Incident Overview
On 21 May 2010, a Mi-8T helicopter with registration OK-XYC, operated by AEROCENTRUM, spol. s r.o., was conducting external load operations in Prague. During the transport of cooling towers between Letenská pláň and a building at Na bojišti 5, a wooden beam separated from the slung load and fell into the Vltava River. The beam was not part of the load itself but had been placed underneath the cooling towers to facilitate handling and prevent contamination. The helicopter crew did not notice the beam falling. No injuries were reported, and the aircraft sustained no damage.
Flight Operations
The operation involved the exchange of four cooling towers (EVAPCO units) using a 60-meter slung line. The first load was successfully delivered. While picking up the second load, the beam became dislodged. The witness reported the falling beam to the municipal police at approximately 9:32 local time. The crew continued with the remaining two transports, which were completed without further incident. The day's operations concluded about 60 minutes behind schedule.
Investigation
The Czech Accident Investigation Institute (ÚZPLN) was notified by the police and launched an investigation. The team included Ing. Zdeněk FORMÁNEK as chairman and Ing. Josef PROCHÁZKA and Ing. Jan ZELINKA as members. The investigation found that the beam had been placed under the cooling towers during preparation by riggers. A pre-flight inspection checked for loose items on the towers. The final report did not provide a probable cause for the beam's detachment.