Becoming an Aerial Firefighting Craft
When turning a "regular" airplane or helicopter into a firefighting aircraft you must make a few attachments, but you needn't drastically change the structure of the aircraft. Many helicopters and airplanes can be retrofitted to handle a variety of firefighting equipment, including tanks, buckets, and water slings. These are not complex attachments and most mechanics can accomplish it without too much of a problem as long as they have the right equipment.
Tanks
You will need some sort of water dumping mechanism in order for your helicopter or fixed wing vehicle to become a firefighting aircraft. A tank is one of the most popular water containment objects out there, especially for precision water release. Most of the time, tanks are previously affixed to the vehicle, but you can also get a tank that can be retrofitted to your helicopter or fixed wing vehicle. This is one of the hardest types to retrofit to your plane or helicopter because it requires your vehicle to be restructured the most, unless you have a special type of helicopter.
Buckets
Buckets are one of the easiest things to equip a helicopter with, because it is basically just a pail on the end of a string. It is not as precise in water release as most of the other types, but it is still very reliable at firefighting. If you are in a financial pinch, then you can get a bucket much cheaper than most of the other firefighting equipment but it will not be as effective at firefighting.
Water Sling
A water sling is another common way to drop water on a forest or from an aircraft. It is easily attached to them as well, but it is just as unprecise as the bucket. The advantage of a sling over a bucket is that it is easier to dump the entire load. You only have to lower one of the ropes. It is also fairly inexpensive comparatively. They are also easily detachable, which makes for less headache and for more versatility in the firefighting field. A helicopter with a water sling can be quickly turned into a rescue helicopter, picking up people from out of the blaze. This is important if there is only one helicopter in the area, but if there are multiple helicopters, one could easily be used solely as a rescuer and the others could be used to carry water and focus on putting out the fire.