Ice protection - INTRODUCTION

INTRODUCTION

Ice protection

1. Icing of the engine and the leading edges of the intake duct can occur during flight through clouds containing  supercooled  water  droplets  or  during ground operation in freezing fog. Protection against ice formation may be required since icing of these regions can considerably restrict the airflow through the engine, causing a loss in performance and possible  malfunction  of  the  engine.  Additionally, damage may result from ice breaking away and being ingested into the engine or hitting the acoustic material lining the intake duct.

Fig. 13-1 Areas typically considered for ice protection.

2. An ice protection system must effectively prevent ice formation within the operational requirements of the particular aircraft. The system must be reliable, easy  to  maintain,  present  no  excessive  weight penalty  and  cause  no  serious  loss  in  engine performance when in operation.

3. Analyses are carried out to determine whether ice protection is required and, if so, the heat input required to limit ice build up to acceptable levels. Fig. 13-1 illustrates the areas of a turbo-fan engine typically considered for ice protection.

Fig. 13-2 Hot air ice protection.

Fig. 13-3 Combination of hot air, oil and electrical ice protection.

4. There are two basic systems of ice protection; turbo-jet engines generally use a hot air supply (fig. 13-2), and turbo-propeller engines use electrical power or a combination of electrical power and hot air.  Protection  may  be  supplemented  by  the circulation of hot oil around the air intake as shown in fig. 13-3.  The hot air system is generally used to prevent the formation of ice and is known as an anti- icing system. The electrical power system is used to break up ice that has formed on surfaces and is known as a de-icing system.