US company Honeywell announced on 11 June that it had delivered the first three TPE331-12B engines to Hindustan Aeronautics Limited (HAL) for use on the latter’s HTT-40 basic trainer aircraft.
The HTT-40 turboprop is scheduled to become an indigenous basic trainer in the Indian Air Force (IAF), and production of the aircraft has already been under way. Actually, two series-produced HTT-40s are currently flying with used TPE331-12B engines that powered the prototype.
Ravi K, Chairman and Managing Director of HAL, explained: “These deliveries mark a significant milestone for the HTT-40 programme, and we’re confident future engine deliveries will continue on schedule.”
He was alluding to the fact that these engine deliveries had been delayed. Under Honeywell’s original US$100 million contract inked in July 2022, the first of 88 engines were supposed to be delivered last September. Bottlenecks in the global supply chain were blamed for delays.
The IAF ordered 70 HTT-40 trainers on 7 March 2023. Under the US$388 million contract, HAL was supposed to deliver the first dozen aircraft to the IAF in FY2025-26.
Honeywell will provide the first 16 TPE331-12B engines from the USA, before production transitions to HAL in India for the 72 remaining propulsion units.
Honeywell noted, “The milestone extends Honeywell’s decades-long collaboration with HAL, and advances India’s efforts to expand in-country aerospace manufacturing and long-term support.”
Thandava Edara, Vice President of Engineering and Head of Aerospace Engineering, India, Honeywell Technology Solutions, stated, “The TPE331’s single-shaft design delivers immediate throttle response, which is critical for pilot training.”
Honeywell added, “HAL’s experience with the TPE engine family will support long‑term operation and maintenance of the HTT‑40 aircraft.” The HTT-40 currently boasts 56% local content, but this will rise beyond 60%.
The IAF currently relies on a fleet of Pilatus PC-7 Mk II trainers, 75 of which were purchased in 2012. However, plans to purchase 38 more will scuttled when India’s Ministry of Defence suspended dealings with Pilatus over accusations of integrity breaches.
Edara added, “Our work with HAL and the Indian Air Force underscores our shared commitment to strengthening local manufacturing, assembly and long‑term support capabilities in India.” Indeed, HAL will expand its in-country repair and overhaul capabilities.
Interestingly, HAL also uses TPE331-5 engines on Dorner 228 aircraft, and Honeywell provided transfer of technology for manufacturing and repair of these engines.
There are 18 engine models and 106 configurations in the TPE series. Honeywell claimed the TPE331 is “one of the most reliable and proven turboprop engines in the world”. It pointed out more than 13,000 engines have been produced to date, accumulating more than 122 million flight hours.
by Gordon Arthur
