NEW DELHI, Sept. 22 -- Hindustan Aeronautics Limited (HAL) may have delivered the first batch of HTT-40 basic trainers to the Indian Air Force, but a steady supply of engines from US firm Honeywell remains critical to keeping the Rs.6,838-crore programme on schedule, officials said. The state-owned aerospace firm hopes Honeywell will resolve supply-chain bottlenecks and stabilise deliveries of TPE331-12B turboprop engines from next year, they added. The IAF had ordered 70 basic trainers three years ago to train rookie pilots. HAL was to deliver 12 aircraft in 2025-26 but failed to deliver any due to the engine shortage. Honeywell began supplying engines a few months ago and has assured HAL of timely deliveries. "There is an engine-related issue as Honeywell has tier-1 and tier-2 supply chain issues. The firm has promised us six engines by December. It is looking for alternative sources (to overcome supply chain bottlenecks)," HAL chairman and managing director Ravi K said. "The supplies are expected to stabilise from next year. Aircraft production is not an issue; it's on track," he told HT. On September 18, HAL handed over three HTT-40s and two LCA Mk-1 trainers to the IAF, besides four Dhruv NG civil helicopters to Pawan Hans Limited. The HTT-40 will be used for Stage-I flying training, currently conducted on Swiss-origin Pilatus PC-7 MkII aircraft. The tandem-seat trainer has modern avionics, an air-conditioned cockpit, hot refuelling capability and zero-zero ejection seats....