Types of Corrosion in Aircraft
Like most complex metal systems, aircraft are susceptible to corrosion. This type of damage affects not only the appearance of an aircraft but also its performance and reliability. As a result, it's important to be able to recognize different types of aircraft corrosion and take action to address them when necessary.
What Is Aircraft Corrosion?
Aircraft corrosion is rust that appears on the metal surfaces and components of an aircraft. It occurs when unprotected metal comes into contact with oxygen in the atmosphere. A number of factors accelerate aircraft corrosion, including exposure to acid and pollutants, poor preparation before painting and high levels of moisture. Depending on the metal affected, rust may look different. For example, it appears grayish-white on aluminum and reddish-brown on ferrous metals like steel.
Corrosion can also occur on the surface of an aircraft or in more hidden areas, so it's important to inspect the machine thoroughly. The issue commonly appears on metal components such as propellers, battery boxes, cylinder fins and piano-type control hinges as well as around fuel tanks.
What Are the Types of Aircraft Corrosion?
Aircraft corrosion can be broken down into several different categories depending on what causes the corrosion, where it's located and what it looks like. Distinct types of corrosion in aircraft to be aware of include:
- Surface corrosion: The most common type of aircraft corrosion, surface corrosion occurs when metal on the surface of an aircraft oxidizes, such as when paint wears away. Typically, you can recognize surface corrosion by the roughening, pitting or etching of surface metal and the presence of grey-white powdery deposits on aluminum. However, another type of surface corrosion called filiform corrosion may resemble small worms underneath the paint surface, eventually leading to bubbling and cracking.
- Dissimilar metal corrosion: Dissimilar metal corrosion appears when dissimilar metal parts come into contact with each other in the presence of a conductor. This type of electrochemical corrosion can cause extensive pitting damage. It often takes place out of sight, making it particularly dangerous.
- Intergranular corrosion: This type of corrosion affects the grain boundaries of an alloy, so it's often related to a lack of uniformity in alloy structure. Although intergranular corrosion often exists without surface evidence, it can lead to the lifting and flaking of surface metal over time. Extruded components may be particularly susceptible.
- Stress corrosion: As the name suggests, stress corrosion develops when parts such as landing gear and engine crankshafts are put under sustained tensile stress in corrosive environments, sometimes leading to cracking and failure.
- Fretting corrosion: Fretting corrosion is caused by the slight relative motion of two mating surfaces on an aircraft. Characterized by significant pitting and fine debris, this type of aircraft corrosion is greatly accelerated when water vapor is present.
Contact JETechnology Solutions to Learn More
Corrosion removal and treatment through abrasion may be possible for light surface corrosion. However, if the issue has caused significant damage to a component, replacement is the only safe option. Protect maintenance workers while they tackle the job by ensuring you have aircraft maintenance stands that provide proper fall protection.
At JETechnology, we have more than 75 years of experience manufacturing custom maintenance stands for military and commercial customers. To learn more, contact us online today.