Nothing creates more panic in the minds of mechanics, manufacturers, operators, and owners of an aircraft than these two words, “aircraft corrosion.” For an airplane mechanic, corrosion means lengthy and careful inspections in dark, damp, and hard-to-reach areas, generally followed by comprehensive and significant repairs.
For aircraft owners and operators, corrosion means that their plane will remain out of service for increasingly costly repairs, or in some cases, even an unfortunate and sizeable loss of asset value. When it comes to regulatory agencies, corrosion can be deemed as a life-threatening situation that must be addressed and prevented.
Factors Influencing Corrosion
Numerous factors affect the kind, cause, speed, and seriousness of metal corrosion. Some of these contributing factors can be controlled, while others cannot be controlled. The following are two significant factors that badly influence the corrosion process:
The environmental settings under which a plane is operated and maintained significantly affect its corrosion attributes. A marine atmosphere with increased moisture-laden air is considerably more harmful to an airplane as compared to a dry environment. Temperature factors are also vital as the intensity of electrochemical attack on aircraft body gets increased in a hot, moist climate.
Some of the controllable factors that affect the origin and expanse of corrosive attack on an aircraft include foreign substances that adhere to the metallic surfaces. Such foreign materials consist of:
- Atmospheric dust and soil particles
- Grease, oil, and engine exhaust residue
- Salt moisture and saltwater condensation
- Caustic cleaning solutions and spilled battery acids
- Welding flux residue
An airplane must be kept clean all the time to prevent the onset and spread of corrosion due to these foreign elements. The timing and degree of aircraft cleanliness and maintenance depend on different factors such as geographical location, type of operation, and aircraft model.
Many great efforts have been made in the recent past to improve the corrosion resistance capacity of aircraft. Enhancements in materials, insulations, surface treatments, and especially modern protective finishes all significantly add to the corrosion resistance ability of airplanes. The primary reason for making all these improvements is to decrease the overall maintenance effort and to improve reliability.
However, despite all these efforts, aircraft corrosion and its control is a highly pressing issue that needs continuous preventive maintenance. It’s recommended to consult the Material Safety Data Sheet MSDS during any corrosion control maintenance to get information on any chemicals utilized in the process.
Corrosion preventive maintenance usually contains the following particular functions:
- Sufficient cleaning
- Detailed periodic lubrication
- Comprehensive inspection for corrosion and malfunction of protective mechanisms
- Timely corrosion treatment and touch up of faded paint areas
- Removing all obstructions from drain holes
- Day-to-day draining of fuel cell sumps
- Day-to-day wipedown of uncovered sensitive areas
- Adequate ventilation on warm, sunny days and securing airplane against water during extreme weather
- Maximum usage of protective coverings on parked aircraft
It’s also recommended never to interrupt regular corrosion preventive maintenance, otherwise, the amount of maintenance needed to undo the corrosion damage will usually be quite high.
Corrosion-related inspection is a continuous process that should be performed regularly. However, overstressing a single corrosion issue after its discovery and forgetting about corrosion control until the next crisis happens is a dangerous, expensive, and troublesome practice. The majority of the scheduled maintenance checklists are detailed enough to cover all critical parts of an aircraft for their inspections. It’s best to utilize these checklists as a general guideline for corrosion-related aircraft inspections.