The Bulgarian defense ministry has opened a 20 million lev ($14.2 million/10.2 million euro) tender for reconstruction and maintenance of four Mi-17 helicopters, a notice in the EU’s procurement journal indicated on Thursday. The value of the contract does not include value added tax, the notice published in the Tenders Electronic Daily (TED) showed. The contract has duration of 84 months. Bids can be submitted until May 19.