OBIGGS System

Question 1

Oxygen limit in fuel tanks?

Answer 1

9%

Question 2

Secondary purpose of OBIGGS?

Answer 2

Aux fuel transfer

Question 3

Primary purpose of OBIGGS?

Answer 3

Prevent combustion

Question 4

OBIGGS in the descent?

Answer 4

Aux fuel nitrogen air forced to main/center tank with valve prevent back flow. If over 500 fpm, high flow

Question 5

Nitrogen Air Source

Answer 5

Bleed system crossover manifold to ozone Converter

Question 6

Whats required before OBIGGS selection?

Answer 6

Fuel system preflight/AAR Preflight

Question 7

Modes

Answer 7

Standby - No bleed air, controller is ready to begin flow
Low - Optimize bleed air consumption, used to inert when aft aux tank has over 12,000 lbs of fuel to prevent over inerting
Mid - Used in most flight situations and inerting on ground. Warms up in mid flow if aft aux tank has over 12,000 lbs
High - Isolates the aux fuel and only supplies to Main and Center

Question 8

Requirements for Ground Operation

Answer 8

APU or Bleed air on
Pack in Auto or High (should be both but if OAT is less than or equal to 10 degrees C then only use one)
Both Engine Start Switches in Auto
Should have recirculation fans on

Question 9

What happens if OBIGGS isnt inerted before takeoff?

Answer 9

Goes into flight mode
Mid Flow
OBIGGS O2 High caution at approximately 80-100 knots

Question 10

How long can the engine start switches not be in auto or the packs not in in auto/high before failure?

Answer 10

40 minutes

Question 11

What will degrade OBIGGS inerting process on the ground?

Answer 11

Wing Anti-ice operation