Your Aircraft is More Likely to Rust Out Than Wear Out
How To Prevent Corrosion in Your Aircraft’s Engine, Airframe, and Systems
Corrosion poses a significant threat not only to your engine but also to your airframe and various systems. While we briefly touched upon the issue (and its solution) of engine corrosion in another blog post, its importance warrants further discussion here. This section delves into both engine and airframe corrosion, but it’s essential to note that corrosion can affect other areas, such as avionics. For instance, contact corrosion of your equipment’s connectors can be mitigated by storing the aircraft in a dry, temperature-controlled hangar and by cleaning and applying contact spray if corrosion begins.
The Basic Process of Corrosion
The most prevalent types of corrosion arise from electrochemical reactions. Galvanic corrosion occurs when reduction and oxidation reactions take place between different metals in contact. This type of corrosion materialises when two dissimilar metals are in contact, and an electrolyte solution is nearby. This situation forms what’s known as a corrosion cell, which can be thought of as a short-circuited galvanic cell. Electrochemical corrosion can manifest wherever two unlike metals are in contact—this can even include foreign inclusions on a metal surface. In such reactions, the less noble metal (anode) invariably deteriorates. The rate of this electrochemical corrosion depends on the electrolyte’s conductivity. For galvanic corrosion to occur, the following elements are necessary:
- Dissimilar metals
- Anode
- Cathode
- Electrolyte solution
- (Condensed) Water mixed with:
- CO2/SO4 from the atmosphere,
- Salts,
- Acids, or
- Other impurities
- (Condensed) Water mixed with:
- Electrical contact
- Dissimilar metals
In the case of electrolytic corrosion, often found in electronic equipment, water or other moisture gets trapped between two electrical contacts with an electrical voltage between them, leading to the formation of an unintended electrolytic cell.
How to Protect Your Engine
There are several measures that an informed pilot-owner can take to prevent corrosion in the internal parts of your aircraft engine.
Fly Your Aircraft Regularly
It’s crucial to fly your aircraft consistently—at least once every week or two. Regular flying maintains the protective oil film on the parts and helps evaporate any accumulated water in the oil. Merely pulling the propeller by hand or performing a ground run is not enough—in fact, these actions can exacerbate the issue. Manually pulling the propeller can strip the oil from vital parts like lifter faces and cam lobes. Ground runs don’t heat the engine sufficiently to evaporate the water in the oil, and they may even introduce more water since it’s a byproduct of combustion. If the engine and oil aren’t adequately heated, water can build up in the oil, creating an environment conducive to acid formation and subsequent corrosion.
Park Your Aircraft in an Insulated, Temperature-Controlled Hangar
One significant advantage of using an insulated, temperature-controlled hangar is the protection it offers against both internal and external corrosion. A hangar not only shields your aircraft from the elements but also moderates daily temperature variations. This regulation prevents drastic temperature changes, which, combined with air and crankcase humidity, can cause condensation—another factor contributing to corrosion.
Use High-Quality Aviation Oil
Opt for high-quality single-grade engine oil primarily, resorting to multi-grade oil temporarily only when required due to temperature fluctuations (like in cold conditions). Change your oil and oil filter consistently—either every 50 flight hours or every four months, whichever comes first. Always avoid using synthetic or semi-synthetic oils for engines that operate on leaded fuel.
Use ASL CamGuard Aviation
We strongly recommend using ASL CamGuard Aviation oil additive, particularly for its remarkable anti-rust and anti-wear properties, especially when the engine is operated irregularly. Its efficiency is substantiated both through rigorous laboratory testing and real-world applications.
- Offers Modern Protection: It is a blend of high-performance additives that enhance piston aircraft oils, ensuring top-tier engine protection. Owing to FAA/EASA regulations and associated costs, even the latest commercial aircraft oil technology can seem outdated.
- Tackles Comprehensive Issues: It addresses the multifaceted, intertwined challenges of corrosion, deposits, and wear common in air-cooled piston aircraft engines.
- Combats Corrosion: Contains potent multi-metal corrosion inhibitors that stave off rust and corrosion, especially in engines used infrequently. Lack of regular engine use can lead to the formation of rust pits on cam and lifter surfaces. Such pitting can eventually lead to catastrophic spalling wear, necessitating an early engine overhaul.
- Reduces Wear: The product features advanced anti-wear additives that significantly minimise wear on components like cams, lifters, cylinders, rings, gears, and valve guides.
- Prevents Dry Start Wear: It ensures that an active lubricant film remains on critical components, even after extended periods of inactivity, thus preventing wear from “dry starts”.
- Maintains Cleanliness: ASL CamGuard Aviation employs unique ashless deposit control additives to prevent varnish and carbon deposit formation throughout the engine.
- Revives Older Engines: Using it in ageing engines can help in restoring component functionality, freeing up sticky rings and valves, improving compression rates, and decreasing oil consumption.
- Conditions Seals: It contains seal conditioners that counteract the effects of heat and ageing, ensuring seals remain pliant, flexible, and as good as new.
Preserve Your Aircraft Engine If Not Flown for 30 or More Days
While engine preservation is crucial when your aircraft isn’t flown for extended periods, many pilot-owners neglect this step. It’s puzzling why some choose to forgo this maintenance, perhaps due to uncertainty about the effort and cost involved. However, preserving your aircraft engine is neither complex nor pricey. In fact, informed pilot-owners can undertake this task themselves, as it falls under the scope of limited pilot-owner maintenance.
To simplify the preservation process, consider ordering a preservation kit from Tanis Aircraft Products. Carry out the preservation in line with the guidance found in the manufacturer’s service letters or Standard Practice Maintenance Manuals. The following documents are applicable for Continental or Lycoming engines, respectively.
