Fuel System Flashcards
Trapped fuel weight:
Is included in the aircraft basic weight for airplanes certified in the U.S.
With exception of the FUEL JTSN lights, all other Amber lights on the fuel control panel, when illuminated steady, indicate that the respective:
Valve position disagrees with the switch
The red LOW FUEL light illuminates when
400 to 500 lb remains in either wing
The standby pumps are used for all the following functions except:
Wing-to-wing crossflow with a wing tank jet pump inoperative
The crossflow valve opens:
Whenever the CROSS FLOW, XFER-FILL, or FUS VALVE switches are moved from the OFF or CLOSE position
Steady illumination of an amber transfer valve light indicates:
The valve failed to move to the position commanded by the XFER-FILL switch
(i.e. disagreement)
Illumination of the red L or R FUEL PRESS light indicates:
Fuel pressure to the respective engine-driven fuel pump is low
When the XFER-FILL switch is placed to the FILL position, the:
Crossflow valve opens
Motive-flow fuel for the jet pumps is supplied by:
Engine-driven fuel pumps
The amber FUEL Filter light indicates:
That one or both fuel filters are being bypassed
The amount of fuel trapped in the fuselage tank after completion of gravity transfer vis the fuselage valve is approximately:
162 lb (24.3 gallons)
The wing fuel pressure switch:
Turns off the fuselage transfer pump when wing fuel pressure reaches 5 psi
When using any mixture of aviation gasoline:
- Do not take off with fuel temperature lower than -54C (-65F)
- Restrict flights to below 15,000 ft
- Both jet pumps and both standby pumps must be on and the pumps must be operating
The Learjet 35/36 requires anti-icing additive:
At all times
Maximum demonstrated fuel imbalance is:
600 lb tip tanks
Max Usable Fuel
Total:
Fuselage Tank:
Tip Tanks:
Wing Tanks :
Total: 6,238
Fuselage Tank: 1,340
Tip Tanks: 1175 / right and 1215 left - 2390 total
Wing Tanks : 1254 / side - 2508 total
Max Tip tank fuel for landing
925 lbs.
Do not energize fuselage transfer system when
wing and tip tanks are full
Can you cross flow with wing jet pump inoperative?
No, do not do it.
How long does it take to Jettison Full Tip Tanks ?
approximately 5 minutes
Time to reduce from Max takeoff wt. to max. landing weight is approximately:
40 minutes
Max Altitude or suction feed (red FUEL PRESS light illuminated)
25,000 feet.
Refueling Considerations:
Fuel flow for proper PRIST mixing:
Max/Min fuel per 20oz. can of PRIST:
Max Tip Tank imbalance during refueling:
Fuel flow for proper PRIST mixing: 30-60 GPM
Max/Min fuel per 20oz. can of PRIST: (Check Fuel Addenda)
Max Tip Tank imbalance during refueling:
Approximately how much unusable fuel is in the fuselage tank using alternate transfer (gravity method)
162 lbs.
Fuel System Limits:
125 Gallons: 162 lbs. : 200 lbs. : 400-500 lbs. : 500 gallons : 600 lbs. : 600 lbs : 760 lbs. or less : 925 lbs : 13,500 lbs :
125 Gallons: Service per Tip Tank or fill both tanks simultaneously
162 lbs. : trapped fuel in fuselage tank during gravity transfer
200 lbs. : Max lateral fuel imbalance for use of autopilot
400-500 lbs. : Fuel level in either wing tank illuminates red LOW FUEL Light
500 gallons : AVGAS may not be used in excess of 500 gallons per 100 hours of operation per engine
600 lbs. : Max demonstrated fuel imbalance for landing (one tip tank half full the other empty )
600 lbs : Minimum fuel in each wing for takeoff or intentional go around.
760 lbs. or less : Max Tip Tank quantity before initiating transfer.
925 lbs : Max Tip tank quantity for landing
13,500 lbs : Maximum Zero . Wing and Tip Fuel Weight
What does the Delta Fin on an extended range tank 35 do?
lateral stability, as well as preventing a deep stall
Do the pumps push or pull fuel?
Push
What is the rate of the standby pumps?
50 lbs. / min
100 lbs. / net change
Formula to Calculate Vref:
105 – basic starting
+1/2 fuel
+ 1 knot per passenger
+1 knot per 100 lbs
4000 lbs
105 + 20 + 1 pax = 126
Rule of thumb Fuel Technique
1st Hour
2nd Hour
every consecutive hour after
1500 – 1st Hour
1300 – 2nd Hour
1100 – every consecutive hour after
High pressure stage pump uses
Motive flow (regulated to 300 PSI)
Jet pump send fuel
directly to inboard wing
Less than .25 psi the
Low-pressure fuel switch activates and low-pressure fuel light will illuminate. Indicates whether motive flow is working or not, hence the low number. It either is or it isn’t.
Standby Pump average PSI
18-21
when fuel filter is being bypassed you get the FUEL FILTER light. This fuel filter is located
in the tailicone.
Engine fuel filters are being bypassed
the pin on the nacelle.
Fuel SOV is located
in the tail cone
Standby pump and Fuselage pump are cooled by
The fuel they sit in
White empty light indicates fuel pressure in transfer line is less than
2.75PSI.
