutdown, for the auto feather to kick in. By then the aircraft already had lost airspeed and altitude. The aircraft stalled and crashed in the area of urban utility service at the side of a highway, at a distance of about 3000 m from the runway threshold. The aircraft broke up and a fire broke out, destroying most of the fuselage. The IrAn-140 is an Antonov 140 turboprop aircraft, built under license by HESA in Iran. Sepahan Air, which is a division of HESA, operated six IrAn-140’s at the time of the accident. Causes: The accident investigation team determined that the main cause of this accident was combination of: 1. Electronic engine control (SAY-2000) failure simultaneously with engine No. 2 shutdown, just about 2 seconds before aircraft lift-off. 2. AFM Confusing performance chart resulted the pilots relying on performance calculation that, significantly over-estimate the aircraft MTOM. Contributing Factors to the accident were: 1. Aircraft flight manual unclear procedure, including the procedure for calculating maximum allowable take-off weight, VR and V2 and ambiguity in the climb segment definition and applications. 2. Crew performance, including: – PIC rotated the aircraft at the speed of about 219 km/h (whereas 224 km/h is the speed recommended by the AFM table 4.2.3) – The crew failed to perform the manual propeller feathering procedure for the failed engine. – The PIC’s decision to fly with the aircraft, notwithstanding, had about 190 kg overweight. – Aircraft fuel was about 500 kg more than required fuel for the accident flight. 3. The appearance of negative thrust from the unfeathered propeller blades at takeoff were not considered during the aircraft certification tests, as it was considered improbable. However, in the accident flight the negative thrust did appear and affected the flight performance.