Systems Flashcards
Describe the fuel system
3 interconnected crash resistant fuel cells. 2 forward cells under forward passenger seats, 1 aft cell under/behind aft passenger seat. Fuel from forward cells transferred to aft cell via dual element injector pump (located between forward cells).
- Two boost pumps located in sump of aft cell.
- 2 fuel quantity probes: one in left forward cell, one in aft cell.
o If boost pump fails or clog in line, flow switches activate the L FUEL PUMP or R FUEL PUMP caution light. 160 lbs unusable.
- Low fuel switch in aft cell – if this is activated, LOW FUEL caution light (50-75 lbs usable left).
- Fuel sump equipped with electric solenoid drain valve (for fuel drains).
- Left fuel boost pump directly wired into battery.
- Fuel gauge shows quantity of usable fuel left (full fuel = 669.1 lbs)
Describe the hydraulic system
Reservoir, pump, solenoid valve, 2 filter modules, pressure relief valve, 3 servo actuators (2 cyclic and 1 collective)
- Hydraulic pump mounted on and powered by transmission through rotor tachometer generator. Pump is variable delivery and self-lubricating to provide discharge pressure of 600 ±25 PSI.
- Fluid supplied to pump via vented gravity feed reservoir mounted forward of transmission. Fluid passes through pup, pressure filter, relief valve, and solenoid valve.
o Solenoid valve is operated by HYDRAULIC SYSTEM switch. When ON solenoid valve is deenergized to open position (fluid routed to actuators). From actuators, fluid returns to the return filter and reservoir.
o Relief valve is normally closed but will open when 670-770 PSI to control pressure and protect system from damage
Describe the pitot static system
pitot tube, right and left static ports, airspeed indicator, altimeter, tubing/hardware between components
Describe the electrical system
How is external power used?
When can BATT be used if using external power?
28V DC electrical system. Power obtained from 24V (17Ah) Ni-Cd battery and 30V 200A starter/generator
Battery, starter-generator, voltage regulator, relays, 28V DC bus, circuit breakers.
- All circuits are single wire with fuselage common ground return
- Negative terminals of starter-generator and battery are grounded to helicopter structure.
- Generator has over voltage protection set at 31±1V. When limit is exceeded, voltage regulator will disconnect the starter-generator from the system. Generator failure indicated by GEN FAIL caution light and zero load meter reading.
- Battery can supply emergency DC load for ~1 hr with a 17A drain.
External Power – APU capable of delivering 28V DC with 400A rating is required.
Battery Switch – BATT switch can be turned on after external power is applied. In ON position, battery charging is supplied by external power and must be monitored.
- If BATT HOT illuminates, turn BATT off.
o If BATT is OFF and BATTERY RLY caution light comes on, indicates battery relay has failed to open (i.e. battery will continue to receive charge from generator). To prevent this, turn GEN off.
o To reduce load on overheated battery, pull non-essential circuit breakers. Do not pull LEFT BOOST, it is essential.
- In normal flying condition, BATT is charged by the generator
Describe audio warning system
ROTOR RPM and ENG OUT audio warnings emitted from cabin horns aft and left of overhead console. Some helicopters may be equipped with a warning horn mute button.
- ROTOR RPM LOW audio – steady sound. Activates when N2 < 90%. Stops when collective is down on stop.
- ENG OUT audio – intermittent sound. Activates when N1 < 55%.
