Learjet 35 PTM Chapter 10 (Ice Protection)

Question 1

What are the electrically heated components?

Answer 1

Pitot Tubes
Static Ports
Pt2/Tt2 sensors
Stall Warning Vanes
TAT Probe

Question 2

Icing conditions in the air vs ground temperatures:

Answer 2

Ground: +4.4 C or below
Air: +10 C or below

Question 3

If you are in icing conditions and you have a full electrical failure, or you induce electrical failure to save the batteries, will you lose NAC HEAT?

Answer 3

No, the NAC HEAT Shut off valves are energized closed/ deenergized open

Question 4

If testing the NAC HEAT on the ground and it does not come on, increase the power on the engine to at least ____ % N1

Answer 4

At 60% N1, The shut off valve must be open.

Question 5

How do we know if the spinner is heated?

Answer 5

If it is dome shaped

Question 6

What does an ENG ICE light with the associated NAC HEAT switch on indicate?

Answer 6

That bleed air pressure to either the fan spinner or to the nacelle lip is NOT sufficient to provide satisfactory anti-icing protection.

However, when turning the NAC HEAT switch on or off, the respective ENG ICE light illuminates momentarily until bleed air pressure becomes sufficient.

Question 7

What if my NAC HEAT switches are OFF, and I get an ENG ICE light - what is the issue and what can I do?

Answer 7

The issue is that there is bleed air pressure in that part of the system. Cycling the NAC HEAT switch ON and back to OFF may close the open valve.

Question 8

What does the IN-NORMAL/OUT-DEFOG knob control?

Answer 8

That controls a valve that directs bleed-air either to the windshield or to the foot warmers.

Question 9

When do you use the OUT-DEFOG position on the IN-NORMAL/OUT-DEFOG knob?

Answer 9

When you need hot bleed-air to be directed externally for windshield anti-icing.

Question 10

What position does the IN-NORMAL / OUT-DEFOG knob go during emergency pressurization?

Answer 10

IN-NORMAL (Push it in)

Question 11

What does it mean if the red WSHLD OV HT light and green WSHLD HT are both illuminated? And what can we do to fix the problem?

Answer 11

• The high temperature limit has been reached and the pressure regulator valve has closed.
• Turn the windshield heat off. This closes the control valve and shuts off bleed air to the windshield.

Question 12

What is the windshield defog system?

Answer 12

• A gold filament in the windshield is heated - defogging the windshield
• uses 163 VAC
• AUX inverter powers left side
• SEC inverter powers right side

Question 13

What causes the ALC AI light to come on? (Older Serial #s vs Newer Serial #s)

Answer 13

Older: A low pressure switch will actuate and illuminate the ALC AI caution light if the supply of methyl alcohol is depleted. (You will only know you don’t have enough alcohol in the tank once you try and use it!!!) Be careful!
Newer: The float switch in the reservoir illuminates the ALC AI light when the reservoir reads empty.

Question 14

Is the alcohol anti-ice system operational if the emergency pressurization valves are in emergency?

Answer 14

Yes

Question 15

If we lose DC power, do we lose STAB WING HEAT?

Answer 15

Yes. EMER PRESS valve activates, sending the bleed air directly into the cabin - bypassing the Bleed Air Manifold