14 CFR § 29.851

Hand fire extinguishers. For hand fire extinguishers the following apply:

Each hand fire extinguisher must be approved.

The kinds and quantities of each extinguishing agent used must be appropriate to the kinds of fires likely to occur where that agent is used.

Each extinguisher for use in a personnel compartment must be designed to minimize the hazard of toxic gas concentrations.

Built-in fire extinguishers. If a built-in fire extinguishing system is required—

The capacity of each system, in relation to the volume of the compartment where used and the ventilation rate, must be adequate for any fire likely to occur in that compartment.

Each system must be installed so that—

No extinguishing agent likely to enter personnel compartments will be present in a quantity that is hazardous to the occupants; and

No discharge of the extinguisher can cause structural damage.