B757 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Training / Qualification; Communication Breakdown; Confusion; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy
Chart Or Publication; Procedure; Company Policy
During the preflight inspection of our B757; and while passengers were loading; I noted that the fuel truck to aircraft grounding wire clamp was clamping the grounding wire to the aircraft grounding point; but was not attached to the grounding wire. The clamp had become disconnected from the grounding wire; so the fuel truck operator had simply clamped the plastic sheathed wire to the aircraft grounding point.Obviously; plastic is not an acceptable conductor for aircraft grounding. From my understanding of electricity and aircraft fueling; the reason we ground the aircraft to the fuel truck is to prevent potential voltage from building up during the flow of fuel into the aircraft (think static electricity). Thus; failure to ground the aircraft to the fuel truck could result in voltage build-up; then a spark; which could in turn; cause an explosion with fatal consequences. I immediately advised the fueler to stop fueling the aircraft and showed him the problem. He stated that he had found the clamp was disconnected when he got on shift; but did not know that the grounding wire was encased in a plastic. He thought that some trucks had two grounding wires; but he didn't know where the second one was. I asked him to get another fuel truck. He later advised me that he had found the second grounding wire (mounted at the fuel trunk's front bumper) and he had used that one instead. It appears that basic fueling safety procedures are either not being explained to some fueling personnel; or have been forgotten. I strongly suggest we revisit this subject with our contractors; and emphasize the importance of proper grounding to our pilots as well--our B757 was certainly not the first aircraft he had fueled that evening and it likely that more than a few pilots had failed to see this risk during their preflight inspections as well.
A B757 First Officer discovered a fuel truck plastic coated grounding wire; without a grounding clip attached to the aircraft ground point during fueling; but not properly grounding because plastic will conduct static electricity.