Lear 45 TCAS Pneumatics

Question 1

Where are the bleed air shut off valves (ECS PRSOV)?

Answer 1

In the tail cone area. (Environmental Control System Pressure Regulating and Shut Off Valve)

Question 2

In what position do the following valves fail in the event of total electrical failure (including no battery power)?

1. ECS PRSOV
2. HP SOV
3. EMER PRESS valve

Answer 2

1. ECS PRSOV (LP bleed) - fails open - in other words if the power fails the ECS will just pump out cold 37º air.
2. HP SOV - fails to closed position - good because when open it pumps out dangerously hot air that can start fires
3. EMER PRESS - Fails closed - good because if it failed open it would pump out a lot of hot air.

Question 3

What are the two scenarios that will cause the ECS PRSOV (LP bleed) valves to close?

Answer 3

1. When there is an engine fire and the Fire wall valves are closed.
2. When the emergency pressurization system is activated. (LP bleed air will bypass the ECS)

Question 4

Does the HP SOV open on the ground?

Answer 4

Yes, when the engines are at idle to provide adequate heating and cooling.

Question 5

At what temperature will a left or right PYLON OVHT red message come on the CAS

Answer 5

At 250º

Question 6

At what temp will a BLEED OVHT come on

Answer 6

When the temp of the HP bleed air exceeds 700º.

Question 7

At what temperature will the BLEED AIR LEAK message come on? Where does it occur

Answer 7

At 255º in the tail cone.

Question 8

Can the crew turn on the emergency pressurization system if there is no power?

Answer 8

Nope. The emergency press valve fails closed.

Question 9

If emergency pressurization is activated does the crew still have Wing and Stab heat?

Answer 9

Yes.