What happened
On May 18, 2016, an An-12B, registration 4K-AZ25, was scheduled for a multi-leg cargo flight involving stops in Baku, Bagram, Dwyer, and Mary. The crew, which included the flight crew and several technical personnel, prepared for departure from Dwyer aerodrome. Following engine start-up procedures, the aircraft taxied toward the runway for a takeoff with Flaps 15. During the process, the flight mechanic noted that the temperature in Engine #3 had exceeded acceptable limits.
As the crew performed checklists, the captain ordered the propellers to be locked. While data suggests propellers #1, #2, and #4 were successfully locked, there is no evidence that the propeller for Engine #3 was secured. During the takeoff roll, the aircraft experienced significant rudder deflection and the crew likely applied differential control to manage torque. At a speed of approximately 120 km/h, the aircraft triggered a negative thrust signal for Engine #3. While thrust was increased on Engines #1, #4, and eventually #2, Engine #3 remained in ground idle mode throughout the roll.
As the aircraft approached the end of the runway at a speed of 220 km/h, a nose-up input was recorded, but the aircraft failed to lift off. The An-12B overran the runway and struck the ground, causing substantial structural damage and a subsequent fire. The accident resulted in 7 fatalities and 2 serious injuries.
Findings
- Engine #3 was operating in ground idle mode during the takeoff roll, despite the crew's focus on other engine parameters.
- Engine #3 failed to provide necessary thrust as the aircraft reached takeoff speeds.