Icing Flashcards
What is drizzle
Diameter <0.5mm
What is fog
When vis <1000m
Rain is
Diameter >0.5mm
Difference between dry and wet snow
Dry = ambient temp below freezing
Wet = ambient temp above freezing
How does icing affect Stall speed AOA Lift Drag
Stalling speed increase up to 5%
Stalling AOA decreases by 3°
Reduction of lift by up to 30%
Increases drag by 40%
EPR over reads
What document relates to ground de icing and anti icing
Doc 9640
Manual or de / anti icing
Clean aircraft concept
Critical surfaces must be free of ice
Allowed up to:
3mm underside of wing of frost
3mm of frost on top of fuselage as long as paint markings can still be seen
Type 1 de icing fluid
Short hold over time
Rapid fluid failure
Older type = clear colour
New type = orange colour
Has no thickener in it
Type 2 de icing fluid
straw coloured
Has a thickener in it
Type 3 de icing fluid
Low rotational speed
Holdover time greater than 1 but less than 2
No assigned colour
Type 4 de icing fluid
Advanced thickening
High airspeed
Green colour
= longest holdover time
What are anti icing fluids based from
Glycol
One step de icing
Heated anti icing fluid
2 step de icing
First step = de icing
2nd step = anti icing
De/ anti icing fluid limitations
Lowest operational use temp (LOUT)
Repeated use of thickening agents cause residue to collect in aerodynamic quiet areas
= type 4 worst for it
