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bonding vs grounding

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The only thing I can think of was on the 'other' forum. Here it is/was:

cap, as long as the helicopter and the drum are electrically bonded, there is no requirement to ground the helicopter or the drum, accordring to the standard reference on this subject, NFPA 407 (presumably no relation to our own 407 driver). NFPA is the National Fire Protection Association, recognized as the North American authority on fire protection.


NFPA 407 App A A-3-4: "Grounding during aircraft fueling or refueler loading is no longer required because: (a) It does not prevent sparking at the fuel surface (see NFPA 77, Recommended Practice on Static Electricity). (B) It is not required by NFPA 77, Recommended Practice on Static Electricity. © The static wire might not be able to conduct the current in the event of an electrical fault in the ground support equipment connected to the aircraft and could constitute an ignition source if the wire fuses"


Electrical charge differentials are equalized through bonding the different parts of the system together, not through grounding.


Two of the major causes of electrical charge during fuelling:


a) The passage of fuel through filters and hoses, but especially through filters


NFPA 407 Appendix A. A-3-4: "Hydrocarbon fuels, such as aviation gasoline and JET A, generate electrostatic charge when passing through the pumps, filters and piping of a fuel transfer system. (The primary electrostatic generator is the filter/separator that increases the level of charge on a fuel by a factor of 100 or more as compared with pipe flow.) "


B) Electrical faults in pumps causing voltage to be applied to the fuelling hose and nozzle


Also, NFPA 407 includes a warning "Ordinary plastic funnels or other non-conducting materials can increase static generation. The use of chamois as a filter is extremely hazardous".


The recent back page article "Fuel Drum Etiquette" did not explain these points well enough, and I intend to publish the above information in an upcoming issue. Hope it helps.

Editing here. Looking back at that topic, it may be useful to read the whole thing. Here's the link. http://www.canadianaviation.com/private-cg...t=000730#000006

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