Ice & Rain Protection Flashcards
How do the Ice Detection Probes work?
They are heated and powered by the 115 volt AC system.
The operate on the piezoelectric principle where the constantly vibrate at a known frequency. When ice accumulates on the probe they become stiffer and the frequency increases.
Takes more than 0.5mm of ice to display ICE DETECT on the ED.
When will we get an ICE DETECT FAIL message?
Only if BOTH probes fail.
How does the airframe deicing system work?
Inflatable boots on the leading edges of the wings, vertical and horizontal stabilizers and the engine intake lips are power by bleed air from the engines. This pressure is regulated to 18 psi.
6 dual distrubter valves (DDV) are controlled by the Timer Monitor Unit (TMU) to maintain a programmed sequence and schedule.
What does the BOOT AIR switch do?
When in the NORM position the valve is open and connected.
When directed by the QRH to test for a leak or to isolate the system the ISO position of the switch closes the valve and splits the system into separate left and right systems.
What do the four positions of the Airframe Mode Selector switch do?
MANUAL - the DDVs are heated and the crew can command which boots are inflated manually.
OFF- the DDVs will only heat below 5C.
SLOW - the DDVs will only heat below 5C and the boots automatically inflate and deflate on a 180 second cycle.
FAST - the DDVs will only heat below 5C and the boots automatically inflate and deflate on a 60 second cycle.
How does the propeller heat system work?
The system is power by the respective 115 volt AC buses.
When the system is turned on all six blades are heated at once. A Timer Monitor Control Unit monitors and controls the system.
When will the propeller heat system activate?
- Switch in the on position
- SAT below 5C
- Propeller speed greater than 400rpm
- AC power available
How are the Pitot Static probes heated?
#1 and #2 probes are powered by the onside AC bus. #3 probe is heated by the Right 28v Essential bus.
How are the engine intakes protected?
The nacele lips have inflating boots and the Engine Intake Heat and Bypass Doors have two heated elements in the intake flange powered by the 115v AC system.
When will Engine Intake Heat activate?
Engine intake doors selected open
Engine is running (oil pressure)
SAT below 15C
115v AC is available
When will the ENG ADPT HEAT 1 CWP light illuminate?
Only if both heating elements fail.
How are the windshields protected from ice buildup?
The left and right windshields are equipped with AC power heaters. They are powered by their respective 115v AC buses.
The captain’s side window is also heated and powered by the right 115v AC bus.
Do we ever use the WARM UP mode?
Only when directed to do so by the QRH.
How are the wipers controlled?
The wipers are controlled by a four position switch on the overhead.
The captain’s side wiper can also be activated in high speed only by the ALTERNATE PILOT WIPER switchlight on the captain’s side panel.
How are the AoA Vanes heated?
By their respective 115v AC buses.
A failure of the heater in the AoA Vane will result in the illumination of the PUSHER SYST FAIL and #_ STALL SYST FAIL CWP lights.
