A Hindustan Aeronautics Limited-designed and developed Hindustan Turbo Trainer-40 HTT-40 trainer aircraft. HAL said it expected production clearance for the HTT-40 by the end of this year

HTT-40, the indigenously-built basic trainer aircraft, on Friday cleared a challenging milestone — its first spin test — Hindustan Aeronautics Ltd. said.

A few more tests are due to follow before the aircraft can get its operational certification, likely in mid-2019, according to a person familiar with the programme.

DAC Approval

HAL said it expected production clearance for the HTT-40 by the end of this year. The Defence Acquisition Council has approved buying of 70 HAL-built basic trainers for the Indian Air Force. The HTT-40, when acquired, will join the 75 Swiss Pilatus PC-7 Mark II trainers that are already in service.

Congratulating the design and project team, HAL CMD R. Madhavan said, “The successful start of the spin testing gives a boost to HAL and also restores [its] credibility in successfully designing a spin-worthy aircraft.”

Around 1.30 p.m., test pilots Gp Capt K.K.Venugopal (Retd), and Gp Capt S. Chaki (Retd) flew the aircraft and achieved the feat.

The spin test is the most crucial phase in developing a safe and airworthy aircraft, according to HAL. Novice military pilots begin their flying careers with a basic trainer and then graduate on to fighters and transport planes.

“This is a big boost [for the team]. We got the spin right after two generations, the last was in the 1980s for the Kiran,” said the official associated with trainer development.

A statement said, “HTT-40 began the most awaited phase of the ‘spin test’ by successfully entering into a two-turn spin and subsequently recovering with the appropriate controls.”

Arup Chatterjee, Director (Engg and R&D) said the spin trial met the test points of PSQR or `preliminary specifications qualitative requirements'; the completion of the spin test is the last milestone to be cleared before the aircraft enters service.

The first spin test has been met five years since HAL took up the basic trainer project design in August 2013 at its own expense of around ₹350 crore. It has moved at a "breakneck speed" and already cleared the prior important stage of stall testing.

The development comes as a morale booster to the State-owned defence aircraft manufacturer which has braved negative sentiment in recent months for being left out of the IAF's much-debated Rafale fighters acquisition program.

HTT-40, too, had been earlier rejected by the IAF which opted for the imported Pilatus.

Over the past months, HAL’s Aircraft Research and Design Centre (ARDC) had conducted extensive wind tunnel tests and analysed mathematical models to arrive at the requirements of the spin test. "The entire study is put to test during those first few moments of spin testing," it said.