Class A-B-C Extinguishers Damage Aircraft
This information comes from the newsletter of the State of Arkansas Department of Aeronautics.
We are beginning to see an epidemic of Class A-B-C all-purpose fire extinguishers on airport ramps and airport service vehicles, including fuel trucks servicing our aircraft.
This poses a severe aircraft damage problem for all aircraft operators. The A-B-C extinguishers have excellent firefighting capability, but the monammonium-phosphate chemical agent melts and flows when it comes into contact with heat. This is how it gets its Class A rating. This chemical is highly corrosive to aluminum, and once it contacts hot aluminum and flows down into the structural cracks and crevices, it cannot be washed out in the same way the B-C dry chemical agents can be.
Once an A-B-C extinguisher is used on an airplane, it is necessary to disassemble the aircraft piece-by-piece and rivet-by-rivet to accomplish cleanup. Failure to do so will result in destruction of the aircraft by corrosion.
The purpose of first aid fire protection (fire extinguishers) is to get control of the fire early and minimize the damage. As you can see, the use of an A-B-C extinguisher on a small aircraft fire may extinguish the fire, but it still causes as much or more damage than the fire itself. We can save the aircraft from the fire, but lose it to the extinguishing agent.
This is a serious education problem that we as aircraft operators must face. We have had excellent cooperation from the contractors and airport fire departments that have been contacted concerning the problem-once the problem was explained to them. Please pass the word along to your airport operators and servicing contractors that A-B-C extinguishers should not be located where they might be used on an aircraft. Use B-C extinguishers instead.