Many times to save time or a start cycle on a turbine engine, pilots and operators will perform hot refueling, or what is technically called Helicopter Rapid Refueling (HRR). The National Fire Protection Association (NFPA) publishes document 407 titled “Standard for Aircraft Fuel Servicing” which includes a section on HRR.
According to the NFPA only turbine engine helicopters fueled with Jet A or Jet A-1 fuels shall be permitted to be fueled while an onboard engine is operating. All sources of ignition must be located above the fuel inlet port(s), vents or tank openings. Ignition sources include engines, exhausts, APUs and combustion-type cabin heater exhausts.
Some additional NFPA requirements for HRR are:
- An FAA-licensed helicopter pilot shall be at the aircraft controls during the entire fuel servicing process.
- Passengers shall de-board to a safe location prior to rapid refueling operations.
- Passengers shall not board or de-board during rapid refueling operations.
- Only designated personnel, properly trained in rapid refueling operations, shall operate the equipment.
- All doors, windows, and access points allowing entry to the interior of the helicopter that are adjacent to, or in the immediate vicinity of, the fuel inlet ports shall be closed and shall remain closed during refueling operations.
- Fuel shall be dispensed into an open port from approved dead-man type nozzles, with a flow rate not to exceed 60 gpm or it shall be dispensed through close-coupled pressure fueling ports.
- When fuel is dispensed from fixed piping systems the hose cabinet shall not extend into the rotor space.
- A curb or other approved barrier shall be provided to restrict the fuel servicing vehicle from coming closer than 10 ft from any helicopter rotating components. If a curb or approved barrier cannot be provided, fuel servicing vehicles shall be kept 20 ft away from any helicopter rotating components and a trained person shall direct the fuel servicing vehicle’s approach and departure.
Even with these safety precautions I have talked to operators that will not hot refuel because of the increased risk.