Fuel System Flashcards
How many integral fuel tanks does the T-6 use?
3
Approximately how much fuel does the T-6 hold?
1100 pounds of usable fuel
What are the two ways the T-6 can be refueled?
Single point and over the wing
Where is the single point refueling port?
On the left front fuselage
What kind of system is the fuel system?
Motive flow
What is motive flow?
As fuel moves through the lines, it creates a pressure differential between the fuel lines and fuel tanks. This causes a lower static pressure in the fuel lines and “siphons” fuel from the tanks
What does the electric boost pump do?
Provides fuel to the engine during startup or in case of failure of the engine driven low-pressure fuel pump
Where is the flip flop valve located?
The central collector tank
What does the flip flop valve do?
Supplies fuel feed during negative-G flight operations
What maintains fuel balance between the wings?
An auto-balancing system
What are the three fuel tanks called?
- Left wing
- Collector tank
- Right wing
What are the two fuel pumps?
- Engine-driven low pressure pump
- Engine-driven high pressure pump
How much fuel does each wing tank hold?
Approximately 530 lbs of fuel
How much fuel does the collector tank hold?
Approximately 40 lbs of fuel
What is the primary method of refueling?
Single point refueling
During single point refueling, how do the wing tanks fill?
Simultaneously
If empty, how does the collector tank receive fuel?
A gravity feed from the wing tanks
How long does it take to refuel the T-6 using single point?
3-5 minutes
How is refueling stopped once full?
Level control pilot valves
Where are the level control pilot valves located at?
The outboard tip of each wing
How do the level control pilot valves operate?
When fuel reaches the valves, which in turn causes the level control shutoff valves to close, halting fuel flow
How long does it take to defuel the T-6?
Approximately 5 minutes
What is the secondary method of refueling?
Over the wing gravity refueling
Where are the two ports for over the wing refueling?
One on top of each wing tank
If using over the wing refueling, how much extra fuel can be added to the tanks?
50 lbs per tank, 100 lbs total
What are two restrictions to the over the wing method?
There is no automatic shutoff, and the system can’t be defueled from the over wing ports
What does the electric boost pump do?
- Provides fuel delivery for initial engine startups
- Also acts as a backup to the engine-driven low pressure pump
What does the manifold valve do?
Connects the electric boost pump and primary jet pump to the engine feed line
Where is the manifold valve located at?
The front of the collector tank
What component does fuel travel to after the collector tank?
The fuel filter
What does the fuel filter do?
Prevents contaminates from reaching the main fuel pumps or engine
What is the fuel filter equipped with?
Fuel bypass
What does the fuel bypass do?
Enables fuel flow to the engine if the fuel filter becomes restricted
What two valves are located in the engine feed line?
- Firewall shutoff valve
- maintenance shutoff valve
What is the purpose of the firewall shutoff valve?
- Stops fuel flow to the engine
- Actuated by Firewall Shutoff Handle
What is the purpose of the maintenance shutoff valve?
Isolates the fuel system for engine or fuel filter maintenance
Where does fuel travel after the fuel filter?
The engine-driven low pressure fuel pump
Where does fuel travel after the engine-driven low pressure fuel pump?
The engine-driven high pressure fuel pump, based on engine requirements
Where does fuel travel after the engine-driven high pressure fuel pump?
The FMU, which controls fuel delivery to the engine
What transmitter is tripped after the engine-driven high pressure fuel pump?
The fuel flow transmitter
What does the fuel flow transmitter send a signal to?
The AEDD, indicating fuel flow
What happens to any fuel that’s not used by the engine?
Sent from the engine-driven high pressure fuel pump through a purge line back to the collector tank
Why is some fuel routed from the low pressure fuel pump through the motive fuel line?
Powers the primary and transfer jet pumps
What switch is located in the motive flow line?
10 psi low pressure switch
What happens if low pressure in the motive flow line falls below 10 psi and the PCL is above the start ready position?
- The electric boost pump is activated
- FUEL PX annunciator is illuminated
What does the primary jet pump do?
Delivers fuel from the collector tank to the low pressure fuel pump
What do the transfer jet pumps do?
Direct fuel from the wing tanks to the collector tank. This keeps the collector tank pressurized
What concept causes the primary and transfer jet pumps to operate?
Venturi flow
How many fuel level probes are there?
7
Where are the fuel level probes located?
3 in each wing and 1 in the collector tank
Where do the fuel level probes send a signal to?
AEDD for fuel quantity
Where are the fuel low level sensors located?
Rear edge of the inboard ends of the wing tanks
What do the fuel low level sensors do when fuel is low?
Illuminate L FUEL LO or R FUEL LO annunciators
How much fuel illuminates a L or R FUEL LO annunciator?
110 pounds
What is a normal fuel flow readout during cruise flight?
350 Pounds Per Hour (PPH)
What causes the FUEL BAL annunciator to illuminate?
- Indicates a fuel imbalance of 30 lbs or more for more than 2 minutes, and auto balancing system hasn’t corrected the problem
- Also illuminates if a fuel probe has failed
- Will remain illuminated until fuel system is reset
What causes M FUEL BAL annunciator to illuminate?
Anytime the fuel balance switch is NOT in the AUTO position
What is the purpose of the vent lines?
Provide vacuum and pressure relief for the wing tanks
How are the wing tanks internally vented to each other?
Cross vent line
What is the purpose of the float valve?
If the aircraft is parked on a sloped surface, the float valve keeps fuel from draining on the lower wing
What does balance the fuel balance system maintain?
Within 20 lbs
