LONDON, July 6 (Reuters Breakingviews) - Alstom’s (ALSO.PA) cut-price purchase of Bombardier (BBDb.TO) is revealing some nasty hidden costs. The French train maker’s shares dropped 7% on Tuesday after it forecast up to 1.9 billion euros in free cash outflows during the six months to the end of September as it tries to stabilise “challenging legacy projects” at the Canadian manufacturer. The unusually frank language hints at the gremlins beneath Bombardier’s bonnet. It doesn’t explain why Alstom Chief Executive Henri Poupart-Lafarge failed to secure an even bigger discount on the 5.5 billion euro purchase price. Analysts had already pencilled in a 410 million euro cash flow hit for the 2021 financial year. To achieve that forecast, the combined group will now need to generate an unlikely 1.5 billion euros of positive cash flow in the second half. That’s almost double the estimate for the whole of 2024, when Bombardier’s wrinkles should be ironed out. For shareholders, Poupart-Lafarge’s global ambitions are proving expensive. (By Ed Cropley) On Twitter http://twitter.com/breakingviews Capital Calls - More concise insights on global finance: Hong Kong IPOs join 21st century read more Glencore chairman ticks most boxes read more Beijing prices up cost of e-commerce data abuses read more Pharma primed for LBO hot potato read more Didi drives straight into politics read more