by Marc Mullis

Throughout the history of mankind individuals have come up with great ideas and inventions that for whatever reasons did not fit a timeline that would make them a success. Leonardo da Vinci invented the helicopter, yet it would be hundreds of years before the machine became viable. Benjamin Franklin discovered electricity, but it was decades before the infrastructure was in place to make its use plausible.

Such was the case with the idea of a young Paul Hajduk in the early 1960s. Today, Paul is a pilot with over forty years of experience, having flown everything from gliders to DC-3s. By trade, he was a spray pilot having started in the agricultural aviation industry in 1958. From his first season until the mid-1960s, he flew for various contractors around the world. From 1964 until 1966 Hajduk flew for Maritime Air Service, contracted to combat forest fires in the Canadian Province of New Brunswick. It was here that he was first introduced to the S2-R Thrush aircraft. He was impressed with the handling characteristics and capabilities of the relatively new aircraft.

It was on one of his many fire-fighting missions that Paul first conceived the idea of utilizing the numerous water resources of the province to fight the fires. There was a lake less than a mile from the fire he was working yet he was flying twenty miles to a tanker base to reload. If he were flying a float-equipped aircraft with scooping capabilities, he could increase his productivity from three loads an hour to thirty loads an hour, an increase of a thousand percent.

After his contract with Maritime Air Service expired, Paul decided to start his own company. In late 1966 he founded Modern Air Spray Ltd. His fleet of aircraft grew to include Piper Pawnees, Cessna C-188s, Douglas DC-3s and the dependable Ayres Thrush. For nearly two decades, Hajduk’s company was very prosperous. However, throughout this period of time he could not let go of the idea of a water scooping ag-plane for aerial firefighting. From his experience in Eastern Canada, he knew the idea would work.

A sudden downturn of the economy during the early 1980s forced Paul to make some tough decisions. The slump had resulted in a significant decrease in aerial application services yet he saw that the use of aircraft in fighting forest fires had seen a tremendous amount of growth. He decided to sell Modern Air Spray with its fleet of equipment and pursue his twenty-year dream of creating a self-contained, water-scooping system for an ag-type aircraft. The Ayres Thrush would be his aircraft of choice.

In 1983 Paul founded Terr-Mar Aviation with the set goal to effectively produce an affordable, practical and highly effective aerial fire-fighting alternative. His ideas were to contain all of the technical, performance and production characteristics now found in present day water-scooping air-tankers. After two years of intense research, engineering and trial and error, the first prototype of the Sea Thrush took form in a piston-engine version of the Ayres Thrush mounted on straight EDO 4500 floats. In mid-1985 the Sea Thrush made its first test flight/scooping run. The Terr-Mar-designed hydraulic scooping probe and the drop door performed flawlessly. After several flights, it became apparent that the 600 horsepower aircraft was grossly underpowered for the mission at hand. His idea was sound, but the practical application needed more development.

Paul knew that in order for the final product to be marketable it would have to be on amphibious floats. These would add more weight and further aggravate the lack of power from the Pratt and Whitney R-1340. Paul returned to the drawing board facing the reality that he needed to acquire a more powerful engine.

By 1987 the Turbo Sea Thrush was ready for its first flight. The airframe had been mated to a set of Wipline 6000 amphibious floats and the more powerful Pratt and Whitney PT6A-34 turbine engine. Now the aircraft could land at conventional tanker bases and the lighter and more powerful turbine engine solved the performance problem. Standard single-hull scooping tankers of the day had always faced a serious safety concern. If they had an emergency during the actual scooping operation they were unable to jettison their load. The Sea Thrush solved this concern and could easily get rid of its load on or off the water. The product was ready to be marketed.

Paul teamed up with John Goodwin of Custom Farm Service in Stanfield, Arizona to help introduce the Sea Thrush to the United States Department of Interior that could potentially become his largest customer. John already had a working relationship with administrative types in the various agencies that contracted for firefighting aircraft. He was also quite the innovator, having been involved in the development of several aerial application aircraft systems that included the original Satloc GPS guidance system.

John was able to arrange for a demonstration of the Sea Thrush in front of several Department of Interior administrators. The event took place on Lake Pleasant, which lies just north of metropolitan Phoenix. All in attendance at the demonstration agreed that the Sea Thrush performed flawlessly and they were impressed with its productivity. At the time, the Single Engine Air Tanker (SEAT) program had not been completely accepted. Instead, firefighting agencies were leaning toward adding to the growing number of Heavy Air-Tankers (HATs) already under contract. None of the agency personal would commit any funds toward further development of the Sea Thrush.

From lack of funding and several other non-industry reasons, the Sea Thrush program slowly slid into the shadows and the airframe was placed back on wheels and returned to service as an ag-plane.
Was this a good idea at a not so good time? Perhaps, but good ideas do not go away and recently International Aeroproducts Ltd. of British Columbia, Canada has mated the 660 Thrush to a set of Wipline 8000 amphibious floats and is powered by the PT6A-67. Maybe the time is right for Paul Hajduk’s idea to become a reality.