Let L-410 crash in Poti

The Let L-410 crash in Poti was an aviation accident involving a Let L-410M (Let L-410M) passenger aircraft of the company Aeroflot, which occurred on Tuesday 29 March 1983 in the Poti area; 6 people were killed.

Crash

The aircraft was operating domestic passenger flight G-70 from Poti to Sukhumi, and 15 passengers boarded it, including one who was not registered — E. P. Chitava, an instructor pilot of the Sukhumi aviation detachment. The airliner's take-off weight was 5685 kg with a centre of gravity of 28 % MAC, which was within permissible limits. At that time there was broken middle-level cloud in the sky, wind 210° 2 m/s, visibility up to 20 kilometres. At 15:16 local time (14:16 MSK), with 18 people on board, flight 70 took off from runway 10 of Poti Airport.

The pilots retracted the landing gear, and the flaps were extended to 15°, when 14 seconds after lift-off, at an altitude of 60 metres, with the aircraft flying at an indicated airspeed of 195 km/h, the rpm of both engines suddenly dropped. In the left engine the rpm dropped to 60 %, that is, to flight idle, but then began to increase again and by the 25th second after take-off had returned to the original 94.5 %. However, in the right engine the rpm continued to decrease after the drop and soon fell practically to zero. Since L-410 aircraft are not equipped with an automatic propeller feathering system, the right propeller continued to rotate in autorotation (windmilling) mode, thereby creating considerable aerodynamic drag. This imbalance led to a vertical load factor of 1.35 units appearing, and the elevator began to vibrate at high frequency, which continued right up to the crash.

The crew began to make a right turn, while altitude and speed were simultaneously decreasing. 1 minute 20 seconds after the start of the take-off run and 44 seconds after the start of the drop in engine rpm, the speed had already fallen to 130 km/h, so the aircraft entered a stall, and three seconds later, having entered a steep right bank, struck the treetops with its right wing. The pilots corrected the bank, but 38 metres after the first impact the airflow separated on the wing because of the low speed. The aircraft again entered a steep right bank and began to crash into the trees. Having ploughed through them for 50 metres, 88 metres from the point of first impact with the trees and 2240 metres south-east (azimuth 125°) of the Poti aerodrome reference point, the airliner, on a heading of 325°, crashed into marshy ground, after which it swung round and came to a stop. There was no fire, but the forward part of the fuselage was destroyed, killing both pilots and another four passengers, including the instructor pilot, that is, 6 people in total. The remaining 12 people (the check pilot and 11 passengers) were injured but survived.