Accident Details
While cruising at an altitude of 6,000 metres, the aircraft experienced a structural failure when the tail separated. The aircraft then entered an uncontrolled descent and crashed in a wooded area approximately one kilometre from Cherkessk. Upon impact, the aircraft was totally destroyed. All 50 occupants were killed.
Investigation Findings
The tail was found about 1,600 metres from the main wreckage. Investigation revealed that the tail separated due to corrosion after the aircraft had been operated in a humid environment in Zimbabwe and the Democratic Republic of the Congo from 15 August 1994 until 28 December 1995.
Official Probable Cause
The official findings state that the accident was caused by a combination of the following factors:
1. Surface assessment, without the use of instrumental control methods, of the technical condition of the An-24 RA 46516 aircraft, leading to an unjustified conclusion and decision to extend its maintenance time between overhauls (MTO) and service life. 2. Violation of requirements when extending the overhaul life for the aircraft, without considering its long-term operation in a humid and hot climate. 3. Inconsistency of regulatory documents governing the establishment and extension of resources and service life for civil aircraft with flight safety requirements in modern conditions. 4. Violation of repair technology for aircraft and household equipment during repairs in aircraft repair plant (ARZ) conditions. 5. Imperfection of technological documentation for periodic maintenance in terms of determining the corrosion and corrosion-fatigue state of the aircraft structure in hard-to-reach areas. 6. Insufficient control of hard-to-reach areas of the lower fuselage structure for corrosion lesions during operation. 7. Failure to comply with prescribed anti-corrosion measures for the aircraft structure during repairs and in operation.