Single Hydraulic Flashcards
(31 cards)
Components of the system
1 belt driven hydraulic pump
1 hydraulic unit/distributor
1 hydraulic fluid reservoir
4 hydraulic servos (3 MR w/ nitrogen accumulators and 1 TR w/ yaw load compensator)
Hydraulic switches and lights
Describe the hydraulic pump
Single belt driven hydraulic pump off the main drive line on the right side of the MGB
Constant flow and rate
40 bar pressure
Describe the hydraulic distributor
3 Micron filter w/ clog indicator
Pressure sensor
Pressure regulator 43 +/- 1 bar
Solenoid for HYD TEST button
Located on the right side of the MGB
When does the Pressure Switch close?
< 30bar +/- 5 bar
When does the clogging indicator pop?
2.7bar differential pressure
Volume of the reservoir
2.1 liters
Whats the purpose of the MR servo nitrogen accumulators?
Provide small energy reserve giving the pilot time to reconfigure the aircraft to safe operating speeds
What are the two types of servo actuator options?
Samm
Dunlop
Whats the difference between the Samm and Dunlop servo actuators?
The Dunlop incorporates a system to eliminate the input lever play in case of loss of hydraulic pressure
Taking up the input play improves control in manual mode
How do the MR accumulators work?
System pressure drops - accumulators release stored pressure as nitrogen expands.
The non-return valves close and the servo actuators are kept pressurized until the accumulators are fully discharged.
Describe state of the nitrogen bladders in the accumulators in normal operation and in pressure loss state.
Normal operation: bladders are compressed by hydraulic pressure
Pressure loss: bladders expand, pushing fluid into actuators so pilot can get to safe speeds
Purpose of the Yaw Load Compensator
Assists the pilot with TR Control during a loss of hydraulic pressure
- favors right pedal
- depressurized using the “ACCU TST” button for emergency situations or post-flight procedures
Degree range of the TR when moving pedal stop to stop
-8deg to +23deg
What are the two TR systems that aid the pilot in a loss of hydraulic pressure?
- Boss weights
- Yaw load compensator
Normal operation of the TR hydraulic system
Hydraulic system charges an accumulator (compensate for loads in pressure loss state) and an actuator (compensate for loads in a pressure state)
How is the accumulator kept charged in a pressure loss state?
- non-return valve in the pressure circuit
- pressure relief valve set to 55bar
- solenoid valve always closed and opened by the pilot
Forces equal to servo pitch return force under normal op.
Total force = applied by pilot + applied by servo actuator = zero pitch return force
How does the clog indicator work?
Normal op - Spring keeps the magnetic piston pressed against the clog indicator.
Clog - increased hyd fluid pressure causes fluid to flow around magnetic piston. Fluid pressure pushes piston in, overpowering the spring. Relieved of magnetic pressure, a separate spring pushes the indicator out.
At what pressure does the HYD light come on?
< 30bar pressure
Function of the HYD TEST or ACCU TEST button
Opens to route the servo actuator supply back to the reservoir, depressurizing the system, allows backup accumulators to be tested on servo actuators.
Function of the HYD Cutoff switch
Located on collective lever
Used for loss of hyd pressure or seizure of servo actuator distributor
- routes the servo pressure back to reservoir
- eliminates back pressure in manual control, reducing control loads
When do you check for proper pressure of the Yaw Load Compensator?
On shutdown
What are the two functions of the Horn?
- Nr <306 RPM
- Loss of Hydraulic pressure
Purpose of the Hydraulic Accumulator Check
To ensure the accumulators provide pitch/roll assistance
