The H2 EM Aero Engine is a field governed, ammonia fuelled hydrogen combustion architecture designed for piston propeller aircraft. It eliminates the storage problem that has made hydrogen impractical for general aviation by cracking ammonia on demand and producing only the hydrogen required for the next combustion cycle. No hydrogen is ever stored on board. The only fuel carried is liquid ammonia in a standard aviation rated pressure vessel at modest pressure and ambient temperature. This allows the system to retrofit directly into existing Lycoming and Continental engine classes without structural modification or specialist airport infrastructure.

The architecture uses the Type I A and D A cracking module, a microwave driven sub atmospheric cavity that converts ammonia into hydrogen and nitrogen. The nitrogen is inert and is vented overboard. The hydrogen is delivered immediately to the injector manifold. The total hydrogen inventory on board is only a few tens of millilitres at near ambient pressure, which is several orders of magnitude below the threshold that defines a significant hazard in conventional hydrogen aircraft concepts. Exhaust chemistry is water vapour and nitrogen only.

The engine uses electromagnetic gated combustion. Instead of relying on a spark plug to ignite a flammable mixture anywhere in the chamber, the system creates an authorised ignition zone defined by a shaped electromagnetic field. Ignition can occur only inside this zone. This reduces unintended ignition probability by several orders of magnitude and allows the combustion event to be shaped, stabilised, and governed in real time. The DIGSP supervisory layer manages mixture, ignition timing, altitude compensation, and fault graceful degradation at one hundred hertz.

The retrofit kit replaces the cylinder heads with EM enabled heads containing confinement coils, a plasma ignition module, and field shaping inserts. The cracking module is installed firewall forward. The ammonia tank is installed aft of the firewall in the existing fuel bay. The hydrogen transfer line never crosses the firewall. A hydrogen radar system monitors all hydrogen handling zones using radio frequency dielectric shift sensing. An ammonia slip detector monitors the tank bay and firewall penetration. Any confirmed leak triggers an ordered shutdown sequence.

Performance targets include eight to fifteen percent higher brake thermal efficiency than AVGAS, forty to seventy percent lower nitrogen oxide emissions, and zero carbon dioxide emissions. Power derating at low altitude is expected to be five to ten percent due to parasitic electromagnetic load, but this is recovered at cruise altitude where field strength requirements fall. At cruise, net power is expected to be equal to or greater than AVGAS operation. Fuel cost is expected to be dramatically lower because ammonia is produced from seawater and renewable electricity at coastal H2EM plants.

The H2 EM Aero Engine is designed for Supplemental Type Certificate retrofit on the most common general aviation engines. Installation requires no changes to the crankcase, camshaft, or airframe structure. The system adds between thirty five and ninety kilograms depending on configuration and cylinder count. It offers a practical, certifiable, zero carbon propulsion pathway for the global piston aircraft fleet without requiring new airframes, new airports, or new fuel logistics.