A Class BC fire extinguisher has no place in the cockpit of an aircraft. If activated, the powder residue will cause so much corrosion that the aircraft will be unairworthy.
Halon or CO2 are the only types of fire extinguishers that should be used around or on aircraft.
Even when using any dry powder extinguisher for a ground vehicle cabin fire you better be standing outside directing the discharge through an open door. The particulate is very fine, abrasive, caustic and carries a slight charge making it stick to every surface. Very un-good for eyes lungs etc, let alone the almost instant “hard IFR” effect in an enclosed cabin.