June 18, 2012 : HAL has floated a bid for the supply of a turboprop engine for the in-development HTT-40 ab initio trainer programme. For the three-tonne basic trainer, HAL has stipulated to turboprop OEMs that it requires an operating envelope of Mach number 0-0.6M, calibrated air speed of maximum 500 km/h and ceiling altitude of 7,000-metres.

The engine should be capable of operation in dry and humid tropical climate as well as in saline sea side environment. It should be capable of care-free handling and surge free operation throughout the flight envelope. HAL will look to procure 16 engines outright from the manufacturer, and build 108 under license under an initial contract, following which it could increase the number of license built units. HAL will be taking great care with the engine selection and integration on the HTT-40 considering that it was the problem of frequent engine cutting out on the HPT-32 that caused most incidents in the air. While the Lycoming AE0-540 piston engine is certified and safe, integration issues meant that there were several problems with transmission and performance, creating a highly unsafe fleet in the HPT-32. HAL will be looking to work around such potential pitfalls right from the drawing board.

The HTT-40, first unveiled as a model at Aero India 2011, will progressively replace India's HPT-32 Deepak trainers, that have been grounded since July 2009. The Indian Government also recently placed an order for 75 Pilatus PC-7 Mk.2 basic trainers.