The Cessna 120-140 Association Forum

I am routing a new 4GA wire (M22759/16-4-9) to the battery and I am trying to figure out how to protect the cable during its travels through the bulkheads.
Should I use something like AN931 Elastic Grommets? Or some kind of wrap?

Here's the cable going through the gearbox.

I would say yes Chris, there are supposed to be AN931 grommets in those holes. Check the 120/140 parts book in the documents section of the main web page. Figure 18 does show the AN 931-7-11 grommet used in several locations in the bulkheads. My 140A uses the same to protect the battery cable running through the bulkheads.

Mike

i have grommets and the cable is wrapped in a plastic sheath of some kind.

For something like that I prefer "tracks". Or Grommet edge seal.
https://www.aircraftspruce.com/catalog/ ... kkey=21018

Basically a thin plastic serrated edge protector. Radio shops use it all the time, I feel it protects long term better than grommets. Also.......you don't need as large of a hole and usually easier to install with the wire in place.

V529 wrote: ↑Mon Dec 08, 2025 7:40 am For something like that I prefer "tracks". Or Grommet edge seal.
https://www.aircraftspruce.com/catalog/ ... kkey=21018

Basically a thin plastic serrated edge protector. Radio shops use it all the time, I feel it protects long term better than grommets. Also.......you don't need as large of a hole and usually easier to install with the wire in place.

Good point Victor, I forgot about those. It’s a shame those probably weren’t available when these aircraft were being manufactured many moons ago.

Here's a better pic of the stuff at the shop. Set of side cutters and half dollar for reference.
Personally I prefer the clear plastic as opposed to the green metal band,
The differenct is the clear plastic is easier to install.
The green metal units are "sturdier" and will hold up better for more severe conditions.