Spotting, Treating, and Preventing Corrosion

Corrosion prevention has far-reaching effects on the fleet.


To his credit, Scott Nelson decided to purchase a flexible borescope, so that he could look into the 182’s tightest areas. A flexible borescope consists of an eyepiece that is connected by fiberoptic cable to a lens at the other end, which is usually fitted with lights. Like a plumbing snake, the borescope can be bent and guided around corners and angles, making it ideal for inspecting an aircraft’s many nooks and crannies. Since acquiring it, Nelson has found similar corrosion in many other aircraft that have come into his hangar.

There are other visual techniques for detecting corrosion, says Dr. Roberge. “Look carefully at the skin of the aircraft; can you detect bulging?” he tells AMT. “If you can, then chances are that corrosion has taken place within and needs to be attended to.” Other more sophisticated visual inspection methods include penetrant flaw detection, magnetic particles, eddy current flaw detection, ultrasonic flaw detection, mechanical impedance analysis, and X-rays.

Fighting corrosion

Once corrosion has been detected, treatment is a must. In some cases, the damage is superficial enough to be removed, and then for the repaired area to be protected with anti-corrosion products. In others, corroded components may have to be removed and replaced.

Traditionally, technicians have employed wax, oil, and paint in such areas; treatments that are both messy and have to be removed before future inspections can be done. In contrast, newer products such as NO COR are clean, transparent, and do not have to be removed for further inspections. Other anti-corrosion products of note include Corrosion Technologies’ CorrosionX Aviation spray penetrant, which can be sprayed over existing corrosion to displace moisture and prevent the further migration of electrons; and Granitize Aviation’s Xzilon 3AECI Aircraft Exterior Corrosion Inhibitor, which prevents oxidation on exterior paint and bright work.

Vigilance: the best defense

“Airframe corrosion doesn’t happen overnight,” says Peter Burgher. “It can take a year or more for corrosion to seriously weaken an airframe, which is why early detection is so important.”

This being the case, the best defense against corrosion is thorough and regular airframe inspection, using a range of available techniques and tools. The regularity of such inspections is typically governed by an aircraft’s regular maintenance schedule; however, those flying in corrosion-prone areas (such as seaside coastal regions) would be wise to look for corrosion more often.

One piece of advice: Go out and buy a flexible borescope, and conduct nose-to-tail inspections of all your customers’ aircraft. Yes, it will take time, and could even cost you money for those customers who hesitate to pay. However, the hidden corrosion your shop will likely find, and the resulting repairs that you will be paid to perform, will likely more than compensate for the time and effort spent. Most importantly, these efforts may well save some customers’ lives and aircraft, which is what professional aircraft maintenance is really all about.

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