On the other hand, I have seen many fuel lines and oil lines ending up being ground straps as well. The Aeroquip stainless braid will work for this for years in some cases, and for a few seconds in others. The failure mode involves open braid that is under a crossing braid, so it cannot be seen. If you have evidence of conduction like a black oxide on the braid where it is easy to see, there may be some parted strands against the hose liner. Build a new hose. It will eventually puncture the liner and produce a leak.

 

Grounding is a great big deal. Starters can draw over 100 amps. A high amperage strap from the battery to a starter mounting bolt is a good start. Many other hoses will be included in this same circuit. Anything from a bulkhead fitting on the fire wall will be at ground potential. So you have a number of parallel paths.

Solve for resistors in parallel.

The battery ground strap has to have the very lowest resistance of all of those paths, lest excessive sharing begin. So clean shiny contact surfaces, protected from corrosion.

 

Lynn E. Hanover

 

Bill,

 

From your description, your ground architecture sounds very similar to mine.  I have the forest of tabs bolted to the firewall with a brass bolt.  On the cabin side, the battery ground is connected to this bolt.  Everything else grounds to the forest of tabs.  On the engine side of the firewall, the engine ground is connected from the front (in the car) cover to that brass bolt.  My arrangement has not had any electrical problems that I am aware of.

 

I also have a stainless wire braid covered fuel line from the firewall bulkhead fitting to the fuel rail on the engine.  I have seen no damage to it.  The fact that your wire braid on the fuel line has been burnt suggests that it might have intermittently served as the engine ground at one time or another.  The braid must not have conducted a large current for very long or it would been destroyed completely.  I can't think of a worse place to have an uncontrolled resistance heater than on that fuel line.  Verifying the integrity of the ground from the engine to the airframe and from the battery to the airframe certainly seems like a worthwhile endeavor.

 

Depending on the details of the alternator installation, an intermittent connection inside the battery also might be a possibility although this would not explain the damage to the fuel line braid.

 

FWIW

 

Steve Boese

RV6A, 1986 13B NA, RD1A, EC2