Oshkosh, Wisconsin – Piper Aircraft, Inc. has unveiled the Seminole DX, a diesel-powered evolution of its renowned PA-44 Seminole twin, powered by DeltaHawk’s FAA-certified DHK4A180 heavy fuel engine. The announcement was made during the 2025 edition of EAA AirVenture Oshkosh, where the orderbook officially opened for position reservations.
The new Seminole DX is the product of a strategic collaboration between Piper and DeltaHawk, launched in early 2024. It integrates DeltaHawk’s 180-horsepower, turbocharged, liquid-cooled, compression ignition engine—delivering turbine-like performance with up to 40% greater fuel efficiency compared to conventional avgas piston engines.
“We’ve listened to the market, and it’s clear: there’s demand for a reliable, cost-effective, heavy fuel, multi-engine training aircraft,” said John Calcagno, President and CEO of Piper Aircraft. “The Seminole DX answers that call and fills a clear void. Based on the global response since announcing our MOU last year, we expect sustained demand of 25 to 40 aircraft annually over the next decade.”
Modern Power for Tomorrow’s Training Fleet
Certified for use with Jet A and Jet A-1 fuels—with Sustainable Aviation Fuel (SAF) approval pending—the DHK4A180 engine offers notable maintenance and operational advantages due to its fewer moving parts. The Seminole DX is being integrated into Piper’s production line via a Piper-owned STC and includes DeltaHawk’s firewall-forward kits with counter-rotating engines and three-blade, full-feather propellers.
An advanced climate control system, leveraging the engine’s liquid cooling, will deliver improved cabin comfort across all operating environments—further enhancing the aircraft’s suitability for high-demand flight training.
Performance improvements over the standard Seminole include:
- 35% reduction in fuel burn
- 32% increase in single-engine climb rate
- 70% higher single-engine absolute ceiling
(Preliminary figures pending certification testing)
“Installing our certified DHK engine into the legendary Seminole is a natural fit,” said Christopher Ruud, CEO of DeltaHawk Engines. “This platform offers the lowest cost of ownership and the safest, most straightforward twin-engine training experience in the industry. We see this as more than just a 20-year engine supply agreement—it’s a step toward widespread innovation and environmental sustainability in general aviation.”
Looking Ahead
Certification flight testing is set to begin in November 2025, with FAA certification targeted for Q3 2026. Approvals from Transport Canada, EASA, and India’s DGCA will follow. Deliveries of the 2027 model year Seminole DX are expected to begin by late 2026 or early 2027.
Beyond the PA-44 platform, Piper and DeltaHawk are also actively exploring diesel engine applications for the PA-28 Archer and PA-46 M-Class aircraft, reinforcing a growing partnership aimed at redefining general aviation powerplants.
SOURCE AND IMAGE©: DELTAHAWK
