The F‐16 fighter uses a form of hydrazine (H‐70, 30% diluted by water) to power its emergency power unit (EPU), as shown below. Hydrazine is corrosive, toxic, and highly flammable, which requires ground crews to have special handling protection, including self contained atmospheric protective ensemble suits. With the advent of green propellants, there is the opportunity to significantly reduce environmental concerns, increase safety, reduce ground time to return a fighter to flight, decrease the amount of time to investigate aircraft mishaps, virtually eliminate the amount of ground support, and decrease personnel training for multiple weapon systems.
The National Aeronautics and Space Administration (NASA) currently uses hydrazine as the propellant for their auxiliary power units (APUs) that gimbal solid rocket nozzles. In November 2014 Marshall Space Flight Center demonstrated the feasibility of using the green propellant AF‐M315EM with the existing hydrazine catalyst material on an F‐16 EPU gas generator. NASA and Penn State University later teamed together under a SERDP awarded scope (WP18‐1661) to demonstrate microwave solid‐ state ignition without the use of a catalyst. NASA was also funded by the Defense Logistics Agency in 2019 to conduct material compatibility of the green propellants with F‐16 hydrazine tanks. Further testing of the EPU assembly would demonstrate significant cost savings and minimize the impact of retrofit options available to the NASA APU and/or United State Air Force EPU applications.
Compared to the current use of the toxic hydrazine fuel, the green propellant will result in reduced environmental impacts and associated costs:
- Reduced potential of harmful worker exposure and health screening costs. Also, a reduction of support equipment necessary to sustain the new fuel compared to H‐70.
- Labor for inspection and maintenance of per protective equipment and propellant trailer.
- Training related to occupational health requirements.
- Hydrazine response team training/monitoring eliminated.
- Shipping costs for tanks and hydrazine, and disposal costs.
- Eliminate the need for monitoring the number of hydrazine runs and fuel consumed per month.