Hi DType
I had thought of that, looked at the applicable rule, and see some room for something like what you say.
(a) In each area where flammable fluids or vapors might escape by leakage of a fluid system, there must be means to minimize the probability of ignition of the fluids and vapors, and the resultant hazards if ignition does occur.
Leakage of electrolyte is associated with expansion and heating of the battery case, causing a crack.
Leakage, in the rule, is not constrained, but addressed only in that it may ignite.
If the temperature of the interior of the battery and its enclosure can be kept below the fluid's ignition (flash) point, leakage, per se, is not prohibited.
That satisfies "minimize the probability of ignition." It does not say "Possibility", and minimizing a "probability" is less constraining (easier) to do. So in the case of the fluid and vapor leakage, "possible" leakage is allowed.
Now, "the resultant hazards if ignition does occur." That means the results of ignition must be "minimized". That does not mean "controlled", or even "mitigated". If the burning electrolyte is contained in the enclosure, that would satisfy the "minimize" part of the langauge.
BUT:
Electrolyte escaped from the Battery in the JAL accident, and it is assumed it continued to burn as it flowed along the EE Bay decking. This would likely NOT be allowed by the rule, so "containment" enters the controlling language.
(2) Flammability characteristics of fluids, including effects of any combustible or absorbing materials.
What if the electrolyte, alight, puddled in an area of CFRP? (Carbon Fiber Reinforced Plastic). This is potentially a show stopper.
CFRP ignites at 580 degrees Fahrenheit. By demonstration, CFRP must be proven not to ignite at the temperature of burning electrolyte. If it cannot, the CFRP is combustible,
by rule, and leakage is prohibited. NEVER ALLOWED.
The fuselage is constructed of this material (CFRP). If it catches fire, it will burn on its own, in continuous fashion, until extinguished by an approved method. If it ignites in the Hold, extinguishment is not possible until landing. On board extinguishing is not provided, and would be in conflict with the rule making anyway, CFRP cannot ever be allowed to ignite, under any condition. What are the products of burning CFRP? If these combustion by-products entered the flight deck or cabin, is the air breathable?
Back to the drawing board. A box that cannot leak is required, by regulation. Any breach of the contents of the enclosure MUST be dumped overboard, if the contents are burning, the exterior of the Hull is at risk to ignite.