These almost definitely pertain to the supply of Adour Mk.951 turbofan engines for the BAE Hawk license build. It is not clear yet if the investigation could also delve into other engine contracts beyond that stipulated timeframe. Apart from the Hawk, RollsRoyce aero engines currently power the Indian Air Force’s Jaguar fighter-bombers and C-130J Super Hercules transports.
It won’t happen for sure, but here’s hoping the CBI gets to do some digging at HAL too. For a company that has spent half a century doing nothing but cookie-cutting aircraft and engines, there’s plenty of potential muck to be revealed there.