Fuel System

Question 1

Where is fuel stored?

Answer 1

In wing tanks that are part of internal wing structure:
there are no bladders.
Ref: AOM 2A

Question 2

Describe location and capacity of
hopper tanks.

Answer 2

Inside each wing tank, adjacent to centerline rib, is a
hopper that holds approximately 190 gallons of fuel.
Ref: AOM 2A

Question 3

What’s the purpose of ventilation
system?

Answer 3

It protects from over and under pressurization by
allowing air, fuel vapors, and fuel to move about or
flow freely.
Ref: AOM 2A

Question 4

Vent tubes are connected to an
empty chamber or plenum which is
located at wing tip, just outboard of
the fuel tanks. What’s the capacity
of plenum and vent tubes?

Answer 4

They provide for 2% fuel expansion
Ref: AOM 2A

Question 5

What’s indicated if the red light
illuminates on refuel panel?

Answer 5

High level sensors are wet and Fuel Quantity Signal
Conditioner (FQSC) has closed the respective refueling
valve
Ref: AOM 2A

Question 6

What happens when REMOTE
FUELING SHUTOFF switch is

selected to CLSD?

Answer 6

Both pressure fueling shutoff valves close and CLSD
legend illuminates in blue
Ref: AOM 2A

Question 7

What are the different methods of
refueling?

Answer 7

Single point pressure fueling or over-the-wing
Ref: AOM 2A

Question 8

How is automatic refueling
controlled?

Answer 8

Via Standby Multifunction Controller (SMC) or refuel
panel located at fueling station.
Ref: AOM 2A

Question 9

How many methods are there for
maintaining fuel balance?

Answer 9

Two: by moving fuel from hopper to hopper through
intertank valve, or by directing fuel from one hopper to
opposite engine using crossflow valve.
Ref: AOM 2A

Question 10

How many boost pumps does G650
have and where are they located?

Answer 10

There are four (4) identical and interchangeable fuel
boost pumps in the main wheel wells attached to aft
portion of each hopper.
Ref: AOM 2A

Question 11

What’s the purpose of fuel boost
pumps?

Answer 11

They deliver fuel to engines and APU at relatively low
pressure through various fuel distribution lines and
shutoff valves.
Ref: AOM 2A

Question 12

How does fuel flow into the
hopper?

Answer 12

Ejector pumps and three one way flapper type
check valves

Ref: AOM 2A

Question 13

How do ejectors operate?

Answer 13

They require only fuel boost pump pressure to operate:
they’re low pressure, high volume jet pumps. As long
as there’s boost pump pressure, ejector pumps deliver
steady flow of fuel into each hopper.
Ref: AOM 2A

Question 14

What happens when crossflow
valve is opened?

Answer 14

Boost pump manifolds are joined allowing pressurized
fuel from functioning pumps to flow to both engines.
Ref: AOM 2A

Question 15

When does the color of blue Fuel
Crossflow Valve Open message
change to amber?

Answer 15

After five (5) minutes
Ref: AOM 2A

Question 16

What’s the warning associated with
use of crossflow valve?

Answer 16

Always OPEN crossflow valve before turning OFF
both boost pumps on one side. Without boosted
pressure above 20,000’, Gulfstream says the engine will
run erratically and flameout.
Ref: AOM 2A

Question 17

What happens when intertank valve
is opened?

Answer 17

Fuel can gravity flow between the two hopper tanks
allowing the tanks to balance.
Ref: AOM 2A

Question 18

What action does Gulfstream
recommend before opening the
intertank valve?

Answer 18

Establish a sideslip (i.e., rudder trim in direction of
heavy tank)
Ref: QRH

Question 19

What happens when FUEL
RETURN switch is selected to
AUTO?

Answer 19

OFF caption extinguishes and the system allows heated
fuel into the tanks when fuel tank temperature is
approximately 0°C or colder. When tank temperatures
warm to approximately +10°C, heated fuel stops
flowing to the tanks.
Ref: AOM 2A

Question 20

There are several abnormal
conditions which inhibit the heated
fuel return system from operating
(e.g., fire handle pulled, low fuel
pressure signal, low fuel quantity
signal). What types of normal
conditions inhibit this system from
operating?

Answer 20

Crossflow valve open or engine at high power setting
Ref: AOM 2A