Explained: What Is HTT-40, the Trainer Aircraft Unveiled by PM Modi at DefExpo?

The trainer aircraft is yet another indigenous defence project, in a series of long-delayed Atmanirbhar initiatives, with a tempestuous past.

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New Delhi: The Hindustan Turbo Trainer-40 (HTT-40) basic trainer aircraft (BTA), which Prime Minister Narendra Modi unveiled at the DefExpo-2022 in Gandhinagar on Wednesday for the Indian Air Force (IAF), is yet another indigenous defence project, in a series of long-delayed Atmanirbhar initiatives, with a tempestuous past.

Under development by Hindustan Aeronautics Limited (HAL) since 2013, the HTT-40 received its provisional airworthiness certificate from the Centre for Military Airworthiness and Certification (CEMILAC) in Bangalore almost nine years later in June 2022. Its series production is expected to begin in Bangalore and Nashik in early 2023, after the IAF formally signed a contract with HAL to supply it 70 dual-seat HTT-40s, followed by an additional 38 BTAs.

Media reports indicate that delivery of the first batch of two HTT-40s to the IAF would take place some 20 months after the deal for them was closed – or sometime in late 2024 or early 2025 – followed by eight, and thereafter 20 aircraft annually.

Undertaken to replace the earlier HAL-designed ‘Deepak’ Hindustan Piston Trainer-32 (HPT-32), which was grounded in 2009 following recurring accidents in which several trainees and instructor pilots died, the HTT-40’s advent was initially hugely tentative and angst-ridden. This was because around 2012, IAF had outrightly declined to accept the indigenous BTA, deeming it too expensive compared to the 75 Swiss Pilatus PC-7 Mk II tandem-seat BTAs that the force had already agreed to import for $1 billion to provide basic instruction to its pilots.

The see-saw battle and acrimony between the IAF and HAL over the HTT-40 escalated in 2014, with the former declining to fund the project and leaving it solely to the public sector aircraft manufacturer to finance it. But once the BTA’s first prototype conducted its maiden test flight in early 2016, followed by a second prototype a year later, IAF interest in the indigenous HTT-40 was kindled. It was also, doubtlessly, boosted by PM Modi’s newly elected BJP-led government’s ‘Make in India’ programme in the defence sector that aimed at reducing materiel import dependence.

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But obstacles still persisted in progressing the HTT-40s development and eventual manufacture.

In mid-2019, HAL wanted the IAF to issue a request for proposal (RfP) before fast-tracking the HTT-40s series production, to facilitate the release of around Rs 200 crore by its board of directors in order to pay US’s Honeywell Garret to upgrade the trainers TPE331-12B single-shaft turboprop engine.

“By way of caution HAL’s board had stipulated that the money should be paid (to Honeywell) once the IAF issued an RfP so that recovery (of investment) was ensured,” former HAL chairman R. Madhavan had then told the Business Standard. This is why we urgently want an RfP from the IAF, he added as this money was needed to replace the TPE331-12B’s electronic engine controller with a full authority digital engine controller (FADEC) for enhanced thrust, before the BTA was cleared for manufacture.

The truculent IAF, however, maintained that it would issue an RfP only after the HTT-40 had completed its entire stall-and-spin trial cycle. HAL in response had argued that after its 2016 test flight, the HTT-40 had ‘amply’ demonstrated its ability to recover from three stall-and-spin cycles and that the IAFs demands were ‘extraneous’.

Furthermore, HAL also claimed that levelling the platforms from six spins to the left and right, as demanded by the IAF, would be resolved ‘incrementally’ in further trials. This aspect of stall-and-spin training is especially crucial for fighter pilots, who need to familiarise themselves with all departures from controlled flight alongside the responses and actions needed to recover from such perilous situations.

At the time, HAL is also believed to have held the IAF responsible for continually changing its benchmark for the trainers’ stall-and-spin capability, despite the HTT-40 having exceeded the air force’s initial staff qualitative requirements for the platform on numerous other parameters, as proven during flight testing.

