5 Reasons Why Humidity Impacts Engine Life

1. Water Vapor Leads to Corrosion

• Humid air contains water vapor, which enters the engine crankcase through combustion blow-by gases or passive ventilation systems.
• When the engine cools down after flight, the vapor condenses on internal components like:
• Camshafts
• Lifters
• Cylinders 
• Crankshaft journals
• These metal parts are often not coated in oil during engine inactivity, making them highly susceptible to surface rust and pitting corrosion.

2. No Positive Ventilation As Mentioned Previously.

• GA aircraft engines typically lack a PCV (Positive Crankcase Ventilation) system, so moisture isn't actively removed.
• Most rely on a passive breather tube, which works best only when the aircraft is flying.
• On the ground, humidity collects and stays in the crankcase, creating a corrosive environment.

3. Short Flights Worsen the Problem

• Frequent short hops may not fully evaporate internal moisture.
• This leaves residual condensation behind, accelerating corrosion if the aircraft is parked afterward.

4. Corrosion Causes Mechanical Wear

• As corrosion develops, it damages smooth metal surfaces—especially critical parts like:
• Lifters (which ride against the cam lobes)
• Camshafts (which control valve timing)
• Cylinders (steel cylinder liners employed in Continental engines)
• Corroded components can cause metal-on-metal wear, spalling, and pitting during startup.
• This leads to premature engine wear, loss of compression, and even catastrophic failure.

   

                     

5. Humidity Is Worse in Certain Environments

• Coastal areas have salt-laden humidity, which speeds up corrosion dramatically.
• Cold climates encourage condensation when engines are warmed and then stored in unheated hangars.