Electrostatic Discharge (ESD) is defined as a transfer of electrostatic charge between objects at different potentials caused by direct contact or induced by electrostatic fields.
An electrostatic discharge from human contact can reach 35 kV. Many new microcircuits can be damaged or destroyed by as little as 20 volts.
Common events like the shock from touching a doorknob after walking across a carpet, touching a car door after sliding across the seat, or rubbing a balloon across hair and sticking it to the wall are all examples of ESD. These three examples require large amounts of voltage in order to be observed or felt; however, a minimal voltage buildup can easily cause damage to a microcircuit. Even if a microchip or circuit has not been destroyed by a voltage surge, it may not be readily apparent that any damage has occured until too late in the mission.
Taken from: Maintainer, Aviation Safety, Issue 4/2004, TP 3658E ISSN 0823-5538:
"But static electricity is everywhere and may have been present earlier this year when a maintenance crew was performing a tail rotor balancing event on a Bell 206B. The maintenance was necessary following the replacement of a tail rotor gearbox bearing and a search to try and rid the helicopter of a vibration in flight. The standard electronic tracking unit was being used and the accelerometer had been placed on the rear gearbox. The technicians were standing outside with the Strobex while the pilot adjusted power to obtain the various readings to meet tracking and balancing requirements. The electronic tracking unit had been placed on the rear seat and the wiring for the accelerometer passed through the left-hand access door, taped to the belly of the helicopter and onto the tail of the helicopter. The wire-harness stretched along the belly and near the fuel tank vent line. It was a dry, sunny winter day, and the two technicians were standing in the path of the moving air mass created by the rotating main rotor. While the pilot was maintaining power and rotor speed, a technician reached inside the helicopter and touched the electronic unit. At that moment, the fuel tank ruptured as the fuel it contained, approximately 15 gallons, exploded. The technician was thrown several feet away from the helicopter and the pilot felt the blast and was thrown against the cockpit windshield."
ESD Links:
Electrostatic Discharge Association
The ESD Guide
ESD Journal
Protect Your High-Speed Circuits from ESD Transients
EMI Filters with ESD Protection Reduce Interference in Cell Phones
The following links are excellent articles/Q&As/ESD information from Compliance Engineering Online.
Critical Factors in ESD Program Management
ESD Myths and Latency Controversy
An Overview of ESD Control Procedures and Materials
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