The casting phase for the GT50 engine has reached completion, with enough high-quality superalloy components produced to build three complete engines. This strategic approach provides not only backup units but also enables experimental tuning and optimisation during testing.

Key achievements:

• High-pressure turbine blades – Now being cast reliably with consistent quality
• Low-pressure turbine blades – Complete sets ready for the power turbine assembly
• Structural core components – All essential framework elements successfully manufactured
• Surface finish excellence – Components emerging with intact trailing edges and accurate throat areas
• Controlled shrinkage – Manufacturing processes properly accounting for material behaviour during cooling

The quality standards being achieved represent a significant accomplishment, with Mark's casting team consistently producing components that meet the exacting specifications required for high-performance turbine operation.

Seven variants have been produced for what would typically be a single-component application. The strategic rationale behind multiple variants:

• Spare components – Anticipating potential damage during initial testing and limit-pushing experiments
• Throat area optimisation – The gap between turbine blades controls mass flow from compressor to turbine, requiring empirical validation
• Nominal geometry version – Represents the design intent assuming optimal component performance
• Cut-back geometry version – Features reduced blade profiles with enlarged throat areas for safer initial operation
• Progressive testing strategy – Allows the team to start with conservative parameters and gradually approach full performance specifications

This approach keeps the compressor away from its surge line and maintains cooler operating temperatures during early test runs, minimising the risk of catastrophic failure while the team builds operational experience.

Post-casting process workflow:

1. Heat treatment (currently underway)
2. Precision machining of mating faces and sealing surfaces
3. EDM (Electrical Discharge Machining) operations to cut cooling slots
4. Final EDM work to create detail features for metallic sealing rings
5. Quality verification and engine installation preparation

The annular combustor represents one of the most complex thermal management challenges in the engine, and all components for three complete combustor assemblies are now manufactured and awaiting final assembly.

Comprehensive component inventory includes:

• Inner rings – Roll-formed, precisely sized, and drilled with carefully positioned holes
• Outer rings – Featuring sliding joints to accommodate thermal expansion during operation
• Joining rings – Engineered to allow the combustor to "breathe" as metal temperatures reach extreme levels
• Complex pressed forms – Deep-drawn sections developed through combined simulation and experimental methods
• Combustor head assembly – Complete with impingement cooling holes and heat shield elements
• Gooseneck sections – Deep-drawn components that curve into the nozzle guide vane mouth

Each ring has been manufactured with exacting tolerances and features a unique, carefully controlled profile. The ability to quickly swap combustor configurations during testing, particularly for adjusting primary/secondary dilution holes and impingement cooling patterns, provides crucial flexibility without requiring complete new builds.

The vane diffuser, a crucial component that conditions airflow from the compressor, is currently undergoing its final manufacturing step—brazing operations expected to complete within days.

Additional components reaching manufacturing completion:

• Three complete sets of high-pressure turbine blades – Cast, machined, ground, and EDM processed with wire-locking features and full NDT (Non-Destructive Testing) validation
• Low-pressure turbine blades – Three engine sets cast and heat-treated, awaiting final machining and fir-tree grinding operations
• High-speed bearings – Custom-manufactured split bearings designed for the highest rotational speeds in the aircraft, featuring precision cages and rolling elements

A critical aspect of the prototype manufacturing process involves identifying and eliminating design features that create manufacturing difficulties or cost penalties.

Case study: Intermediate stub shaft redesign

The original design featured slotted holes in the shaft to manage swirl in the secondary air system as flow transitioned from stationary to rotating components. These slots required hours of machining time due to tool size constraints, significantly driving up manufacturing costs.

The solution:

• Replaced slotted holes with a greater number of round holes
• Round holes can be simply drilled, dramatically reducing machining time
• Secondary air system adapted to accommodate the design change
• Production-intent design captured and incorporated into test engine components
• This iterative improvement process ensures that prototype parts represent production reality as closely as possible, avoiding costly redesigns after initial testing phases.

To facilitate comprehensive monitoring during initial test runs, several engine cases are being manufactured using advanced 3D printing technology.

Key 3D printed components in production:

• Updated combustor case – Incorporates latest fuel injection system, combustion liner, and extensive instrumentation bosses for monitoring
• Interduct casing – Channels flow from power gas generator to power turbine
• Aluminum front casings – Form the smooth bell mouth inlet and house the accessory gearbox (drives oil pump, fuel pump, and auxiliary systems)

These printed components allow for rapid iteration and provide mounting points for the extensive instrumentation required to understand engine behaviour during critical early testing phases.

