AMS: Pneumatic, ECS and Pressurization

Question 1

for a/c to be on, what must be TRUE?

Answer 1

either GPU or one engine running

Question 2

max diff cabin pressurization vs. outside

Answer 2

9.4 psi

Question 3

max diff overpressure for cabin vs. outside

Answer 3

9.6 psi

Question 4

max diff negative pressure (vs. outside)

Answer 4

-0.3 psi

Question 5

max diff pressurization for T/O and LDG

Answer 5

0.2 psi

Question 6

What TWO systems comprise the interconnected pneumatic system?

Answer 6

• ECS (Enviro Control Sys)
• WHHAIS (Wing and Horiz. Stab. Anti-Ice System)

*circuits are interconnected or segregated by XBV (Cross Bleed Valve)

Question 7

what is key valve for bleed system?

Answer 7

the PRSOV - the pressure regulating shutoff valves

Question 8

what happens to the PRSOV during OEI take off?

Answer 8

the PRSOV automatically closes

Question 9

FAN (fan air valve) does what?

Answer 9

it is regulated by the pneumatic system to maintain desired bleed air temperature

Question 10

Describe bleed air from engines to use in ECS as if you were a molecule in the air stream:

Answer 10

bypass air coming through FAV pre-cools the bleed air that can go one of two ways:
#1 to anti-ice functions (cooled a bit via FAV)
#2 to heat exchanger where it is cool by ram air or ground a/c (VCS) by ground fan during ground ops

Question 11

ECS consists of? (6 systems)

Answer 11

• BLEED air inflow (pneumatic system)
• TEMP control system (TCS)
• VAPOR (A/C) cycle air conditioning system (VCS)
• AIR distribution ducting system
• EMERGENCY ventilation system
• FRESH air supply system (on ground)

Question 12

What is one input for pressurization system crew must put in prior to departure?

Answer 12

LFE

Question 13

What will DUMP button do? (2 things & a condition)

Answer 13

When pressed, it will:

a) open the outflow valve
b) turn off recirculating fans

** The outflow valve will open until a cabin altitude of 14,500 (?) is reached.

Question 14

what is a pneumatic limitation above 30,000 feet?

Answer 14

the airplane cannot de-ice and pressurize the cabin at same time