They are usually composed of metal, plastic, or fiberglass and may be removed for inspection, replacement, or repair. The structural stability of the aircraft is not reliant on rigid detachable tanks. These tanks are typically seen in smaller general aviation planes like the Cessna 172. Bigger airplanes use integral fuel tanks which cannot be removed. The main advantage of removable tanks is that they can be replaced if they are damaged. This is important because small holes in tanks can lead to leaks that would otherwise be detectable during routine inspections. Replacement tanks can also have new colors applied to them without having to replace the whole tank! Disadvantages include extra weight and cost. Removable tanks can also take up more space when parked which can be problematic for smaller planes. Most large airplanes use integral tanks because they need the strength and durability that only a single piece of metal can give them. They are also less likely to leak because there are no openings for water to get into. Finally, some tanks are made from materials that can't be replaced. For example, a plane might use carbon fiber tanks which can only be replaced by replacing the whole tank! You should know that any material that can be used to make food containers can be used to make an airplane tank. Some common materials include aluminum, polycarbonate, and glass.