Fuel Flashcards
System
Crashworthy, suction type with self sealing main tank
Can pressure/gravity/in-flight refuel
Supply Operation
Prime/boost pump primes all lines if prime is lost and acts as boost pump for APU start and operation
Fuel selector valves permit engine operation from either cell
All lines include self-sealing breakaway valves that stop flow if damaged
Tank > eng driven boost pump > fuel filter (can bypass; not sensitive to water) > HMU high pressure pump > oil heat exchanger > ODV > injectors
Fuel Priming System
APU BOOST opens APU shutoff valve and activates prime/boost pump
FUEL PRIME opens both engine prime shutoff valves and allows individual priming of engines with PCL in LOCKOUT
Main Fuel Tank
Two interconnected cells (270-600 lbs per side), lower 1/3 is self-sealing
Capacity is 590 usable gallons (4,012 lbs JP-5)
Left cell: provisions for single-point refuel/defuel, gravity refuel, and HIFR; two high-level shutoff floats, check valve, sump drain and vent
Right cell: two check valves, sump drain, vent, APU fuel line, and fuel dump system
External Fuel Tanks
Ballistically hardened 120 or 113-gallon capacity
Self sealing breakaway valves; jettisonable
Quantity monitored by single probe; contains low-level thermistor sensor exposed when tank is empty
Overflow thermistor at top sends signal if wet
PUMP/VALVE FAIL
Single valve and pump functions during automatic fuel transfer mode; alternates with each activation
= single pump failure, alternate supplies fuel
AUTO FUEL XFER FAULT
Total failure of dual transfer/shutoff valves, dual transfer pumps or FMCP logic
Manual mode must be used if automatic mode fails
External Tank Transfer System
Two transfer/dump pumps transfer fuel until fuel level reaches high-level shutoff valves (can secure manually also)
- CAUTION* During transfer of aux fuel, if right cell fills faster than left cell, monitor fuel quantity gauges closely. If difference persists, stop transferring fuel before right cell is full (approximately 1700 lbs)
- CAUTION* Do not initiate unmonitored manual transfer to the main tank from aux tanks until main tank is below 3,200 lbs. Float valves should prevent overflow of main tank.
Manual Fuel Transfer Check
Check system when main tank has decreased approximately 300 lbs
One manual transfer exercises both pumps and transfer valves to ensure proper operation
External Tank Jettison
NOTE Emergency jettison of external fuel tanks via the ALL STORES JETT pushbutton in inhibited when less than 40 gallons (approximately 272 lbs) remain in the tank. The fuel gauge for external tanks reads in 50lb increments.
Fuel Management Control Panel (FMCP)
Power on refuel: sequencing logic turns off all FMCP switches except precheck
All external tank shutoff valves close until main tank is filled and then open (right then left)
AUTO fuel transfer initiated at 2,640 lbs
Fuel transfer in opposite order of fill (left then right)
PRECHECK Switches
Center provides power to precheck valves in main tank
When moved to A or B, precheck valve interrupted, fuel flow stops and FMCP flow lights go out
NOTE Malfunctioning FMCP with power applied can cause activation of precheck valves, preventing pressure refuel or HIFR. FUEL MGMT c/b must be pulled
Quantity System
1/2 FUEL LOW when cell reaches 300 lbs
Capacitance type sensors employing fuel as a dielectric to measure weight of the fuel in each tank
Green, 10 lb increments
When total fuel <600 lbs, total display turns yellow
Fuel Dump
Min 800 lbs/min
Both transfer/dump pumps energize; dumps fuel from right cell down to low level sensor
With FMCP MASTER and MODE switches set to TRANSFER and MANUAL OVRD, selecting FUEL DUMP allows fuel to dump from external tanks
NOTE Fuel can be dumped while the helicopter is on the ground
Refueling
Gravity: in any order
Pressure: 55psi with or without electrical power (power on in order)
