17.5 Propeller Ice Protection Flashcards
What does ice formation produce?
A distortion to the Aerofoil,
Vibrations,
Lower propeller efficiency.
What regions are most at risk from icing?
Propeller blades,
Spinner,
Engine air intake.
When are anti icing systems activated?
Before the formation of ice.
Where is fluid anti icing equipment found?
Only on piston engine aircraft.
What is used to prevent ice formation?
Iso-Propyl-Alcohol.
What is the anti ice fluid injected into?
A U shaped slinger ring on each propeller.
What are the disadvantages of the anti ice system?
Weight of fluid to be carried.
Amount of fluid must be monitored.
System must be operated before icing occurs.
It is not able to remove impacted ice once it has formed.
What forces the anti ice fluid from the u shaped slinger ring to the grooved anti ice rubber boots?
Centrifugal force.
How is electrical power for electric de icing provided?
By spring loaded carbon brushes rubbing against copper slip rings attached to the back of the rotating hub.
How many electrical leads does a single element boot have?
2
How many electrical leads does a twin element boot have?
3
When is the de icing system used?
Only when the propellers are rotating for a short test periods.
What is employed to lessen the load on the aircraft electrical system?
Cyclic heating.
What does cyclic heating also do?
Prevent run-back.
What is the period which the heating elements remain energised between?
15 to 30s on time selection.
Complete cycle of 2 to 6 minutes.
What is used to accommodate both the propeller and spinner de icing requirements
A 2 speed cycling system.
When is a fast cycle used?
At higher air temperatures, when water concentrations are greater.
When is a slow cycle used?
In lower temperature ranges.
How long is a fast cycle?
Approx 2 mins.
What temperatures are the fast cycle used for?
+10 degrees to -6 degrees C
How long is the slow cycle?
Approx 6 mins.
For what temperatures is the slow cycle used for?
Below -6 degrees C.
