Hill Helicopters has completed the first run of its clean-sheet GT50 turboshaft.

At 03:51 BST on 20 July 2026, the starter accelerated Prototype No. 1 to 15% N1 and the engine fired. During its first self-sustaining run, Prototype No. 1 reached 55% N1 and operated stably at commanded speed for five minutes, with no issues observed during the run.

The GT50 thus becomes the first clean-sheet helicopter turboshaft independently developed by a British manufacturer to achieve a first engine run since the Rolls-Royce Gem did so in 1969.

The result moves GT50 into the next phase of engine testing for the HX50 helicopter programme.

Before introducing fuel and ignition, the team checked the engine’s supporting systems and completed starter-driven cold-crank tests. Prototype No. 1 was extensively instrumented to measure temperatures, pressures, rotational speeds, flow rates and vibration throughout the test programme.

GT50 Prototype No. 1 comprises 438 complex precision parts, with its manufacture involving 71,668 machining and production operations.

Hill’s published design targets for GT50 include 400 hp maximum continuous power, 440 hp take-off power for five minutes at up to 10,000 ft and ISA +15°C, and 500 hp emergency power for 30 seconds. The engine has a target weight of 100 kg, target fuel consumption of 35 US gallons per hour at maximum continuous power, and a published TBO target of 5,000 hours or 20,000 cycles, on condition. Its planned production control architecture is a dual-channel Hill FADEC with manual reversion.

‘GT50 is born. It works. It sounds amazing. After four intense months manufacturing components, building and instrumenting the first engine and developing the test cell, GT50 took its first breath. We have taken the idea of making a new aircraft and engine that could change everything and dragged it kicking and screaming into vivid reality. Our team made this happen.’

— Jason Hill, Founder and Chief Engineer, Hill Helicopters

Two members of Hill’s engine team reflected on the result:

‘When the engine lit and accelerated away, I was absolutely ecstatic — and slightly numb as well. I could not believe that it had gone so well. The mood after the engine became self-sustaining was one of quiet satisfaction mixed with elation.’

— Steve Hill, Chief Engine Aerodynamicist, Hill Helicopters

‘We approached the first run conservatively, beginning with the supporting systems and starter-driven cold-crank tests before introducing fuel and ignition. Seeing the engine light and then become self-sustaining was an incredible moment.’

— Eric Welch, Chief Electrical Engineer and Avionics, Hill Helicopters

Hill will now run GT50 across its full speed range, conduct acceleration and deceleration ramps, and collect the data needed to map the full-authority digital engine control (FADEC) and develop the automatic-start sequence.

At the centre of the programme is Hill Helicopters’ Production Centre One (PC1) in Stafford, where design, development, production and assembly functions are brought together. PC1 supports Hill’s vertically integrated approach: developing the HX50, GT50 engine and Hill Digital Cockpit as one programme while bringing critical component development and manufacturing capability in-house.

The GT50 first run is one step on Hill’s road to what it calls General Aviation 2.0, an end-to-end approach to aircraft development and ownership intended to make personal aviation more attainable and better supported.

An HX50 Update & AMA focused on the GT50 first run will be livestreamed on Hill Helicopters’ YouTube channel at 17:00 BST on 5 August 2026. Featuring behind-the-scenes footage and first-hand reflections from the team, the programme follows the GT50 through manufacture, assembly and testing to its first self-sustaining run. It will remain available to watch here:

About Hill Helicopters

Based in Stafford, United Kingdom, Hill Helicopters is developing the HX50, a clean-sheet, five-seat private helicopter for personal aviation, together with its purpose-designed GT50 turboshaft and Hill Digital Cockpit. The company is integrating aircraft, engine and cockpit development within a single programme. For more information, visit www.hillhelicopters.com.