Mi-8T Helicopter Crash in Tomsk Region Due to Tail Rotor Component Failure

No fatalities • на п.п. "Кедровый" Томской обл. Парабельского р-на

A Mi-8T helicopter, registration RA-22649, crashed in the Kedrovy area of the Tomsk region following a mechanical failure in the tail rotor assembly. The accident resulted in no injuries or fatalities.

On December 16, 2018, a Mi-8T helicopter, registration RA-22649, operated by JSC 'Avia-predpriyatie Yeltsovka,' was performing a scheduled personnel transport mission. The flight plan involved multiple stops between various settlements, including Kargask Prichal, Kedrovoy Promzona, 395 Mayskaya, and 572 Mayskaya. The crew arrived at the Kargask Prichal landing site at 01:00 and began pre-flight preparations at 01:30.

Following the takeoff at 02:35, the crew successfully completed five flight segments without incident. During the mission, the aircraft was refueled with 1386 kg of TS-1 fuel after the third flight. The crew had reported no maintenance issues prior to departure, and the weather forecast received via telephone did not preclude flight operations.

During the mission, the helicopter experienced a catastrophic failure of the tail rotor shaft assembly. The failure caused the aircraft to enter an uncontrollable left rotation and a loss of altitude, ultimately resulting in a collision with the ground in the Kedroty area of the Parabel district. There were no injuries or fatalities reported in the accident.

Probable cause

The accident was caused by the complete wear of the splines on a specific sleeve within the tail rotor shaft assembly, which destroyed the kinematic connection and prevented the pilot from adjusting tail rotor blade pitch. This wear resulted from a manufacturing defect where the sleeve's splines were not properly surface-hardened via nitrocarburizing. A contributing factor was the failure to inspect the sleeve for specific factory markings during the initial inspection.

Frequently asked questions

What happened in the 2018-12-16 Ми-8Т accident near на п.п. "Кедровый" Томской обл. Парабельского р-на?

A Mi-8T helicopter, registration RA-22649, crashed in the Kedrovy area of the Tomsk region following a mechanical failure in the tail rotor assembly. The accident resulted in no injuries or fatalities.

Were there any fatalities in the 2018-12-16 Ми-8Т accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 2018-12-16 involved a Ми-8Т, registration RA-22649, operated by ЗАО "Авиапредприятие "Ельцовка", at на п.п. "Кедровый" Томской обл. Парабельского р-на.

What was the probable cause of the accident?

The accident was caused by the complete wear of the splines on a specific sleeve within the tail rotor shaft assembly, which destroyed the kinematic connection and prevented the pilot from adjusting tail rotor blade pitch. This wear resulted from a manufacturing defect where the sleeve's splines were not properly…

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