Eventually, the IAFs RFP for 75 HTT-40s was issued to HAL in early 2021 along with a clause that included the option to acquire 38 more BTAs. Soon after, this is believed to have led to HAL transferring Rs 200 crore to Honeywell to modify its engine, an undertaking that was expected to be completed within 18-24 months thereafter.

Meanwhile, HAL sources said that the HTT-40 possessed advanced features like zero-zero ejection seats and multi-function displays and was capable of providing instrument, night flying and aerobatics instruction to trainee IAF pilots. Some 50-60% of the trainer – other than its engine and ejection seats – was indigenous in content and designed with a 6km operational ceiling, 450km range, +6G/-2G acceleration, a 6m/sec climb rate and 12:1 glide ratio. Industry sources said that armed with a mix of 250/500lb bombs, 12.7mm guns and rockets, the HTT-40 could also double as a light attack aircraft for employment in counter-terrorism operations.

An exhibit of the indigenous trainer aircraft HTT-40 (Hindustan Turbo Trainer-40) designed by HAL on display during the 12th edition of DefExpo, in Gandhinagar, October. 19, 2022. Photo: PTI/Atul Yadav

IAF woes to continue in the meantime

In the meantime, the IAF is reportedly continuing to face serviceability problems with its originally 75-strong Pilatus PC-7 trainer fleet, as it had failed to renew the maintenance contract after the extended warranty for them had expired in December 2016, a year after all their deliveries were completed. Consequently, the IAF was forced into sourcing PC-7 spares and components from the open market at great cost, or alternately, ‘cannibalising’ active trainers to keep the Pilatus fleet operational at the Air Force Academy in Dundigal, near Hyderabad.

Under the IAF’s revised training regimen for its pilots for 200-225 hours, instruction is divided equally between the Pilatus PC-7 MKII BTAs and BAE Systems Hawk132 advanced jet trainers (AJTs), of which some 104, mostly licence built by HAL, were in service.

Industry officials said inconclusive inquiries, launched in mid-2016 by the Ministry of Defence (MoD) into the alleged participation of a middleman in the PC-7 procurement, were responsible for delays in signing this maintenance contract. These investigations followed the recovery of documents by the Enforcement Directorate from the offices of a New Delhi-based businessman, under inquiry for financial wrongdoing in other materiel buys. The appropriated records reportedly indicated that the businessman had ‘facilitated’ the Pilatus procurement in return for a hefty fee.

Earlier, the issue of a ‘flawed’ trainer selection procedure, which reportedly included Pilatus employing a middleman to ‘enable’ the PC-7 contract, was flagged in January 2012 by Korean Aerospace Industries (KAI) that was also competing for the IAF’s BTA tender with its KT-1 platform. At the time, the MoD had dismissed KAI’s allegations as ‘baseless’ and signed the deal with Pilatus in May 2012, followed by 12 of its trainers a year later.

Successive editions of India’s Defence Procurement/Acquisition Procedure proscribe the use of middlemen or agents by military vendors to secure contracts. The Integrity Pact, which all materiel suppliers are mandatorily required to sign, stipulates that any deal would be terminated if it emerged that this undertaking with regard to employing agents had been breached at any stage of the contract, even after it was concluded. It also required the vendor to make a complete refund.

The MoD’s inquiry into the Pilatus purchase was also responsible for terminating the acquisition of 38 additional PC-7s, despite the MoD’s Defence Acquisition Council having approved their purchase in March 2015. Instead, the MoD and the IAF had decided that the BTA requirement would be made good by the HTT-40, of which the IAF eventually aimed on inducting some 115.

In conclusion, the IAF’s yo-yo attitude towards the HTT-40, with its off and on and on and off recalcitrant attitude, had needlessly delayed the indigenous trainer’s development. Perhaps, It remains to be seen if the IAF, as indeed the two other services, would not repeat such folly.