Ice and Rain Protection

Question 1

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?

Answer 1

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

Question 2

Describe the “ICE DETECTED” messages

Answer 2

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.

Question 3

What is the increment on Vref with the “Inc ref speed” switch on?

When do you turn it on?

Answer 3

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.

Question 4

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?

Answer 4

18 +/- 3psi

15 psi. Green boot inflation lights.

When you get AC power (condition leavers max)

Question 5

Describe the deicing sequence by the TMU and dwell time.

How many cycles?

How long is each cycle

Answer 5

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.

Question 6

Hoe long is a prop deice cycle to test?

What are the temp limits and what is the min RPM?

Answer 6

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.

Question 7

What is the temperature limit for use of windshiled heat?

Describe the test

Answer 7

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.

Question 8

When are the deicing doors opened?

When must they be closed?

Answer 8

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.

Question 9

If the AOA heaters fail, which caution lights come on?

Answer 9

PUSHER SYST FAIL and related stall syst fail.

Question 10

What is the indication of a leak in the pneumatic deice system?

Answer 10

“LOW DEICE PRES” caution light and it comes on at ,15 psi

Question 11

How long is a prop deice cycle?

When does the TMCU heat all six blades on one propeller?

Answer 11

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.

Question 12

What is required for “ICE DETECT FAIL” caution lights.

Answer 12

Both ice detector probes fail. If one comes on, then maintenance gets a fault message.

Question 13

What is the pressure source for the deicing boots?

Answer 13

Low pressure bleed air (NL)

Question 14

What is the purpose of the ISO valve?

Answer 14

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.

Question 15

What does the manual position of the Airframe Mode Select do?

Answer 15

Heaters for the DDV and check valve are manually opened permanently.

Question 16

When do the integral DDV and check valve heaters automatically come on?

When are they on permanently?

Answer 16

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.

Question 17

What happens if you shut down an engine with the prop deice running?

Answer 17

“PROP DEICE” caution light comes on.

Question 18

How can you increase the efficiency of prop deicing if you are building ice rapidly?

Answer 18

Condition leavers max

Question 19

Does airframe de-ice work with the bleeds off?

Answer 19

Yes

Question 20

What happens if the TMU temperature monitoring parameter fails?

What happens if the TMU heater activation parameter fails?

Answer 20

Valve heaters stay on by default.

Valve heaters will not come on automatically.

Question 21

What happens when you turn on the Alternate Wiper Switch light?

Answer 21

Turns wipers on high speed only.

Question 22

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?

Answer 22

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.

Question 23

What does the de ice pres gauges normally indicate?

What do they indicate when in ISO mode?

Answer 23

Average de-ice pressure on both sides.

Deice pressure on the indicated side as it is isolated.

Question 24

When does the heat for the ice detection probes automatically turn on?

Answer 24

When ice is detected.

Question 25

What is required if the boot isolation valve is closed?

Answer 25

Manual operation of the boots.

Question 26

When operating the boots manually, how long do the boots stay inflated?

Answer 26

For as long as the switch is in the given position. Therefore operator has to control of timing.

Question 27

What causes the “DEICE PRES” caution light to illuminate?

Answer 27

• 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).

Question 28

What is required for the “WSHLD HOT” or “ SIDE WDO HOT” caution light to come on?

Answer 28

Over heat temperature of 50 +/-3 degrees Celsius.

Question 29

Which pitot static probes use DC power to run their heaters?

Answer 29

Standby probe only.