Icing

	Icing tests evaluate the effect of accumulated ice on the operational capability of equipment. Two types of ice are commonly encountered: rime ice which is opaque and granular or glaze ice which is clear and smooth. Glaze ice is generally used for icing tests. Depending upon the operational environment of the product, icing can be caused by different mechanisms.
	Environment Cause Ground Equipment Freezing Rain or Drizzle Shipboard Equipment Sea Splash or Spray Airborne Equipment Rapid Changes in Temperature, Altitude and Humidity
	This test does not simulate snow conditions, snow loads or ice buildup on aircraft flying through supercooled clouds.

Ice Thickness

6mm - general conditions, light loading

13mm - general conditions, medium loading

37mm - heavy ground loading and marine mast loading

75mm - extremely heavy ground loading and marine deck loading.

Operational Considerations

Some equipment, covered with ice, may be expected to operate immediately without undergoing de-icing procedures, other equipment would not be expected to operate until some form of de-icing has taken place. Ice removal, if required, may be performed manually, or automatically by built-in ice-removal systems or a combination of both.

Effects

Bonds moving parts together.

Added weight to radar antennas, aerodynamic control surfaces, helicopter rotors, etc.

Increased footing hazards for personnel.

Interference with clearances between moving parts.

Induced structural failures.

Reduced airflow efficiency as in cooling systems or filters.

Impeded visibility through windshields and optical devices.

Degraded transmission of electromagnetic radiation.

Damage from mechanical, manual, or chemical ice removal measures.

Reduced efficiency of aerodynamic lifting and control surfaces.

Reduced (aircraft) stall margins.

Test Variables

Accumulated ice thickness

Ice removal method

Test temperatures and droplet sizes

Surfaces to which ice is to be applied

Wind Velocity

Operability and pass/fail criteria

Test Apparatus

Chamber with auxiliary instrumentation capable of maintaining and recording the test conditions.

Provisions to monitor the test specimen temperature.

Water spray delivery and drain system.

Provisions to measure Ice thickness.

Typical Test Procedure

1. Stabilize the test item temperature at 0° C (-0/+2°C).

2. Deliver a uniform, precooled water spray for 1 hour to allow water penetration into the test item crevices/openings.

3. Adjust the chamber air temperature to -10°C and maintain the water spray rate until the required thickness of ice has accumulated on the required surfaces.

4. Maintain the chamber air temperature for a minimum of 4 hours to allow the ice to harden.

5. Examine for physical damage, safety hazards and attempt to operate the test item.

6. If there is a failure or if the specification allows ice removal, remove the ice. Note the effectiveness of ice removal techniques used.

7. Stabilize the test item at standard ambient conditions and perform a post-test operational check.

8. Examine for physical damage, safety hazards and attempt to operate the test item.

9. Document (with photographs if necessary) the results.

Home | Test & Engineering Disciplines | Industries Served | Request a Quote | Travel Assistance

Copyright © 1999 American Environments Company Inc.