Fuel System Flashcards
Total capacity of tanks? Gals/lbs
1028 Gals, about 6900-7000 lbs
Why are fuel capacities different in each tank?
Fuel quantities in each tank are different due to the placement of the filler caps in each of the tanks.
How many fuel quantity probes and where are they located?
10
3 in each main tank and 1 in each aux tank.
How many fuel tank boost pumps?
8
2 in each main and 1 in each aux
Which tanks do the heater and apu run off of?
Heater runs off of right main and APU off of left main
How many gallons per minute can the pressure refueling accept and at what psi?
The pressure refueling system allows the helicopter to be completely refueled in about 4 minutes with fuel supplied at 300 Gallons Per Minute (GPM) at 55 PSI.
Where is the crossfeed fuel line located?
Located overhead at station 504 (x feed fuel shutoffs also located at station 504 )
What do the fuel tanks do in a crash?
The mounting bolts of the fuel cell shear off and allow the pods to separate from the aircraft .
Also, the fuel pod cell is self sealing.
Can the pilot tell if there is a hole in the fuel pod bladder?
If the self sealing chemical is inadvertently activated and not noticed by maintenance personnel, the pilot will not notice any change in fuel quantity due to the design of the fuel quantity indicating system.
What prevents fuel from spilling in the event of a rollover?
The tank venting system.
There are primary and alternate fuel vents. Where are they located
The primary vents are float/drain valve assemblies installed on the bottom aft end of each pod that also work to seal the drains in the case of a water landing.
The alternate fuel vents are the high vent pipes on the top of each tube (covered by the screen).
Will the vents prevent main tank over pressurization from over filling?
The vent system is NOT capable to keep up with the fuel pumps if the high level shutoff valves fail. This situation will result in main tank over-pressurization.
What PSI do the in tank boost pumps supply?
At least 22 psi
What are the functions of the main and aux boost pumps?
The main pumps provide positive fuel pressure to the engines. The aux pumps purpose is to transfer fuel to the main tanks.
The forward pumps in the main tanks are also used to evacuate the pressure refueling manifolds and crossover line through the operation of the jet pumps.
What is the purpose of the bell mouth fitting?
To draw fuel out of the main tank via the ENGINE driven fuel pump when the main tank fuel pump(s) fail.
What is the purpose of the jet pump?
To evacuate the fuel from the pressure refueling system using a Venturi type system (main tank boost pump pressure creates little vacuum to suck fuel out of line and spit it in main tank.
Are all fuel lines self sealing?
No-pressure refueling line is not self sealing.
What type of fuel probes are used?
Capacitance type. The capacitance changes as the fuel level in the tank changes.
What illuminates the fuel level lights?
When approximately 20% of fuel is remaining 320 to 420 Lbs, the thermistor control unit illuminates the ―L FUEL LVL‖ or ―R FUEL LVL‖ low caution lights.
Is there a physical connection between the fuel quantity indicator and fuel level probes?
No. They are Electrically connected to the cockpit fuel quantity indicator.
At what PSI do fuel pump lights come on?
10 PSI
Indicates that the pump has failed or the tank is empty.
What is the function of the (main) fuel pump relay and where are they located?
The function of each relay is to control application of AC power to the pumps.
Located in the cabin at station 340 on left and right sides.
How does electricity get from the boost pump switch on the control panel to the boost pump?
All of the boost pump relays are controlled by the fuel pump switches with 28 VDC. Each relay supplies its respective pump with 115 VAC, three phase, for operation.
How are the auxiliary boost pumps relays different?
The auxiliary pump relays are controlled by thermistor control units, mounted externally on the top of each (main boost pump) relay box, and two thermistors mounted on each auxiliary pump mounting bracket.
When an auxiliary tank empties, and the thermistors on that pump mounting bracket become uncovered, DC power is interrupted to the pump relay through the thermistor control unit. This in turn removes AC power from the pump. In order for the pump to turn on again, fuel must cover both thermistors on the pump mount bracket