Corrosion from Salt Water
Seaplanes are often exposed to salt water, which can corrode the aircraft's metal. To lessen aircraft corrosion, seal metal against exposure. Although it is impossible to eliminate every electrolyte that can cause aircraft damage, there are many types of oils, greases, thin film dielectrics and waxes that can mitigate its effect.
Water on Propellers
Water can be very damaging to propellers, causing blades to split along their lengths. This is easy to detect because the leading edge will look like its fraying, normally at the tips of the blades. To fix blades that have water damage, maintenance technicians need to completely dress the leading edge to remove the spray cut and reprofile the blade tip.
Examining a seaplane before a flight is much more complicated than a landplane. Because the aircraft is on water, it is difficult to gain access to all parts of the airframe. Pilots have to reposition the aircraft while afloat to gain access to all the parts necessary to check.
The water pressure and physical stress of takeoff and landings on seaplanes can momentarily open tiny gaps between float components. Water can seep through these gaps and also enter in a small amount when the aircraft is sitting idly in the water. The accumulated water must be pumped out using a bilge pump for each compartment. Although it is normal to pump out water from each compartment, more than a quart of water from each may indicate a maintenance problem and this should be checked by a qualified aircraft mechanic.
Water forces on the aircraft float can lead to cumulative damage. This can be seen from distortion of the skin, dents or loose rivets. If the floats are made of fiberglass or composite material, the stress can be seen from cracked surfaces abrasions or signs of delamination.
When temperatures drop below freezing, ice can cause damage to float compartments and water rudders. A large amount of water expanding when it freezes inside the float can cause the seams to burst. Many seaplane owners store the floats upside down in the winter to allow thorough drainage.