Piper says it’s signed a deal with Wisconsin-based DeltaHawk to explore installing the Jet A and SAF-burning engines in its iconic piston twin, the PA-44 Seminole. “We are constantly seeking opportunities to innovate and advance our aircraft offerings,” said Piper VP of Engineering and Manufacturing Marc Ouellet. “Working with DeltaHawk on this project aligns with our mission to explore cutting-edge technologies that can deliver significant benefits to our customers and the industry as a whole.” DeltaHawk will get an STC to install the 180-horsepower four-cylinder engines on the Seminole. The STC will cover new aircraft and retrofits. “Our advanced Diesel engine technology has been developed to meet the evolving needs of the aviation industry, and we see tremendous potential in integrating it into Piper’s PA-44 Seminole,” said DeltaHawk CEO Christopher Ruud.

Larry Anglisano
Larry Anglisano is a regular AVweb contributor and the Editor in Chief of sister publication Aviation Consumer magazine. He's an active land, sea and glider pilot, and has over 30 years experience as an avionics tech.


  1. Apparently certified but no production certificate yet. If fuel burn of 0.36lb/hp/hr and weight of 1.5lb/hp for the high hp version are accurate, competitive pricing should make it a winner.

      • No, i meant the Janitrol heater in the Seminole for cabin heat- uses avgas for heating the cabin – can it use the same diesel fuel?

    • Choosing SAF or Jet-A is an operational issue, driven by spot availability and price. The engine is happy with either fuel.

  2. That will never work, Orville! Oh, never mind. It works in millions of cars. And THERE is another great benefit, no worry about the heater killing you with CO.

  3. $60k for the experimental version, vs $35k for an overhauled Lycoming engine, or $70k for a new Lycoming. Seems a reasonable deal if they stick to it.

  4. Been reading about DeltaHawk since before I got my PPL. I think I saw them at OshKosh in 2006 ? Introducing common automotive tech to the aviation world is a life long endeavor. I hope this works out for them. Does DeltaHawk offer a performance / price advantage over the diesels Diamond uses (Austro) ?

    • Im not sure what you mean by “Just go fly a Diamond”

      Diesels are all heavier. This is why twins are a popular application. There’s a reasonable belief that making a new plane with a new engine is too big a risk.

      I believe there’s a market for a diesel single if buyers would give up on the idea that they need the empty back seat. While some of our most memorable flights have been with passengers in back, they were very few unless you count dogs.

      The diesel DA40 or DA20 sounds attractive if they would “simply” update the design around the new engines. The weight difference could likely be nullified. Of course, it’s not only a risk, but a HUGE time and money investment to certify a plane even if it’s 95% the same as an existing one that’s twice as safe as anything else certified.

      It’s not just crazy, it’s stupid.

      • All of the Diamonds I have flown that have diesels fly very heavy. You can feel the heaviness of the diesels. It’s very prominent.

        • Well, you can feel a heavier load. Still, a heavy Diamond flies nicer than most other planes IMO.

          Center stick and control rods for the win. 😃

          I haven’t flown any of their twins, but the Lycoming DA42 and DA 40 have more HP than the diesel versions which makes a difference.

          I also noted a difference going from the MT to the hartzell prop. Weight on the nose might be more noticeable, maybe?

          • I had a DA40, IO 360, extended tanks, G1000, WAAS, synthetic vision, GFC 700. Over 1,200 hrs. Handling, visibility, pure joy of flying a center stick with push rods and torque tubes, you just couldn’t beat it. I loved the airplane. The avionics and autopilot made it a true cross country machine albeit a bit of a slow one which really wasn’t all that bad. Approaches to minimums were and absolute breeze. I really can’t say a bad thing about the airplane. Best bang for the buck I have ever seen. Then they put the diesel on it and in my opinion in one swell swoop destroyed a beautiful flying machine. Weight does matter. Especially in handling.
            The truth of the matter is my Aerostar has many of the same attributes that made the DA40 such a fine airplane. My Aerostar is a little bit faster, however, the avionics don’t compare to what I had in the DA40. It’s all a trade off. I needed more speed. That being said, I think you would be shocked if after flying a DA40 for awhile you would immediately see the similarities in the Aerostar. Both incredible airplanes. I didn’t like the DA42. The diesels greatly affected handling.