PUREair Protection Against Heavy Rain

Rain is a product of the condensation of atmospheric water vapor that is deposited on the earth's surface. It forms when separate drops of water fall to the Earth's surface from clouds. Not all rain reaches the surface; some evaporates while falling through dry air.

Rain is classified according to the amount of precipitation: 

Classification Rate of Precipitation
Very light rain < 0.25 mm/hour
Light rain  Between 0.25 to 1.0 mm/hour
Moderate rain Between 1.0 to 4.0 mm/hour
Heavy rain Between 4.0 to 16.0 mm/hour
Very heavy rain Between 16.0 to 50.0 mm/hour
Extreme rain > 50.0 mm/hour


Heavy rain can be a serious problem for some helicopters and the resulting damage can be similar to Foreign Object Damage (FOD). In certain conditions, where water accumulates on the fuselage at a stagnation point upstream of the engine air inlets, a mere half cup-full ingested as a slug is enough to cause engine flame out.

The Solution

The PUREair system separates water from the main engine airflow. Any remaining water that does enter the engine inlet is in the form of a harmless spray, which has no significant detrimental effect whatsoever on engine operation.

Although a PUREair system will greatly alleviate the hazard created by heavy rain, the helicopter’s flight manual instructions must strictly be adhered to at all times.
The Ultimate in Helicopter Engine Protection
PUREair - The Ultimate in Helicopter Engine Protection
Why PUREair?
Why Choose PUREair?
PUREair systems offers the ultimate in helicopter engine protection
More than fifty different designs have been certified
How Does It Work?
How Does it Work?
Pall PUREair system training program
Design and Testing
Design and Testing
Pall's design and engineering expertise
PUREair Services
PUREair - Repairs and Support Services
Maintenance guidelines and global contact details