Hydraulics Flashcards
what are the 3 system colours
Green, Blue, Yellow
what are the normal operating pressures of each hydraulic system (RAT)
3000psi (2500psi on the RAT)
what pumps are used to pressurize the green hydraulic system
ENG 1 driven pump
what pumps are used to pressurize the blue hydraulic system
- electric pump
- RAT driven pump
what pumps are used to pressurize the yellow hydraulic system
- ENG 2 driven pump
- electric pump (when no engine is running)
- hand pump (when no electrics available in the system for operating the cargo doors)
what 2 systems are integrated into the Power Transfer Uint (PTU)
Green and Yellow
when does the PTU operate automatically
if diff pressure between the green and yellow systems > 500psi
how is the RAT deployed
- Auto = AC BUS 1+2 fail and speed > 100kt
- Man = MAN RAT Pb pressed on the OVHD panel
what is the purpose of system accumulators
helps maintain a constant pressure by covering transient demands during normal operations
what is the purpose of the priority valves
cuts off hydraulic power to heavy load users if hydraulic pressure in a system gets low
how are the fire shutoff valves operated
ENG FIRE Pb on the OVHD panel
what are the leak measurement valves located in the hydraulic system
upstream of the primary flight controls
where are hydraulic filters found in the hydraulic system
- HP filters: each system, reservoir filling system, normal braking system
- return line filters on each line
- case drain filters on engine pumps and the blue electric pump
how are the reservoirs pressurized
- HP bleed air from ENG 1
- if bleed air is too low, the system takes bleed air pressure from the XBLEED duct.
what is the purpose of pressurizing the hydraulic reservoirs
prevents cavitation of the pumps
what does the green hydraulic system control
- normal brakes
- rev ENG 1
Priority Valve: - slats and flaps
- landing gear
- NWS (YUD only)
what does the blue hydraulic system control
Priority Valve:
- slats
- EMER GEN
what does the yellow hydraulic system control
- ALT/parking brake
- rev ENG 2
- NWS
Priority Valve: - flaps
what does an amber fault light on the ENG 1 (2) PUMP Pb mean
- reservoir level is low
- reservoir overheats
- reservoir air pressure is low
- pump pressure is low (inhibited on the ground , when engine is stopped)
The light goes out, when the crew selects OFF, except during an overheat (light stays on as long as the overheats lasts)
what does an amber fault light on the BLUE ELEC PUMP Pb mean
- reservoir level is low
- reservoir overheats
- reservoir air pressure is low
- pump pressure is low (inhibited on the ground , when engine is stopped)
- pump overheats
The light goes out, when the crew selects OFF, except during an overheat (light stays on as long as the overheats lasts)
with the BLUE ELEC PUMP Pb in the AUTO position when will it run
provided AC power is available and:
- in flight
- on the ground: 1 engine is running or the BLUE PUMP OVRD PB on the MAINT PNL is pressed
what does an amber fault light on the YELLOW ELEC PUMP Pb sw (springloaded) mean
- reservoir level is low
- reservoir overheats
- reservoir air pressure is low
- pump pressure is low
- pump overheats
The light goes out, when the crew selects OFF, except during an overheat (light stays on as long as the overheats lasts)
when does the yellow electric pump automatically turn on and what effect does it have on the system
- turns on automatically when a crewman selects the cargo door manual selector valve to OPEN or CLOSE
- inhibits the operation of other yellow system functions (except ALT BRAKE and ENG 2 REV)
when is the PTU inhibited
during the 1st engine start
