PUREair Protection Against Snow and Ice


Ice as a Challenge to Engine Protection

  Flight in icing conditions is a significant and a known hazard for all aircraft. The accretion of ice on an aircraft is caused by super-cooled water droplets impacting the aircraft’s surfaces and freezing.

Icing is among aviation's most serious weather hazards because it can severely reduce an aircraft’s performance during flight. Icing mostly occurs at lower altitudes, impacting small fixed wing aircraft and helicopters that fly slow and low. Icing causes mission delays during ground de-icing of aircraft, mission cancellations, and abortions because of forecast or actual in-flight icing.


Icing can take place on any exposed part of the aircraft and can generate several different types of hazards. For rotorcraft, these hazards can include: degradation of the aerodynamic performance of rotors, fouling of sensors and external moving parts, increased mass due to accreted ice, increased vibration (due to increased mass, shedding or changes in the aerodynamic profile of the rotor blades), reduced visibility through the windscreen and other windows, damage caused by shed ice, changes or reduction in air intake flow, ingestion of shed ice or slush.

The regulations state that, if a flight is to be made into known or forecast moderate icing conditions, the aircraft must be equipped with adequate de-icing or anti-icing equipment. The restrictions are stated in the operator's manual for each aircraft (See latest FAA recommendations).

“When a plane flies through super-cooled water droplets, ice accretion occurs on the air intakes. The ice deposit can cause aerodynamic airfoil degradation, or engine flame outs due to ice ingestion coming from the air intakes” (ONERA, French Aerospace Laboratory).


Snow Regulations for Helicopter Engines

“It must be shown that each turbine engine and its air inlet system can operate throughout the flight power range of the engine (including idling), in snow, both falling and blowing, without adverse effect on engine operation, within the limitations established for the rotorcraft” (ref JAR/FAR-27/29.1093). See latest FAA recommendations

Snow as a Challenge to Engine Protection

Helicopters tend to operate closer to the ground for longer periods of time than fixed wing aircraft. Therefore helicopter engines can be more exposed to ground environmental conditions, such as snow, ice and heavy rain. For example, landing on an unprepared field may result in snow being sucked into the engine air intake. In addition, wet snow can accumulate in the fuselage in front of the engine air inlet and then be ingested into the engine as concentrated slush.

Consequences of Snow in Engine Air Inlets

Blockage of the engine air inlet will limit the airflow through the engine. If there is a severe restriction, engine stall and flameout can occur.

If sufficient snow is ingested into the combustor system, compressor damage and engine flameout can be the result.

Therefore build-up of snow/ ice on the engine or the engine air intake must be avoided.

The PUREair Solution for Engine Protection against Snow and Ice

The PUREair system offers excellent protection against snow and icing. The system has been certified to JAR/FAR specifications on many applications, including re-circulating and falling snow, with no further flight restrictions on the helicopter.

Ice accretes on the front of the PUREair tube in a certain shape, due to the dynamics of the airflow entering the tubes. This allows flow to continue to the engine during this process. Once the ice has built up to a certain level, it sheds under its own weight or due to aerodynamic load.

PUREair systems are certified for operation in known and inadvertent snow and icing weather operation on many helicopters worldwide. The systems have proven service experience in the most severe environments with no degradation of engine performance.
The Ultimate in Helicopter Engine Protection
PUREair - The Ultimate in Helicopter Engine Protection
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