Fuel Flashcards
Fuel
Appearance of FUEL 1 PRESS LOW and FUEL 2 PRESS LOW during starting indicates either an air leak OR a broken engine driven fuel pump shaft
Fuel pressure light on is an emergency
APU gets its fuel from the #1 tank only
Most dangerous levers in the aircraft are the fuel levers because there is no safety stopping you from putting a direct line into cross-feed (or engine driven boost pump). Takes 5 seconds to flame out an engine
APU burns 120lbs per hour of fuel
JP4 good for cold weather (less efficient tho)
If ignition is off during starting, stop the start and drain the engine of fuel first.
Fuel indicator on MFD ONLY displays what is in the main 2 tanks (Caps)
172lbs total per tank is the fuel low caution
MFD - weight displayed per tank!
Failure to remove contaminants in fuel can cause loss of power and/or engine flame-out
Each tank has an electrically operated submerged fuel boost pump.
Self sealing fuel sell… activates with fuel into a gel and seals the engine
Boost pumps must be operating above 5000’ PA and
Fuel
- primary - JP8
- standard - JP5
- alternative(cold weather) - JP4
Three methods of refuel
- gravity (open port hot gas gravity is mission approved) [two caps, 160 gallons per side]
- pressure (359 gal capacity, one nozzle opening)
- closed circuit [small port, 356 gal capacity]
Normal tanks - 2400lb capacity, approx 2.2 hours of flight time
Four CEFS tanks (two per side) way 5360lbs full
Internal auxiliary tanks - less drag, provide better airspeed
(POINT GUNS DOWN AND OUT)
Fuel Lines
- self sealing (engine only)
- steel braided
Pumps
- submerged boost (pilot controlled)
- prime boost (pilot controlled)
- CEFS (pilot controlled)
- Engine driven
- HMU
Total flight time with full tanks and CEFS - approx 8 hours
Fuel selectors (upper console)
Aux fuel management panel - for external tanks. Must have battery power to open tanks for refueling
XFD - crossfeed
More fuel
Fuel cell will seal holes up to 7.62 rounds (mechanical chemical)
Pressure refuel/defuel valve - high level and low level
If fuel is observed flowing from vent, discontinue refueling
Fuel quantity probe senses the fuel level by electrifying the fuel and sending the data to the MFD. If electrical power is lost, we lose fuel reading
Fuel sample guide tube allows you to check the fuel (5ft long, 4ft tank)
Proper fuel settling time is 4 hours. We check before the first flight of the day, after adequate wait time after cold refuel, or if the fuel sourc is suspected to be contaminated
Check valve - only allows one way direction for fuel, keeps fuel lines primed.
Fuel tanks have breakaway valves for post-crash fire prevention. Valves held open when attached to tank
Commercial fuels are toxic to humans and animals - we put PRIST inside the fuel to stop algae from growing in our fuel…
- Engine anti-ice/heater switches - burns an extra 100lb per hour
- Cockpit/gunner heater on - about 20lb/hr
Closed circuit
- max hose pressure 15PSI, 110GPM
Pressure
- max 55PSI, 300GPM
Pressure de-fueling
- can do it, always have some residual fuel left and will require someone opening the bottom vent to finish draining the fuel
Self sealing fuel lines are the black rubbery ones, APU and CEF fuel lines are NOT self sealing
APU pump is located on top of the tanks in the middle, only uses tank #1
CEF Pump is also up in the top of the tanks.
If we smell fuel, it is VERY bad
Engine driven boost pump sucks fuel from the cross-feed during start, its shaft can break and is why we start the engines this way (to test)
Brain of electronic limiting is the DEC, mechanical limiting and fuel governed by the HMU
Large vent valves let air out when we refuel
Fuel selector is in the oil cooler compartment
Fuel cautions in center, cautions on the right, advisories on the left
“FUEL 1 BYPASS” - fuel filter bypass (word filter is omitted due to length)
Fuel pressure has no gauge, but low pressure is an emergency
Fuel XFER fail - external
PRIME BOOST PUMP ON - APU boost pump is on
3 dashes on a fuel number is an INPUT FAILURE
FUEL LOW light comes on when fuel goes below the white line
Fuel test indicator - usually a maintenance function. Numbers will change when pressing, will return to original value when un-pressed
NG section turns the accessory section of the engine
BYPASS light comes on when a filter bypass happens… not FILTER
3 main inputs to HMU to affect fuel - LDS, PCL, PAS and DEC through torque motor
Fuel filter bypass - BYPASS
NP overspeed, ODV shuts off fuel above 120%
APU Fuel System
Prime Boost Pump is APU pump
DESU/ESU box controls operation of the APU
EPs
FUEL 2 BYPASS - go to CROSSFEED on that side’s fuel lever
Both FUEL 1/2 BYPASS - land as soon as possible
when in doubt, land and somewhere that fuel can reach you!
FUEL PRESS LOW - go to crossfeed (XFD), land as soon as possible (leak could cause a fire)
engine driven pumps run always
