Questions tagged [hydraulic-system]

Hydraulic systems on aircraft use pressurized liquid to move components such as control surfaces and landing gear.

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4answers
14k views

What triggers the PTU (Power Transfer Unit)?

As highlighted by this answer and by this page the PTU (power transfer unit) is an hydraulic driven pump. It gets energy from one hydraulic system and uses it to pressurize another hydraulic system. ...
15
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6answers
4k views

Why do most commercial airplanes use hydraulics instead of electric/servo motors?

I'm sure it's possible to use servo motors to get precise control of the ailerons, elevators or the rudder. But still, hydraulics are widely used instead. Hydraulics do have a disadvantage that a ...
7
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3answers
2k views

Is is possible to use non-hydraulic fluids in a hydraulic system in an emergency?

In this answer, Ralph wrote: Spare fluid is common enough to have on-board to replenish the resevoirs. After reading that, I recalled an incident I was told ...
13
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3answers
3k views

Do jackscrews suffer from blowdown?

With hydraulic control surfaces, at high airspeeds, there is a point where aerodynamic loads exceed the capability of the actuators. This limits control authority and can result in the control surface ...
2
votes
4answers
10k views

What is the difference between MIL-H-5606 and MIL-PRF-5606 hydraulic fluid?

what is the meaning of PRF here and can you differentiate them visually ?
1
vote
2answers
456 views

What is the average aerodynamic load on a control surface of a commuter-sized airplane?

I'm doing a study about aircraft hydraulic pump sizing. In order to do that, I need to know the size of a flight control actuator, then determine the maximum flow and pressure that the actuator needs. ...