Prime Minister Narendra Modi on Monday inaugurated the Hindustan Aeronautics Limited's helicopter factory -- the country's largest chopper manufacturing facility -- in Tumakuru district of Karnataka. Bengaluru-headquartered HAL plans to produce more than 1,000 helicopters in the range of 3-15 tonne with a total business of more than Rs 4 lakh crore over a period of 20 years at this facility in Gubbi taluk, officials said.