Iranian investigators have indicated that the HESA IrAn-140 involved in the take-off crash in Tehran last year was operating above its weight limit.

The Civil Aviation Organisation states that a “failure to observe” load-calculation procedures had resulted in the aircraft, a licence-built Antonov An-140, being overweight.

But the probe into the Sepahan Airlines accident, on 10 August last year, points to several elements which contributed to the crash, including the high air temperature and wind conditions.

IrAn-140 crash

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While the inquiry has yet to be finalised – a draft final report is being prepared for Ukrainian and Russian authorities – it indicates starboard engine problems during the take-off roll.

Various tests have been conducted on the engine, fuel-control and fuel-distribution systems. Among the scenarios examined were the possibility of wake turbulence affecting the aircraft.

The engine-control system, the CAO suggests, showed “improper performance” before the aircraft lifted off, although the authority has not given full technical details of the event.

Forty-eight occupants had been on board the aircraft, which was bound for the eastern Iranian city of Tabas, but only a handful survived. The inquiry says that the amount of fuel on board the turboprop led to an intense fire.

Source: Cirium Dashboard