Anti Icing Flashcards
De Icing
Removing Ice
Before flight or in flight
Anti Icing
Preventing ice from forming on and building on critical areas of airframe and engine
De icing and anti icing systems examples
Hot bleed air
Hot engine oil
Electrically heated mats
Pneumatically operated mat
Fluid de icing
Pneumatic system is a (anti ice)
De icing system
Thermal Anti Icing
Bleed air via duct work along leading edge/nacelle/windows and tail
Hot Rod
Detects icing - probe near cockpit window that is a visual indicator of icing conditions
Vibrating Rod
Probe mounted outside of fueslage Ona. Vibrator housing which vibrates the probe
Ice builds up frequency falls and ice warning given
40khz
Ice detection system
6 seconds heater switch - icing cycles restarts
Pressure Sensor
Hollow tube attached to aircraft
Pressure builds up in probe via hole in LE/TE
In ice condition leading edge holes becomes blocked by ice and negative pressure is created in the hollow tube
Moden System - Ice Detector
Reference loop - fixed voltage applied
Detector loop - higher voltages applied
Difference between the voltage of the two loops triggers warning on flight deck
Fluid Based ice protection
Fluid pumped from reservoir into perforated strip
Spread back to melt ice
Sequence is controller by a timer
Thermal Ice Protection
Bleed air or electrically heated mats
Anti ice system
LE slats/LE wing
Disadvantage of thermal ice protection
Performance penalty may have to be switched of during take off and in critical phases of flight
Jet Engine Anti Icing
Internal and use hot engine oil and internal engine air to heat fan and nose cone area of engine
No control over internal de icing system
How is engine nacelle heated by bleed air
Piccolo tube
Turboprop ice protection
Usually electrically heated mats
Heating elements of resistance wire or sprayed metal to air intake structure
Mats switched on and off in sequence to reduce loads
Ice deflector doors
Allow ice to be directed out to atmosphere than rather being drawn into engine
Where is ice more likely on turboprop
At the blade
Turboprops with odd number of blades are
Heated continuously
Pneumatic Boot System
A de icing system
Certain amount of ice is allowed to form then boot is inflated
Boots are then deflated
Used on piston engine
Only inflate for a few seconds
Ice requirements for a pneumatic boot system
Ice thickness of between 0.5cm and 1.5cm
Components on aircraft that require ice protection
Wing leading edge
Windscreens
Pitot static probes
Engine intakes
Propellers
Windscreen ice protection req
Front windscreen is electrically heated
Must be serviceable otherwise cannot fly
Used to reinforce the structural strength
Ice detector system purpose
Used to detect build up of ice and signal to flight deck
Does not automatically activate
Windscreen are heated to what
Controlled to heat at 35 degrees
Rain repellent system
Toxic so caution
Used with conjunction with wipers
Can obscure for 15 seconds after being applied
Rose mount Ice detector
Probe mounted on vibrator house which vibrates at 40hz when no icing when ice accumulates frequency decreases which indicates a light warning in the cockpit
Ice detection - Advisory
Crew activate ice protection based on flight manual
Primary Ice detection system
Automatically activates ice protection systems at optimal moment.
Windshield ice control
Electrically heated via small wires in panel. AC current to produce heat
Differential Pressure Ice detector
Hollow tubes on LE and TE detector monitors pressure difference between the two. In icing condition hollow tubes become blocked by ice causing pressure difference. Heater element around heats up holes causing indications to turn off
Hot Rod Detector
Unit mounted outside cockpit window ice builds up on leading edge of probe
Can be decided to observe icing conditions
Hydrophobic seal coatings
Ensures rain beads up and falls of naturally providing pilot with enhanced visibility in wet conditions. Added by manufacturer
Last longer than chemical
How does rain repellent coating work on windscreen?
The water forms beads which roll of the screen
Forms large water droplets to fall off naturally
Is not applied to dry window screen though
Large transport airplanes use what to anti ice
A hot air thermal system
Bleeding air from the later stages of compressor
