Incident Overview
During a flight tasked with dispensing aerial incendiary devices (AIDs) for controlled forest burning, a fire erupted in an extra supply of AID balls located in the canopy bubble forward of the seats. The AIDs were 1.25-inch diameter polystyrene balls containing potassium permanganate, which were injected with ethylene glycol prior to being dropped from the aircraft by a dispensing machine. The machine was installed on the cabin floor in front of the right door opening.
Aerial Incendiary Devices
The AID balls were originally shipped in black plastic bags packed inside corrugated paper cartons. The extra supply carried on the aircraft had been removed from the cartons and were stored directly in the plastic bags. Operating instructions allowed for extra cartons of AIDs to be carried in the cabin of the aircraft if they were securely fastened.
Fire and Emergency Response
After the fire erupted, the pilot attempted to land on a nearby road but lost control of the aircraft because of the fire. The crewmember did not jettison the AID dispenser, as the fire was located in the canopy bubble rather than near the dispenser unit.
Storage and Operating Procedures
The extra AID balls involved in the fire were stored in plastic bags inside the canopy bubble. The original shipping containers (corrugated paper cartons) were not used for the extra supply carried in the aircraft. The source document does not specify whether the extra supply was securely fastened as per operating instructions.