11.12 Ice And Rain Protection Flashcards
What 2 systems are there for rain protection?
- Windshield Wiper
- Rain repellent system
what negative effects does ice have on an aircraft? [3]
- increase in drag
- decrease in lift
- weight increase
what range of temperature can water droplets form clear ice on the surface of the aircraft?
0 degrees to -10 degrees
what ice is formed when the temperature drops below -10 degrees?
Rime-ice
whats is a thermal wing anti ice system?
where on the leading egde, heat is used to melt any ice formed
what 2 negative effects can ice have on engine inlets?
- disturbs air flow = a reduction in engine performance and compressor stall
- damage to fan blades and inlet vanes
what do engine inlets have to prevent ice build up?
thermal anti ice system
what is aerofoil de-icing?
using rubber boots on leading edges of wings and stabilisers rather than warm air from pnuematics
how do the rubber boots work? (aerofoil de-icing)
They inflate for a short time by pressurised air, cracking the ice which is blown away by the airflow
what type of ice detection is a probe on the front of the aircraft that collects ice where its visible to the pilots?
Optical Ice detector
what types of ice detection systems are there? [3]
- Optical ice detector
- rotary ice detector
- electronic ice detector
how do electronic ice detectors work?
Tips of the detector vibrate with a frequency that reduces with ice formation
where are thermal anti-ice systems are installed on the aircraft? [2]
- the wing
- engine
what is the name of the vales that connect the wing anti ice ducts to the pnuematics?
wing anti ice valve
where does the warm air come from to anti ice the engine?
directly from the engine
what valve connects the engine to the pneumatics to provide anti ice?
engine anti ice valve
what is found in the wing or engine anti ice ducts to spray them with hot air?
small holes
what duct is equipped to the leading edge when slats are installed for anti ice?
telescopic duct
what main valves is used to regulate the air coming from the pnuematics to the anti systems?
bleed valve
how many switches do the wing anti ice systems have? and why?
- 1
- they must always operate symmetrically as one may have a reduction in lift if not switched on.
how many switches are there for the engine anti ice system?
1 for each engine
when are anti ice systems normally operative?
during flight
when can you switch on the anti ice systems on the ground?
to check operation of the valves before flight
when are engine anti ice systems always available?
when there is bleed air from the engine
what types of valves can be found in the anti-ice system? [2]
- electrical motor operated valves
- solenoid controlled pressure operated valves
when would the solenoid controlled valve close by a spring?
when there is no pressure
how does a solenoid controlled valve operate? [2]
- de-energised solenoid = pressure from airflow fills the lower chamber of the valve cylinder, pushing the piston up, moving air in the top part of the cylinder to ambient. opens valve
- energised solenoid = brings high pressure to the upper part of the cylinder to equalise the pressure on both sides, but closes under spring pressure
what does the engine anti ice solenoid controlled valve do under a fail safe operation?
automatically open with no electrical power
what monitors valve position?
limit switches
when will a fault light illumincate on wing anti ice pushbutton?
when the pressure doesnt reach 14 psi
when does the aircraft only use 50% of AC power?
when on the ground
