Piper Announces New Seminole DX Powered by DeltaHawk

Piper Aircraft announced at Oshkosh 2025 the launch of the new Piper Seminole DX, a diesel-powered PA-44 Seminole fitted with DeltaHawk's FAA-certified DHK4A180 engine. This engine provides 180 horsepower and incorporates heavy fuel compression ignition. The Seminole DX is the outcome of a successful partnership between Piper and DeltaHawk, which began in early 2024.

The liquid-cooled, 180HP turbocharged DeltaHawk engine delivers turbine-level performance with 40% greater fuel efficiency compared to traditional reciprocating avgas engines. This engine also offers a substantial reduction in ownership costs due to its fewer moving parts. It is approved for use with JET A and JET A-1 fuels, with approval for Sustainable Aviation Fuel (SAF) currently pending. Piper will employ a Piper-owned Supplemental Type Certificate (STC) to integrate DeltaHawk’s firewall-forward kits into the Seminole production line. The kit features counter-rotating DeltaHawk engines and three-blade, full-feather propellers. Furthermore, the aircraft will be equipped with an advanced cabin temperature control system that leverages the engine's liquid cooling, ensuring a comfortable flight experience across various conditions.

“The market has been heard, loud and clear, regarding the need for a reliable, cost-effective, heavy fuel, multi-engine training platform,” said John Calcagno, President and CEO of Piper Aircraft, Inc. “The new Seminole DX fills that market void perfectly. Based on interest received since our MOU announcement last year, we anticipate global market demand for the Seminole DX to be between 25 to 40 aircraft per year over the next 10 years. The DeltaHawk team has been a pleasure to work with over the past 16 months as they epitomise quality and customer focus. Future collaborations are in process as well.”

A 20-year Long Term Supply Agreement (LTSA) has appointed DeltaHawk as the exclusive supplier of heavy fuel, piston engines for the Piper Seminole. Certification flight testing is scheduled to commence in November 2025, with FAA certification projected for the third quarter of 2026. Subsequent certifications from Transport Canada, EASA, and India’s DGCA are also anticipated. Deliveries of the 2027 model year Seminole DX aircraft are expected to start in late 2026 or early 2027.

“The installation of our certified DHK engine in the legendary Piper Seminole is a perfect match with our industry-unique features to provide the lowest cost of ownership and the simplest and safest multi-engine training platform ever,” said Christopher Ruud, Chief Executive Officer of DeltaHawk Engines. “Just as important, we see this new 20-year agreement not just in terms of engines, but also as a wonderful step by Piper, utilising DeltaHawk’s powerful innovation, while creating environmental sustainability for general aviation worldwide.”

The Seminole DX provides substantial performance improvements compared to the existing PA-44 Seminole, featuring a 35% reduction in fuel consumption, a 32% increase in single-engine climb rate, and a 70% higher single-engine absolute ceiling. Piper and DeltaHawk are investigating additional engine applications for the PA-28 Archer and PA-46 M-Class platforms, thereby enhancing their partnership for future innovations.

DeltaHawk Engines, located in Racine, Wisconsin, is a privately owned company specialising in the production of advanced-design, FAA-certified jet-fueled piston engines for general aviation aircraft and hybrid power systems. The company possesses numerous patents for its innovative engine designs. DeltaHawk's team, comprising engineers, designers, manufacturing specialists, and certification experts, is dedicated to developing a new generation of groundbreaking piston engines.