Humidity & Corrosion
Example: Corrosion rate of iron versus relative humidity.
(Corrosion and Corrosion Control, by R. Winston Revie and Herbert H. Uhlig 2008)
When does corrosion Develop?
The green zone, 0-40% relative humidity, won't allow corrosion to develop when the aircraft isn’t flown for more than two weeks.
40-60% there is some corrosion that begins to develop on the engine if it is left stationary for more than two weeks.
At 60% or more relative humidity, the corrosion growth skyrockets exponentially.
Is my engine at risk for corrosion?
The map below shows the relative humidity across the nation. If the relative humidity is above 40% then corrosion can develop when not flying for more than two weeks. Also, keep in mind these are annual averages. Some places might require a DryBot for only part of the year, where in other places year-round engine dehydration is critical.
How does the drybot actually work?
The DryBot pumps air through a desiccant which provides a dry flow of air which is pumped into the engine. An onboard computer uses 12 sensors to continually monitor system performance. When the computer senses that the desiccant needs to be regenerated (heated to expel accumulated moisture), the DryBot automatically heats the desiccant and diverts the moist air flow through a port on the bottom of the DryBot. Once regenerated, the system cools and dry air is again provided to the aircraft engine.
How does dry air get delivered to the engine?
Most often, dry air is injected into the engine via the oil fill, dipstick, vent tube, or exhaust. The oil fill is preferred since it is easily accessible and provides dry air to the bottom end (crankshaft, cam, lifters) of the engine which is much more expensive to repair than the top (cylinders, pistons). The crankcase vent tube is viable albeit less desirable because it typically has freeze vents (slots or holes) which can introduce moist air to the air stream. The exhaust pipe is often most convenient on a 2 stroke engine. No matter which option is used, an air-tight seal between the dry air delivery tubing and input port is required so dry air is forced throughout the engine. Learn More >
How do i know the drybot is operating correctly?
The DryBot is continually using 12 sensors to monitor humidity, temperatures, currents, voltages, etc. and will flash an error code if any issues are detected. Otherwise, if the green light is on, you know the DryBot is generating dry air with positive air flow.
DryBot is a trademark of RPX Technologies, Inc.