This kind of bearing damage also occurs in the wheel bearings of streetcars (trams) and electric locomotives because the traction current returns through the rails. If the bearing was not designed for this service using metal or carbon brushes to bypass current or if the brushes went bad the current would destroy the bearing.
What you have is a high-tech version of a century old problem.
Skogsgurra, thanks for the tip that static electricity from a belt or fan blade could be the culprit. One of my stepbrothers was in a hekicopter transport unit in Vietnam and he would tell me about the he!!atiuos amount of static charge that builds up on a helicopter or airplane when it is flying. When hooking up a sling load to a helicopter the people with experience would throw the nylon ring onto the hook on the bottom of the helicopter and then throw the sling load hook onto the ring and jump off the sling load just before the load hook contacted the helicopter hook. Every newbie would reach up and grab the hook on the bottom of the helicopter with their hand, then his eyes would pop out, and then HE woudl go flying about 20 to 100 feet.
The Human Voltmeter Method never feels good.
Mike Cole, mc5w@earthlink.net
