Building tomorrow’s firefighting tankers

Key to the U.S. Forest Service’s strategy for containing and quenching the wildfires that raged across New Mexico in May were the scores of aircraft that soared over the blazes, dumping thousands of liters of retardant and water.

Many of these aircraft have been in service for decades, and with wildfires across the world projected to burn longer and more intensely compared to past decades, the U.S. Forest Service and its contractors need to expand their fleets.

Enter ST Engineering of Singapore, which in February announced a contract to convert a former Boeing 757 passenger airliner into a firefighting tanker for Galactic Holdings, an Arkansas fire suppression startup founded in 2020. With a planned capacity of 26,000 liters, the 757 would carry more retardant than the C-130s on loan from the U.S. Air Force — which hold 11,000 liters — but less than the DC-10s that carry roughly 45,000 liters, about half the capacity of a public swimming pool.

Being newer than the DC-10s and other converted planes, “we are thinking that 757 will give you more fuel efficiency, better kind of capacity as well as more optimal operations,” including the ability for pilots to fly at lower altitudes over fires, says Leon Tan, ST Engineering’s program manager for the 757 conversion.

Also, the 757 was designed to take off from shorter runways — all the better for deploying from small airports near wildfires that break out in rural areas, he says.

The tanker is scheduled to be delivered to Galactic in 2024, so plans call for finalizing the design later this year, then beginning modification at one of ST Engineering’s U.S. facilities; the company has facilities in Alabama, Florida and Texas.

Technicians will begin by tearing out the 200 seats to make room for one of two 13,000-liter tanks that would hold the retardant. The other tank would go in the cargo hold below. The aircraft’s windows must also be removed and the holes plugged with cover plates. ST plans to use plates instead of sealing the windows so its technicians can take advantage of the openings as access points to the upper tank when maintenance is needed, Tan says.

In parallel, ST Engineering will work with FAA to determine what ground and flight tests would be required for the design to earn the supplemental type certification that verifies the modifications meet FAA’s standards for airworthiness and do not significantly change the performance of the aircraft.

“There might be some test requirements, but we are trying to keep inside the envelope of the passenger aircraft in the sense that you’ll still be doing the same kind of flight maneuvers,” Tan says.

If approved, this design would be used as a blueprint for future 757s ST Engineering converts for Galactic Holdings. Tan says the terms of the contract specify between 10 and 12 aircraft in total, “depending on the needs.” 

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Aircraft Design

About Cat Hofacker

Cat helps guide our coverage, keeps production of the magazine on schedule and copy edits all articles. She became associate editor in 2021 after two years as our staff reporter. Cat joined us in 2019 after covering the 2018 congressional midterm elections as an intern for USA Today.

Building tomorrow’s firefighting tankers