http://en.wikipedia.org/wiki/Safety_wire http://www.avweb.com/news/maint/191176-1.html Just google this to read it all as a PDF AC 43.13-1B <http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99C827DB9BAAC81B86256B4500596C4E?OpenDocument>