W31_3

W31 3
http://aeroelectric.com/Pictures/Breakers/W31_3.jpg
". . . where robustness of the braided copper jumper wire is not meeting design goals. If the "added insulator" is not present, jumper failure causes load current to flow through the contact-spreading spring. IF the switch is used in a high current application (prop de-ice, pitot heat) then the spring smokes and folks get upset."
"The "FIX" didn't stop the wire from breaking, it only kept the secondary event from occurring. So instead of getting a broken wire followed by smoke, you only get a dead accessory. Now, I suppose the next shoe to drop will insist that some light or warning be included.
Yeah, put a paragraph in the flight manual asking the pilot to keep an eye on the ammeter lest a broken wire sneak past without notice . . . but at least we don't put smoke in the cockpit."
Note:
Here is an alternative breaker switch and pics of braid failure:
http://www.williamsairpower.com/pdf/switches.pdf
Y9-07-31