Flight Controls and Hydraulics Flashcards
What connects the cyclic and collective controls to the control servos?
A series of pushrods and torque tubes.
What connects the yaw pedals to the tail rotor control bell crank?
A series of cables and pulleys.
How many hydraulic servos are there?
Three.
Which controls are hydraulically boosted?
The cyclic and collective only.
What does the yellow DUAL FLY caption mean?
Both left and right collective throttle switches are in the FLY position.
What is the procedure for handing and taking over control with the throttle switch?
LHS: “You have control.”
RHS: “I have control, going to fly. DUAL FLY caption on.”
LHS: “You have control, going to idle. DUAL FLY caption off.”
The drive for the hydraulic pump also drives which other service?
The transmission oil pump.
If power to the hydraulic solenoid valve fails, to what position will the valve move?
Hydraulics ON.
Relative to the main gearbox, where is the hydraulic filter pop-up?
Left of the main gearbox on the hydraulic pressure filter.
During walk-around, a red pop-up is visible on a metal ‘T’-shaped block on the left side of the main gearbox. What does this indicate?
- The hydraulic pressure filter may be clogged.
- Engineering advice should be sought.
- The aircraft should not be flown.
What two elements within the system are present to prevent excessive hydraulic pressure from causing damage?
- Pressure relief valve.
- Rupture disc.
What is the purpose of the rupture disc in the hydraulic system?
To protect system integrity when fluid pressure exceeds the capability of the relief valve to regulate.
What does HRFM stand for in the hydraulic system?
Hydraulic Reservoir Filter Module.
What is the purpose of the HRFM?
To provide pressure-regulated and filtered hydraulic fluid from the pump to the servo-actuators.
**What are three possible indications of a hydraulic failure?
- Grinding or howling noise from the pump.
- Feedback forces during flight control movement.
- Increase in forces required to move flight controls.
**What are the indications of a flight control actuator malfunction?
- High control forces in one axis only.
- Uncommanded flight control movement.
- Feedback forces only in affected flight control axis.
- Flight control forces normal in unaffected axes.
Where is the hydraulic level sight glass?
On the right hand side of the hydraulic fluid reservoir.
What is the effect on hydraulic pressure if the rupture disc bursts?
All hydraulic pressure will be lost.
What is the impact of a total electrical system failure on the hydraulic system?
Hydraulics continue to function as normal, but cannot be isolated
Where are the hydraulic actuators?
In a support assembly forward of the main gearbox
During the hydraulic system functional check, what four things might indicate a hydraulic malfunction?
Unequal forces
Unusual forces
Control binding
Control motoring
How is the hydraulic fluid cooled?
Cooling fins on the return line from the servos to the HRFM
When might control feedback be felt during the hydraulic checks under normal conditions and what should be done?
- After a cold start
- Cycle the controls with hydraulics ON to warm the system
- Repeat the check
