17. Miscellaneous Systems

Question 1

Why must PULL ON-SYS READY handle be pulled out to arm oxygen system prior to flight?

Answer 1

The oxygen bottle cable or linkage could freeze in OFF position and not be available for flight

Question 2

What is the planned usage/altitude for standard masks and crew diluted-demand masks in SLPM (standard litres per minute) at 100% mode (required above 20000ft)?

Answer 2

At 35000ft:
Standard- 3.9
Diluted-demand- x2

Question 3

What is the difference between Normal, 100% and Emergency oxygen modes?

Answer 3

Normal- mixes cockpit air with oxygen to reduce rate of depletion.

100%- only oxygen.

Emergency- positive pressure (should be used if smoke/fumes present.

Question 4

What causes the passenger manual override shutoff valve to open? And what else happens with this?

Answer 4

Anytime cabin pressure exceeds approx 12500ft

• PASS OXY ON annunciator lights up
• Cabin lights go on full bright
• Passenger masks drop down

Question 5

How can passenger oxygen be shut off above 12500ft cabin altitude?

Answer 5

Pulling oxygen control circuit breaker.

This will isolate oxygen for crew and first aid outlets