Hydraulics Flashcards
Purpose of the hydraulic system
Provides pressurized fluid to operate all flight control servo actuators to reduce pilot workload
Describe the operation of the hydraulic switch
The switch electrically controls the system
Fail Safe - ON: in case of total electrical failure
ON - solenoid valve de-energized open = pressurized hydraulic fluid flows to the 4 servos
OFF - solenoid valve energized closed = pressurized hydraulic fluid flows to the reservoir and bypasses the 4 servos
Describe the relationship between the switch and the circuit breaker
Circuit breaker protects the electrical circuit that the switch is on.
Switch - OFF
Circuit Breaker - OUT
Hydraulic fluid flows to the servos
What are the components of the hydraulic system?
Reservoir Pump Filters Solenoid valve Relief valve Cyclic and collective servo actuators and supports Tail rotor servo actuator
Describe the hydraulic cooling system
No specific cooling system
- Heat dissipates from the hoses and lines as air circulates beneath forward cowling
Describe the hydraulic reservoir
Reservoir and cover are magnesium alloy
- mounted on brace and support
- site glass must not have any bubbles
Capacity: 1.3 US Pints
Total system capacity: 1.68 US Quarts
Capacity of the Hydraulic Reservoir
1.3 US Pints
Capacity of the Hydraulic System
1.68 US Quarts
What type pump does the hydraulic system use?
Pump is a constant pressure, variable delivery, self-lubricating type
Describe the pump system
Pump is a constant pressure, variable delivery, self-lubricating type
- designed to operate continuously and provide rated discharge pressure of 1000 +/- 25 PSI
- mounted on transmission
- driven by transmission accessory drive
How many filters does the system have?
2
When do the Hydraulic Filter LRBs pop?
70 +/- 10 PSID
At what temp do the hydraulic filter LRBs not work?
Indicators wont work with fluid temp < 2C
- to prevent inaccurate indications
Which hydraulic filter has bypass capability?
Only the return line filter has bypass capability (interior filter)
- to prevent over pressurization of return system
Describe the filters
2 filters, one on pressure line and one on return line, both with impending bypass indicators
- LRB pops at 70 +/- 10 PSID
- Indicators wont work with fluid temp < 2C to precent inaccurate indications
- Only the return line has bypass capability (interior filter) to prevent over pressurization of return system
What is the purpose of the solenoid valve?
Opens or closes the flow of hydraulic fluid to the servos based on the position of the hydraulic switch, or the state of the electrical system
Fail Safe - ON: in case of total electrical failure
ON - solenoid valve de-energized open = pressurized hydraulic fluid flows to the 4 servos
OFF - solenoid valve energized closed = pressurized hydraulic fluid flows to the reservoir and bypasses the 4 servos
Where is the solenoid located and what does it look like?
Mounted on cabin roof, left side of servos
- dark gray tube closest to deck floor
What is the purpose of the relief valve?
Relief valve opens to protect the system from damage.
Where is the relief valve and what does it look like?
Mounted on cabin roof, left of servos
- light grey tube, long and slender
What is the state of the relief valve during normal operations?
During normal operations: relief valve is closed
At what pressures does the relief valve open?
1075 - 1375 PSID
Describe the operation of the relief valve?
When the system pressure rises to within a range of 1075 - 1375 PSID the relief valve opens to protect the system from damage
- returns excess fluid to reservoir
- closes when pressure returns to normal
Which are the cyclic servos
The 2 outboard servos
Which is the collective servo
The single center servo
How are the cyclic and collective servos supported?
Springs installed parallel to push/pull tubes
- assist pilot with increased control feedback forces if hydraulic pressure is lost
Where is the tail rotor servo located?
Intermediate section
- above the baggage compartment