Continental
- SIL99-1
- Continental Standard Practice Maintenance Manual M-0
Lycoming
- SL-L180B
The engine preservation kits cater to both four and six-cylinder engines. Each kit is comprehensive, save for the MIL-L-6082C (SAE J1966), Grade 1100, mineral aircraft engine oil. This needs to be procured separately: a four-cylinder engine requires mixing 6 quarts of this oil with the supplied “MIL-C-6529C Type 1” concentrated preservative compound, while a six-cylinder engine needs up to 12 quarts. The instructions for both installation and removal (when returning the engine to service) span less than a page.
How to Protect Your Airframe
There are several proactive steps an informed pilot-owner can take to prevent corrosion in the airframe.
Fly Your Aircraft Regularly
Much like the engine, the aircraft’s airframe and systems benefit from regular operation. Regular use prevents moving parts, such as brakes, trim systems, actuators, and even door hinges, from seizing due to corrosion. Consistent movement ensures that moisture doesn’t remain trapped for extended periods, whether it’s water in openings or bearings from a landing on a damp runway or simply due to condensation because of high atmospheric humidity. Additionally, some components might receive lubrication during standard operation.
Park Your Aircraft in an Insulated, Temperature-Controlled Hangar
We’ve previously touched upon the advantages of shielding your aircraft from the elements and the peril of temperature fluctuations that can cause condensation. However, there are additional considerations. Storing your aircraft in a hangar protects it from potential damage from chemicals used to combat ice on taxiways, runways, and nearby aircraft. These chemicals pose a risk, facilitating corrosion when they come into contact with your aircraft. Moreover, it’s crucial to underscore the importance of protecting your aircraft from natural elements. Beyond the obvious threats of rain, hail, and wind, your aircraft also faces the damaging effects of UV radiation, which degrades its paint over time.
Ensure Your Aircraft Paint Remains in Prime Condition
Maintaining a high-quality paint job is one of the most effective measures against external airframe corrosion. Regularly inspect and ensure that your aircraft paint is in optimal condition, and shield it from environmental factors when not in use. Utilising an aircraft hangar and employing aircraft covers during trips are excellent protective measures. Besides its protective qualities, a pristine paint job is visually appealing and simplifies cleaning.
Consider Applying Corrosion Protection
For many legacy aircraft, the interior of the airframe isn’t adequately shielded against corrosion and should be considered for protection. Two primary systems of corrosion preventive compounds are available, each with its unique benefits and drawbacks:
- Waxy Film Type:
- LPS 3 Premier Rust Inhibitor
- Boeshield T-9
- Advantages: These waxy film formers tend to last longer, providing protection for three to four years between applications. They also minimise “weeping” after application, which typically lasts only a few days.
- Thin Film Dielectric (TFD) / Fluid Thin Film Coating (FTFC):
- ACF-50
- CorrosionX®
- Advantages/Disadvantages: These thin film dielectrics excel in penetration, effectively neutralising active corrosion. However, they need reapplication more frequently, typically every two years, and may exhibit prolonged “weeping” that can last weeks or even months post-application.
- Waxy Film Type:
Conclusion
Safeguarding an aircraft from corrosion is a multifaceted approach that demands diligence, knowledge, and the right resources. As pilot-owners, recognising and implementing these protective measures can greatly extend the life of your aircraft, ensuring many more years of safe and enjoyable flights.
Regular Flight and Operation
The longevity and optimal performance of an aircraft don’t merely rest upon regular maintenance; it hinges significantly on the meticulous prevention of corrosion in both its engine and airframe. This blog post underscored the critical nature of regular flights, emphasising how consistent operation ensures not only the functionality of essential parts but also keeps moisture and other corrosive elements at bay.
The Shield of Sheltered Storage
Additionally, the importance of housing your aircraft in an insulated, temperature-controlled hangar cannot be overstated. Such a setting not only shields your plane from the unpredictable wrath of natural elements but also from potential corrosive chemicals that abound in airport environments. UV radiation, while often overlooked, poses a significant threat to an aircraft’s paint, further emphasising the need for sheltered storage.
Airframe Protection Techniques
On the airframe front, a pristine paint job serves as the first line of defence against external corrosion. But, for an even more robust protection, considering the application of corrosion preventive compounds becomes imperative. With options ranging from waxy film types to thin film dielectrics, each offers unique benefits tailored to various needs.
Engine Care and Maintenance
Moreover, it’s not just the external protection that counts. Internally, the quality of engine oil used, coupled with potent additives like ASL CamGuard Aviation, plays a pivotal role in maintaining the engine’s health. When the aircraft isn’t in use, especially for extended periods, proactive measures such as engine preservation ensure that it remains in top condition.
About Quest Aeronautics
Quest Aeronautics is a state-certified engineering office for aviation, dedicated to shaping the future of general aviation by providing innovative and cost-effective solutions to enhance aircraft performance and operations. With a focus on CS/FAR-23 and experimental/amateur-built (E/A-B) aircraft, Quest Aeronautics provides a range of services including flight testing, aircraft operations and maintenance consulting, high-quality aviation products, and tailored support for E/A-B projects. Collaborating with industry-leading partners, Quest Aeronautics is committed to delivering unparalleled support and expertise to individuals and organisations in the general aviation market.
About Author
Sebastian, the founder of Quest Aeronautics, is a driven and enthusiastic individual with a passion for aviation. Before delving into aviation, he gained valuable experience as a chemical process engineer and laboratory technician. Sebastian holds a Master of Science in Engineering and a commercial pilot licence, with several fixed-wing aircraft ratings under his belt. He has also completed an introduction course for fixed-wing performance and flying qualities flight testing at the National Test Pilot School in Mojave, CA and is compliance verification engineer for flight.