Running a jet engine for the first time—particularly in partial build configurations—presents significant challenges that extend far beyond the engine itself.

Test facility requirements being addressed:

Acoustic management:

• Custom acoustic enclosure design
• Exhaust treatment system to manage jet plume noise
• Initial gas generator operation (essentially a turbojet without power turbine) will be extremely loud
• Noise levels become more manageable once power turbine is installed and absorbing energy

Operational flexibility:

• Adaptable mounting systems for different engine configurations
• Instrumentation infrastructure for comprehensive data collection
• Variable operating protocols for different test phases
• 10,000-liter jet fuel storage tank now operational for extended endurance testing

The test cell fit-out begins in earnest next week, with all infrastructure coming together in parallel with final engine assembly preparations.

Before attempting first ignition on the complete GT50 engine, extensive combustion testing is being conducted in a dedicated test facility that has been significantly upgraded.

Current combustion development focus:

• Fuel system validation – Testing with actual production-specification fuel nozzles and high-pressure fuel systems
• Combustion parameter calibration – Establishing optimal settings for reliable first ignition and stable ground idle
• Component optimisation – Fine-tuning hole patterns in combustion liner, nozzle sizing, fuel injection pressures, and swirler geometry
• Risk mitigation – Proving combustion characteristics in benign environment before committing the prototype engine

Parameters validated in this test rig will be programmed into the GT50 control system, significantly reducing the risk of damage during those critical first moments when the prototype engine lights for the first time.

While engine development takes center stage, parallel progress continues on the HX50 helicopter platform, particularly in the area of crew seat safety and comfort.

Manufacturing process maturation:

• Carbon bucket tooling refined through multiple iterations
• Cure consistency and quality control established
• Representative carbon bucket tool producing consistent rear skins
• Pre-treated foam cores with film adhesive ready for carbon wrapping
• Closed-tool curing process validated

Comfort engineering achievements:

• Extensive ergonomic trials to optimize seat angle, back angle, and lumbar support
• Anatomically correct foam density mapping and thickness variations
• Aerospace-grade carbon-loaded foams meeting flame retardancy and toxicity requirements
• Precision-machined foam prototypes validated through user trials
• Production trim strategy developed using bonded leather

First prototype results:

• First complete carbon seat bucket with anatomically correct foam recently completed
• Salvage groove details incorporated for proper trim attachment
• Production-specification leather color options being evaluated
• Upper cushion aesthetics still being refined
• Metallic seat legs machined from high-performance aerospace alloy (production versions will use investment casting)

The seat suspension system, energy absorbers, and floor attachment mechanisms are all progressing through development, with 12 test units planned for structural and crash testing validation.

The composites team has made substantial progress on HX50's main rotor blade manufacturing, completing blade number six with comprehensive quality inspections.

Blade manufacturing process validation:

Completed operations on blade six:

• Full lamination schedule executed
• Curing process completed
• Tool extraction and geometric inspection
• Cut-up inspections at key cross-sections
• One-meter test sections extracted for structural testing

Quality assessment methods:

• Longitudinal blade sections cut to examine carbon laminate integrity
• Thick root-end sections evaluated for consolidation quality
• Transition zones to thinner airfoil sections inspected
• Consistency validation across multiple blade builds

Next development phases:

• Porosity detection and defect characterisation
• Non-destructive testing (NDT) process qualification
• Production volume inspection protocols
• High-volume manufacturing quality assurance procedures

The consistent quality being achieved demonstrates that the blade moulding process is stable and capable of producing flight-worthy components.

HX50's automotive-style climate control system, a rarity in light helicopters, is being validated using fuselage prototype number four as a dedicated test platform.

Climate control validation approach:

• Installing floor structures and full door/enclosure systems in test fuselage
• Mounting complete evaporator and condenser assemblies
• Integrating all air handling equipment with comprehensive instrumentation
• Testing at Mira climate chamber across full operational temperature range
• Validating heating, cooling, and ventilation performance before integration into Gen2 production fuselage

This systematic approach ensures the climate control system performs adequately across all environmental conditions HX50 will encounter in service, avoiding costly retrofits after deep integration into production aircraft.