The TPE331-12B engine is a single shaft turboprop engine with integral inlet and gearbox, two stage centrifugal compressor, power turbine, gearbox, three stage axial turbine and turbine exhaust diffuser as well as EEC for reliable power and outstanding operational characteristics.

The HTT-40 prototypes are powered by TPE331-12B engines and has been serving well since 2014. Entering into this 'Manufacturing & Repair license agreement for Honeywell TPE331-12B Turboprop engine' marks a major milestone in the execution of 70 HTT-40 aircraft contract with IAF. HAL is working closely with Honeywell for its support for export potential of HTT-40. HAL and Honeywell are exploring other areas such as 1MW Turbo Generators, manufacturing, Repair & Overhaul of TPE 331-10GP / 12JR engines for variants of Dornier.