How To Spot And Prevent Aircraft Corrosion

By Jason Zilberbrand, ASA, CAA, ISA AM, AOA AM, MRAeS

Let’s talk about one of the most significant aspects that can depreciate an aircraft immensely. We call it aircraft corrosion, and it can stop a potential buyer from ever closing a deal.

Any corrosion on a plane is severe and can cause an aircraft to fail during flight. Various levels of decay have caused fatal and non-fatal crashes, including an England Airbus A330 in 2013, a Georgia ASA Embraer in 1995, and a Netherlands Boeing 747 in 1992 that claimed 43 lives. We see more corrosion now than ever before, and impacted airframes run the gamut from single-engine piston through commercial aircraft.

The thing about aircraft corrosion is when an aircraft owner is told they have it, they sometimes find it hard to believe. But any pilot, mechanic, or aircraft owner with experience can tell when an aircraft is compromised because of corrosion.

How do you keep an eye out for aircraft corrosion, treat it, and prevent it from happening in the future? Keep on reading.

How To Spot Aircraft Corrosion

Aircraft corrosion can be well hidden and made unavailable to the naked eye. But in addition to sneaky spots of corrosion, there are a few major aspects to consider when purchasing an aircraft:

Avoid Buying A Patched Up Plane

One of the reasons you should always have a pre-purchase inspection is to look out for any patches or signs of corrosion repairs. Any signs of panel replacement or patching are signs of former damage to the aircraft, and while the damage may have been repaired properly, no one can guarantee the corrosion won’t reoccur. Unfortunately, many airframes that suffer from corrosion are either unrepairable or very costly to repair.

Now, this is where an aircraft’s logbook comes in handy. Any former damage, repairs, and other maintenance should be documented appropriately in its logbook. The logbooks, however, only shed light on things that were discovered, and more often than not, corrosion goes undetected until it’s too late. In fact, just this past week, I had a client walk away from an aircraft during pre-buy as heavy corrosion was discovered. The costs to repair would be substantial; worse yet, the aircraft never flew in known corrosive environments and was properly maintained.

Do Not Buy An Aircraft Based On Photos Alone

Photos hide a thousand blemishes and will not show an accurate overview of any corrosion. It is best practice never to buy an aircraft only by looking at some photos of it.

If you are using a good broker, they should conduct an in-person audit. Moreover, they should want to know more about an aircraft you are considering intimately.

Answering Your Questions About Aircraft Corrosion

Without continuing down the doom and gloom of corrosion, let’s answer the most common questions.

Are There Varying Types Of Aircraft Corrosion You Should Look Out For?

Yes, it’s important to note that different types of corrosion can appear on an aircraft. Much like any other object made out of metal, aircraft are susceptible to corrosion over time. The following are the most common forms of corrosion found on aircraft.

First, we have standard surface corrosion. This type of corrosion is typically due to the metal’s exposure to oxygen, meaning the paint that was once covering the metal has worn off.

Then, we have intergranular corrosion. This type of corrosion is severe and can be detrimental to an aircraft or any of its parts, causing cracking and delamination. If not appropriately heat-treated, high-strength aluminum alloys can be particularly affected by intergranular corrosion. This type of disintegration is challenging to control and stop. The most advanced form of this type of corrosion is called exfoliation corrosion.

Next, we have stress corrosion, often resulting from a reaction to the metal and a solvent like salt. Stress corrosion looks like a ton of cracking and scratches.

Then, there is crevice corrosion that looks like spotting or other material covering or near metal joints.

Finally, we have filiform corrosion caused by high slightly-acidic humidity. This type of corrosion appears in a worm-like pattern and begins in the coating system.

How Do You Treat Aircraft Corrosion The Right Way?

Here’s where following a refurbishing schedule will be beneficial. Understandably, an aircraft owner can potentially pour a lot of money into refurbishing an aircraft. But unlike other maintenance events, corrosion treatment starts with preventive maintenance. You would be surprised how many aircraft owners fail to wash and clean their aircraft on a regular basis. Even more surprising is how many owners wash a plane and do not dry it. Besides, a regular bath will allow you to recognize every single blemish and keep an eye on it. If you do note something, don’t ignore it, as it may already be too late.

How Can You Properly Prevent Corrosion?

While you may not control the atmosphere, you can avoid certain situations that may corrode your aircraft further. You can also apply protective coatings and use a stress relief heat treatment where possible. Corrosion inhibitors can also help reduce corrosion.

The most common reasons for an aircraft’s corrosion include:

Salt
Alkalis
Water
Acid
Atmospheric condition

Again, and most important, wash your aircraft regularly, and keep it clean and please dry it!

Finally, keep your aircraft stored in a dry and safe location. Improper storage can expose an aircraft to the elements, causing corrosion to occur even faster.

When shopping for a plane, take note of where it is based and how long it has been in its current location, obtain a background check of the aircraft and see if the plane ever had long term exposure to known corrosive environments, and if you are in doubt, call us VREF is here to help!

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