Aviation Safety Letter 2/2004
By Robert Laporte, Civil Aviation Safety Inspector, System Safety, Ontario Region
Though this article is meant to inform floatplane-fuelling operations of the safe and recommended practices, the information presented is applicable to all overwing fuelling operations. The term overwing fuelling is applied to fuelling operations using conventional hand-held and controlled fuel nozzles.
Aviation fuels generate an electrostatic charge when passing through filters, pumps, piping, and hoses. This charge, if not dissipated, is a potential ignition source for fuel vapours and therefore a serious fire hazard. The accepted method for neutralizing this charge is by bonding the aircraft to the fuelling system.
Bonding is the process of connecting two or more conductive objects with a conductor. Normally, a braided conductive cable with a clamp, jack, plug or clip is attached to the aircraft at one end, and to the fuel system at the other end to accomplish this bonding.
Many float operators wrongly believe that floatplanes in water are grounded and do not require bonding. National Fire Prevention Association (NFPA) studies have determined that grounding (the process of connecting conductive objects to the ground) is no longer required because it does not prevent sparking at the fuel surface. Bonding is the recommended method of controlling static electricity during fuelling. (Reference NFPA 407)
All aircraft, including floatplanes and the fuelling equipment through which fuel passes, require bonding. Companies with an Air Operator Certificate (AOC) are mandated by their company Operations Manual (OM) to bond their aircraft during fuelling. The bonding cable should be connected to designated airframe points or to clean, unpainted surfaces of the aircraft prior to opening the fuel cap. This ensures that the fuelling equipment and the aircraft are at the same electrical potential and thereby dissipate and neutralize any charges present and any charges generated during the fuelling process.
Aircraft should be bonded as per the following sequence:
Attach the bonding cable to the aircraft.
Attach the fuel nozzle bonding cable to the aircraft prior to removing the fuel cap. If the nozzle does not have a bonding cable, touch the fuel cap with the nozzle prior to removing the fuel cap. During fuelling, the nozzle should be in continuous contact with the filler neck to neutralize the build-up of electrostatic charges.
When fuel transfer is complete, remove the nozzle.
Replace the fuel cap.
Disconnect the fuel nozzle bonding cable if applicable.
Stow the fuel hose.
- Disconnect and stow the bonding cable.
Conductive fuel hoses are also required to neutralize any charges built up by the flow of fuel inside the hose. The conductive fuel hose is in addition to the bonding cable and is not meant to replace the bonding cable or to achieve the required bonding.
Those involved in aircraft fuelling require training and shall wear clothing of natural fabrics or fabrics that do not generate static electricity. Companies handling aviation fuels are also required to have an emergency response plan to deal with fuel spills and fires.
Fuelling is prohibited if thunderstorms are in the immediate vicinity. Fuelling operations shall be suspended and bonding cables removed if lightning is observed within 8 km of the aerodrome.
If aircraft battery power is required during fuelling, the aircraft's external lighting, strobe lights and rotating beacon should be turned off.
Air Operators may have procedures for fuelling with passengers on board. Because of its lower flash point and higher volatility, passengers should always be disembarked when fuelling avgas.
When conducting fuelling operations, a 3-m safety zone should be established around the filling and venting points. Only essential personnel should be allowed in the safety zone. Fire extinguishers should be strategically located and clearly marked. Vehicles not involved with fuelling should be prohibited within 15 m of the aircraft.
The following are prohibited inside the 3-m fuelling safety zone:
- Open flames
- Use of radios
- Electronic devices such as cell phones, pagers, CD players, etc.
- The operation of electrical switches
- Use of photographic flash equipment (bulbs or electronic)
- Motorized vehicles
- Any activities that could produce a spark
For more information on fuelling, consult the Canadian Standards Association (CSA) B836-00, at The Canadian Standard for Storage, Handling, and Dispensing of Aviation Fuels at Aerodromes, at http://www.csa.ca/.
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