Pneumatics/AirCon

Question 1

2 Sources of Bleed Air?

Answer 1

Engine Bleed Air (from LP compressor, but supplemented as required by HP compressor)
APU Bleed Air (capable of providing all B/A on the ground).

Question 2

Components (Big List)

Answer 2

• Pre cooler with removable bypass sections
• 2 high pressure switches
• high pressure shutoff valve
• choking venturi
• low pressure check valve
• nacelle shutoff valve
• duct overpressure switch

Question 3

Pre-Cooler

Answer 3

Cools air to a good temp for A/C packs, is bypassed when not required.
Is a steel heat exchanger in the HP B/A port.

Question 4

Dash - 300 - High Pressure Switch Information

Answer 4

• 2 normally closed switches in the HP outlet duct.
• No1 is 65 PSI, for ground OPs (also active when Airframe Auto DeIce is active).
• No2 is 55 PSI, for flying.

Question 5

Dash - 300 - Nacelle Shutoff Valve

Answer 5

When an overtemp occurs the Nacelle Shutoff Valve closes on the Dash 300.

Question 6

What pressure sets off the wing bleed overpressure switch?

Answer 6

If B/A >75 PSI, the switch closes the nacelle shutoff valve in the effected wing.

Question 7

What temperature signals “Bleed Hot” caution light?

Answer 7

> 290 degrees. (Somewhere 287 written, pretty close…)

Question 8

In the 100, what is the proportion of Air Con to Cabin VS Cockpit

Answer 8

70/30 (favouring cabin due larger size)

Question 9

Why should recirc fans be on?

Answer 9

Helps cool avionics.

Question 10

What signals “Duct Hot” warning light?

Answer 10

Duct temperature >88 degrees (when temp drops below 82 it cancels).

Question 11

“Air Conditioning Pack Hot” Trigger Temp?

Answer 11

207 degrees. Hot air supply is cut off, therefore pressurisation in the 100 will not be working…