what is an "impedance type" bolt

[johnSchwaner]

I received an Engineering drawing for a helicopter part titled "Bolt, Self Retaining Impedance Type, Alloy Steel and CRES, 95 ksi."

Anyone know what impedance type means?

 

[Lcubed]

Impedance bolts have either spring-loaded balls, or a spring ring in a groove on the bolt shank, above the threads. These retaining elements extend beyond the diameter of the bolt and prevent it from sliding from the parts.

Impedance bolts are not positive-locking; they can be pressed out of the assembly, but only by overcoming the resistance, or impedance, of the retaining elements.
Regards,
Lcubed

 

[thruthefence]

"Calfax" fastener?

 

[johnSchwaner]

Thankyou. I had never heard of the term before.