What Are The Risks Involved In Refueling And Defueling Aircraft

Aircraft refueling and de-fueling often lead by attendant hazards which should be managed sufficiently for their mitigation to acceptable levels. The issues are same with tanker or fuel hydrant system. Pressure refueling is normal for business jets and multi-crew transport aircraft but nowadays gravity refueling are available as a backup system. Turbine engine aircraft is used by kerosene fuel has higher flash or ignition point than that of aviation gasoline. Aviation gasoline used by piston engine aircraft has a potential hazard.

The primary risk involves unintended ignition of fuel vapor which can occur by a single spark. Fuel vapor has a sufficient quality that creates a high risk of ignition may result from spillage arising from procedural errors, leaks, aircraft tank venting or failure of pressurized fuel lines or their couplings. A spark of sufficient intensity to ignite fuel vapor can result from the discharge of static energy created either from the movement of the fuel in the aircraft tank during the fuelling process or accumulation of surface of aircraft or vehicles.

During refueling or de-fueling fuel, the movement may lead to a static charge in building up in the fuel. If the charge is in high potential, it can cause sparking within the aircraft. The possibility of sparks inside the tank and the charge density in the fuel are not affected by bonding. The use of static dissipater additives in the fuel can contribute materially to the reducing risk involved.

Accumulation of a surface static charge may occur in either on aircraft bladder tank or in its fueling vehicle under any certain conditions. Electrical bonding must be used to eradicate this hazard. Coupling and uncoupling of hoses must not be undertaken unless electrical bonding is in place. Re-fueling should not take place during thunderstorms.

Electrical bonding

There must be a cable to link between the point or to clean unpainted metal surfaces on the chosen airframe. Bonding cables should be connected to the installation delivering the fuel with the aircraft or installation receiving the fuel. All connections should be made before filler caps are removed earlier to start fueling and then not broken until the fueling is completed and filer caps are replaced where it is appropriate.  Under no circumstances, either fueling vehicle or the aircraft is attached to a fuel hydrant pit.  Keep in mind that Fuel Hoses including “conductive” hoses are not suitable substitutes for dedicated clips and bonding wires.

Static dissipater additive

If turbine fuels do not contain a static dissipater, then it’s quite impossible to load wide-cut fuel. Wide-cut fuel is considered to be “involved” when it’s being supplied or when it’s already presented in the aircraft tanks. It is recommended that when wide-cut fuel has been used then the next two uplifts of fuel should be treated as wide-cut. A mixture of kerosene turbine and wide-cut fuels can result in the air-fuel mixture in the tank. The mixture is in the combustible range at common ambient temperatures during fueling.

PED use during refueling

PED or personal electronic device may create or induce a spark of sufficient intensity to ignite fuel vapor released during fueling but it is inaccessible under normal circumstances. The main concern is the proliferation of below specification mobile telephone batteries that have the potential to fail dangerously. It is unknown that whether such failure would be sufficient magnitude to ignite a fuel or the air mixture but the possibility still exists. It is recommended under any circumstances during refueling should be carefully considered and mitigated. It also appears that personal electronic devices close to or onboard modem aircraft can interfere with fuel gauges. Some navigation equipment may cause false fire warnings in cargo or baggage holds. Airport operators should prohibit the use of the personal electronic device on the apron area in the vicinity of refueling operations. Passengers boarding or disembarking an aircraft should be discouraged from using personal electronic devices.

Refueling on the passenger on broad

Aircraft operators should have their procedures for refueling including emergency evacuation and if refueling is permitted with the passenger on board then it should be appropriate with operations manual and Cabin Crew Manual. Crew stations and duties should be clearly defined with passenger communication. The procedure of emergency evacuation for passenger should be taken into account the availability of airbridge access or in-position ground steps in the selection of exits to be used. One of the flight crew should remain in the flight deck at least. There is a common situation that is often overlooked is where refueling commences after gate arrival but before all passengers have got off or started to get off. The crew busy with their routine post-shutdown procedures may not be aware that the doors have been opened and disembarkation started. An unexpected requirement to carry out an emergency evacuation might create difficulties.

Fire hazard during fueling and de-fueling

Due to the combustible nature of turbine engine fuel and AVGAS, the potential for fire while fueling and de-fueling aircraft must be addressed. Always fuel and de-fuel outside, not in a storage room that serves as an enclosed area for vapors to build up to a combustible level. Clothing worn during refueling personnel should be safe not promote any static electricity buildup, synthetics such as nylon should be avoided. Cotton can be a safe way of handling fuel.

De-fueling

This is an infrequent and special operation. The person involved including any flight crew should be careful to refer any necessary procedural documentation. Fuel removed from aircraft tanks never reused and must be offloaded into a dedicated de-fueling tanker.