Air Systems

Question 1

WING–BODY OVERHEAT Light - what is the difference between the left and the right light?

Answer 1

Left light indicates also overheat from keel beam and APU bleed air duct.
(FCOM 2.10.2)

Question 2

What is the function of the TRIP RESET pushbutton?

Answer 2

Resets BLEED TRIP OFF, PACK or ZONE TEMP lights.

FCOM 2.10.2

Question 3

ZONE TEMP light FWD CAB or AFT CAB - what is the difference between illumination of the light and illumination during master caution recall?

Answer 3

Illumination: indicates duct temperature overheat.
Illumination during recall: indicates failure of the associated zone temperature control.
(FCOM 2.10.5)

Question 4

Recirculation fans - what is the AUTO mode logic inflight and on the ground?

Answer 4

On the ground:
Right: works always;
Left: works unless both packs are in HIGH.
Inflight:
Right: works if both packs are operating, unless both packs are in HIGH;
Left: works if both packs are operating, unless either pack is in HIGH.
(FCOM 2.10.6)

Question 5

Which systems rely on the bleed air for operation?

Answer 5

The following systems rely on the bleed air system for operation:
1. Air conditioning/pressurization;
2. Wing and engine thermal anti-icing;
3. Engine starting;
4 Hydraulic reservoirs pressurization;
5. Water tank pressurization;
6. Aspirated TAT probe.  
(FCOM 2.20.1)

Question 6

DUAL BLEED Light - conditions for illumination.

Answer 6

The DUAL BLEED light illuminates whenever the APU bleed air valve is open and the position of the engine bleed air switches and isolation valve would permit possible backpressure of the APU.
(FCOM 2.20.2)

Question 7

Automatic switching of the packs to high air flow - when it is inhibited? What happens if the engine bleeds are off and the APU bleed supplies the bleed air for the packs?

Answer 7

Automatic switching is inhibited when the airplane is on the ground, or inflight with the flaps extended. When engine bleed air switches are OFF and the APU bleed air switch is ON, automatic switching occurs regardless of flap position, air/ground status or number of packs operating.
(FCOM 2.31.1)

Question 8

What happens if both the primary and the standby pack controls fail for the same pack?

Answer 8

The pack will continue to operate without control unless excessive temperatures cause the pack to trip off.
(FCOM 2.31.2)

Question 9

Which switch shuts off the AC power to the recirculation fans?

Answer 9

CAB/UTIL.

FCOM 2.31.6

Question 10

How is the forward cargo compartment heated?

Answer 10

The recirculation fan system circulates air from the passenger cabin around the lining of the forward cargo compartment. When the overboard exhaust valve is closed, exhaust air from the equipment cooling system is also diffused to the lining of the forward cargo compartment for additional inflight heating.
(FCOM 2.31.6)

Question 11

What are the differential pressure limits for the different flight altitudes?

Answer 11

At or below 28,000 feet - 7.45 psid
28,000 feet to 37,000 feet - 7.80 psid
Above 37,000 feet - 8.35 psid
At max differential pressure of 9.1 psi the pressure relief valves are relieved. 
(FCOM 2.40.5)

Question 12

Conditions for AUTO FAIL light.

Answer 12

An amber AUTO FAIL light illuminates if any of the following conditions occurs:
1. Loss of DC power;
2. Controller fault;
3. Outflow valve control fault;
4. Excessive differential pressure (> 8.75 psi);
5. Excessive rate of cabin pressure change (±2000 sea level feet/minute);
6. High cabin altitude (above 15,800 feet).
(FCOM 2.40.5)