PURPOSE: To electrically integrate the whole of an aircraft, and thereby prevent the occurrence of electrostatic sparks by installing earthing bus bars over the full length of the inside of a fuselage, and thereby connecting all metallic and semiconductive parts to the earthing bus bars with bonding cables.

CONSTITUTION: The voltage of extra high voltage current (positive) of ten to twenty hundreds of millions of volts is charged to an ionized layer which is electrically semiconductive, and negative voltage is charged to the earth, thereby there happens leakage discharge caused by potential difference while breaking through the insulating band of air in a troposphere. The troposphere is mostly composed of nitrogen constituent high in insulating properties, and also includes a group of clouds and the like containing moisture low in insulating properties, so that there exist violent irregularities in voltage, namely, violent change in voltage exists in the troposphere. When an aircraft flying in the aforesaid space is subjected to change in voltage as mentioned above, there is thereby a fear that electrostatic sparks may be emitted. In that place, earthing bus bars 1 are installed over the whole inside of a fuselage, all metallic and semiconductive parts in the inside of the aircraft are then connected to the earthing bus bars 1 with bonding cables 2, so that the whole of the aircraft is thereby electrically integrated.