Black Wire Disease???

Common and inexpensive insulation for wire is poly vinyl chloride, PVC. Depending on the quality of the PVC used it is possible that it degrades over time to release chlorine gas or a chlorine compound. That would attack the copper wire as well as any tin plating on the wire.

I also believe the same phenomena gives rise to the degradation of TD 010 tanks at the feed point. Attacked as the PVC fuel tube degrades over time releasing chlorine gas which will attack the Delrin (acetal homopolymer) that the tank is moulded from. Seems to happen to NIB engines, not used ones, so maybe residual castor oil impedes or negates the reaction. I remove the fuel tube on 010 and 020 engines when not in use including new ones for this reason.

aeroland is correct.
It was that really cheap PVC type of insulation that caused the "black wire" syndrome.
It never happened on silicon insulated wire or any other wire that was not using the PVC (stiff) insulation.

Wonder what would have happened if they used the aluminum wire with the PVC insulation?
Probably the cheapest wire you could buy then?

sosam117 wrote:Wonder what would have happened if they used the aluminum wire with the PVC insulation? Probably the cheapest wire you could buy then?

Aluminum wiring was used in houses some time back, but was discontinued when they found that corrosion at connections was a contributing cause for house fires.

For electronics, aluminum wire doesn't solder well, probably why it was never used.

Its a verry common issue with older electronics.
Many of my older (but still working) reciever battery packs are on there second or even third cable.
Even the wire on the side of the switch is affected if kept connected.
Since the polarety of the battery has influence even without a current (or so small we can't measure) its more likely some form of galvanic corrosion.

If the chemistry of the insulation was the defining factor then the polarety should not make a diference and it should then also happen with wires not connected to a voltage source.
I also has this issue with nicad flight packs that use thicker silecone insulated high strand count copper wire.
So far it has not happed with lipo packs but thats likely becouse of the relative short lifspan of those packs.

Simplest way of dealing with this issue is to assume battery leads are a limited lifetime item.

GallopingGhostler wrote:For electronics, aluminum wire doesn't solder well, probably why it was never used.

Not sure how accurate but was told airliners use aluminium wires.
No soldering; all crimped connctions.

Also (at least in europe) the high voltage powerlines of the grid use aluminium around a steel core as conductor between the pylons..
For the same weight aluminium is a better conductor then copper.

cmulder wrote:Its a very common issue with older electronics.
..................

If the chemistry of the insulation was the defining factor then the polarety should not make a diference and it should then also happen with wires not connected to a voltage source.
..................
Simplest way of dealing with this issue is to assume battery leads are a limited lifetime item.

I've had the same issue with older NiCad packs. I usually changed out the leads at the end of the flying season by stripping the wiring back until it was again bright.  However, I was never comfortable with the replacement since I did not know if it migrated down both ends of the wire.

Since it seemed to be associated primarily with the negative wire, I suspect it was due to electrolysis induced corrosion.

cmulder wrote:Not sure how accurate but was told airliners use aluminium wires. No soldering; all crimped connctions. Also (at least in europe) the high voltage powerlines of the grid use aluminium around a steel core as conductor between the pylons.. For the same weight aluminium is a better conductor then copper.

Yup, all of you have valid points, things I never thought of before, but sound plausible.