Ice and Rain Protection Flashcards
How is ice prevented from forming on the intake flanges? What temperature?
How is ice prevented from forming on the aft part of the air intake flange?
Two electrical heaters, a primary and a secondary. If the primary fails, the secondary works and there is no indication.
Temperature has to be less than 15°C. Intake bypass doors must be opened, oil pressure in related engine, and AC power available.
Hot oil flowing through internal passages
Describe the “ICE DETECTED” messages
Ice forms on vanes on both sides of the forward fuselage. This changes the vibration frequency.
Yellow, flashing “ICE DETECTED” message means “Inc ref speed” switch is off. it turns to flashing white when you turn on the “Inc ref speed” switch on and stops flashing when you turn on the boots.
What is the increment on Vref with the “Inc ref speed” switch on?
When do you turn it on?
20 kts, flaps 35° 15 kts
You turn on in icing conditions when you’ve reach your increment. i.e. Vclimb + 20 (Vclimb ice). You also turn it on prior to entering visible moisture when the temperature is +5°C or colder or anytime you get an “ICE DETECTED” message.
What is the normal de-ice pressure?
What is the min pres to inflate boots? Apart from the de-ice pres gauge, what is the other indication that the system has reached system pressure?
When do alpha vanes get heated?
18 +/- 3psi
15 psi. Green boot inflation lights.
When you get AC power (condition leavers max)
Describe the deicing sequence by the TMU and dwell time.
How many cycles?
How long is each cycle
Fast: 1 min. 36 seconds, 24 seconds dwell time
Slow: 3 min. 36 seconds, 2:24 dwell time
There are 6 cycles and each lasts for 6 seconds.
Hoe long is a prop deice cycle to test?
What are the temp limits and what is the min RPM?
7 seconds per prop, min 30 seconds wait time.
5°C or less and 400 RPM
Test can’t be started again for 30 seconds after a test.
What is the temperature limit for use of windshiled heat?
Describe the test
20°C
Turn switch to “Norm” (never warm up). The test lasts for 5 minutes. If no “WINDSHIELD CTRL” caution light then test has passed.
When are the deicing doors opened?
When must they be closed?
Opened prior to entering icing conditions. Can be opened for takeoff.
They must be closed prior to feathering the prop (normally in after landing checks). They must also be closed when doing an MTOP at ISA +25°C or warmer.
If the AOA heaters fail, which caution lights come on?
PUSHER SYST FAIL and related stall syst fail.
What is the indication of a leak in the pneumatic deice system?
“LOW DEICE PRES” caution light and it comes on at ,15 psi
How long is a prop deice cycle?
When does the TMCU heat all six blades on one propeller?
Varies according to TAT and is controlled by the TMCU.
- Prop selector set to on
- TAT is less than or equal to +5°C
- Np is above 400 RPM
- AC power is available.
What is required for “ICE DETECT FAIL” caution lights.
Both ice detector probes fail. If one comes on, then maintenance gets a fault message.
What is the pressure source for the deicing boots?
Low pressure bleed air (NL)
What is the purpose of the ISO valve?
To isolate the left and right bleed systems so a fault can be detected and pressure is available to the operating side. The failed side becomes isolated from the operating side.
What does the manual position of the Airframe Mode Select do?
Heaters for the DDV and check valve are manually opened permanently.
When do the integral DDV and check valve heaters automatically come on?
When are they on permanently?
TMU temperature monitor parameter hasn’t failed. (If temp monitor parameter fails, it still works).
Airframe mode selector set to OFF, SLOW or FAST
SAT less than +5°C
When AIRFRAME MODE SELECT set to manual.
What happens if you shut down an engine with the prop deice running?
“PROP DEICE” caution light comes on.
How can you increase the efficiency of prop deicing if you are building ice rapidly?
Condition leavers max
Does airframe de-ice work with the bleeds off?
Yes
What happens if the TMU temperature monitoring parameter fails?
What happens if the TMU heater activation parameter fails?
Valve heaters stay on by default.
Valve heaters will not come on automatically.
What happens when you turn on the Alternate Wiper Switch light?
Turns wipers on high speed only.
At what temperature does the engine adapter heater work?
How many temperature sensors and where are they?
What can happen if the temperature is close to the activating temperature?
15 degrees Celsius.
2 sensors on lower fuselage close to the nose.
They may or may not work. Only worry about failure if the “ENG ADAPT HEAT” caution light comes on.
What does the de ice pres gauges normally indicate?
What do they indicate when in ISO mode?
Average de-ice pressure on both sides.
Deice pressure on the indicated side as it is isolated.
When does the heat for the ice detection probes automatically turn on?
When ice is detected.
What is required if the boot isolation valve is closed?
Manual operation of the boots.
When operating the boots manually, how long do the boots stay inflated?
For as long as the switch is in the given position. Therefore operator has to control of timing.
What causes the “DEICE PRES” caution light to illuminate?
- If boots don’t fully expand after opening of a DDV (leak failure).
- Boots remain inflated after the DDV closes (valve malfunction not allowing deflation).
What is required for the “WSHLD HOT” or “ SIDE WDO HOT” caution light to come on?
Over heat temperature of 50 +/-3 degrees Celsius.
Which pitot static probes use DC power to run their heaters?
Standby probe only.
