1978 Finnish Air Force DC-3 crash
The Finnish Air Force DC-3 disaster occurred when a plane of this class crashed into Lake Juurusvesi in Rissala on 3 October 1978, killing all fifteen people on board. It was caused by a cracked exhaust valve, resulting from metal fatigue in an engine cylinder.
Source: Wikipedia — 1978 Finnish Air Force DC-3 crash (CC BY-SA 4.0)