Ice and Rain Protection

Question 1

What two types of ice detectors are used on CG Aircraft?

Answer 1

Visual and electric.

Question 2

What is a commonly used visual ice detector on fixed wing aircraft?

Answer 2

A black dot painted on the leading edge of a wing in a position visible from the cockpit. As ice accumulates, it will be visible on the dot.

Question 3

How do electronic ice detectors work and where are they normally positioned?

Answer 3

Use an electronic probe or rotating cylinder to sense ice accumulation and actuate an ice warning in the cockpit. Engine intake or forward fuselage.

Question 4

What are two common methods to prevent and/or eliminate ice formation on aircraft components?

Answer 4

Thermal electric and thermal pneumatic.

Question 5

Describe the electric anti ice method.

Answer 5

The heating element is an electrical resistance wire that is embedded into the component.

Question 6

With are some examples of components that use electric anti ice?

Answer 6

Windscreens, pitot/static ports, propeller boots/propeller spinners, stall warning devices, main and tail rotor leading edges/main rotor droop stops (MH-60), Engine Inlets (HC-144)

Question 7

Describe the pnuematic anti ice method.

Answer 7

Utilizes bleed air that is directed through the anti-icing valve into a common manifold, then manifold hot air is mixed with ambient air and directed into ducts, supplying air to the leading edge of wings and empennages.

Question 8

In addition to the wing and empennage, bleed air is directed to what components for anti ice?

Answer 8

Wing/empennage inflatable boots (HC-130J, HC-144) and Engine inlets (HC-130)

Question 9

What is the typical temperature range for aircraft windscreens?

Answer 9

70-115* F (21.1-46.1*C)

Question 10

What are the two types of electrical heating elements used in the construction of windscreen anti-ice systems?

Answer 10

Oxide coating and resistive wiring.

Question 11

Describe oxide coating in windscreens.

Answer 11

Coating is a layer of stannic oxide. Stannic is an alloy of silver and lead. Stannic oxide has a high resistance to electrical current; therefore, when current is applied, it flows through the oxide and the power is dissipated in the form of heat.

Question 12

Describe resistive wire in windscreens.

Answer 12

Uses a heating element made of a wire which has a high resistance to electrical energy. The wire dissipates the energy in the form of heat.

Question 13

What are the two methods of deicing?

Answer 13

Resistive wire electrical heating element and externally mounted flexible boots.

Question 14

Describe electrical heat element deicing.

Answer 14

The element is only energized long enough to break the bond between he ice and the aircraft’s surface.

Question 15

Describe flexible boot deicing.

Answer 15

Allows for the formation of ice on the leading edge of the primary flight surfaces and removes it by inflating and expanding the leading edge surface.

Question 16

Name some components commonly deiced by the use of a resistive wire heating element:

Answer 16

Main rotor blades, tail rotor blades, propellers, propeller spinners.

Question 17

Name the primary flight control surfaces that are deiced by the use of inflating boots:

Answer 17

Wing boots, tail boots (vertical and horizontal stabilizer) Empennage root

Question 18

What area is most susceptible to icing on a rotating aircraft component?

Answer 18

The leading edge and the area toward the center of the turning component.

Question 19

Why would you prefer deicing over anti-icing on on rotating aircraft components?

Answer 19

If the leading edge were anti-iced continuously to prevent ice formation, the water would flow toward the blade tip and trailing edge. As the water passed to the unheated portion of the blade, it would turn to ice on the trailing edge and cause vibrations and disrupt airflow. (It would also require larger heating elements and a significant load on the aircraft’s electrical system.)

Question 20

What are the two methods used to mount electrical heating elements and why?

Answer 20

Externally and internally. The purpose for externally mounted heating elements is for removal if the element becomes inoperative. Internally mounted heating elements are an integrated part of the component, and if it fails, the component is non-repairable.

Question 21

What components are deiced using externally mounted electrical heating elements?

Answer 21

Main Rotor Blades, Tail Rotor Blades, and Propeller Blades

Question 22

What is one aircraft component that uses an internal de-ice and anti-ice element?

Answer 22

Propeller Spinner