HYDRAULIC M11.11 Flashcards
How is accidental deployment of the RAT prevented on the ground?
By inserting a mechanical safety device
What is a hydraulic demand pump?
A unit that operates when hydraulic demand is greater than the main system pressurisation can cope with (PTU)
Where can fixed displacement hydraulic pumps be found on modern aircraft?
On hydraulic service panels and to open cargo doors
How is it possible to depressurise a hydraulic reservoir for maintenance?
By opening the depressurisation valve on the reservoir
Some of the hydraulic fluid from the pump is used for cooling and lubrication of the pump itself. Where does this cooling fluid go afterwards?
It goes to the case drain
Which of the following components of a multi-plunger hydraulic pump does not rotate when the pump is running?
The wobble plate (or Yoke)
Why are hydraulic reservoirs pressurised?
To prevent cavitation of the main system pumps
What are back up rings in hydraulic components made of?
Teflon or nylon
How does the reservoir ensure a constant fluid supply at different flight altitudes and accelerations?
By the use of sheet metal baffles in the reservoir
How is the output of a variable displacement pump varied?
By changing the stroke of the pistons
What are the safety concerns associated with synthetic fluids?
The fluid should be kept away from plastic components and contact with skin and eyes should be avoided
Some hydraulic pumps are driven by hydraulic motors. How are these motors kept cool during operation?
By hydraulic fluid
Which of the following is most likely to provide an aircraft’s main hydraulic pressurisation?
Engine Driven Pumps
Is it possible to mix different types of hydraulic fluid together?
Synthetic oils can be mixed together, but not with mineral oils
What is a static hydraulic seal?
A seal that is designed to withstand steady or pulsating pressure loads
How can the contents of the hydraulic reservoir be verified?
On ECAM/EICAS and a direct reading gauge on the reservoir
What is the purpose of the hydraulic Power Transfer Unit (PTU)?
To transfer power from one system to another by using a pump
How does the reservoir ensure a constant fluid supply at different flight altitudes and accelerations?
By the use of sheet metal baffles in the reservoir
How is an air driven hydraulic pump powered?
Via a gearbox by pneumatic system air
What is the purpose of the hydraulic accumulator?
To smooth out pressure fluctuations in the system and to provide an instant source of hydraulic pressure
What is the main disadvantage of synthetic hydraulic fluids when compared to mineral oils?
Synthetic fluids absorb water
