Fire Caulk

[mattsmith]

Is it acceptable to use a plastic snap busing and fire caulking for the wirer's penetrating the firewall. I am building a 8 and were the planes call to go thru I don't think I can get a metal shield between the side skin and center of hole?

[carguy614]

Vans says the snap bushing and caulk with silicone method is OK. It is done that way on many certified planes as well, however, I find it a splendid place to upgrade. I used a cable clamp (Cable Safe) on my firewall passthroughs. Tight, and flame resistant, but also stabilizes the cable sheath to allow a predetermined amount of flex between your stationary firewall and moving engine. Very hard to achieve this without anchoring the cable sheath at the firewall.

YMMV,
Chris

[carguy614]

Sorry, misread your post. If you are using a passthrough for wiring, it is established practice to silicone a wiring bundle.

Regards,
Chris