Hydraulics Flashcards
What’s the purpose of the Power Transfer Unit?
It provides operational redundancy to the
left system (especially to get the gear up with failure of the left engine on takeoff).It’s part of both primary hydraulic systems and, when activated, can power the flaps, landing gear, inboard brakes and parking brakes, cabin door, and nose wheel steering.
What’s the purpose of the Aux pump?
It’s primarily designed for ground and maintenance operations. It’s part of the left hydraulic system and, when activated, can power the flaps, landing gear, inboard brakes and inboard parking brake, cabin door, and nose wheel steering.
Where are the hydraulic reservoirs located?
There are two (2) hydraulic reservoirs located in the forward section of the tail compartment (left hydraulic system reservoir on the left and right hydraulic system reservoir on the right).
A visual sight gage is installed on the high pressure end of each hydraulic reservoir and clearly indicates the proper FULL and REFILL levels of the reservoir. What is required for an accurate reading?
Electrical power is not required to read the sight gage; however, the system must be pressurized to obtain a correct reading.
Describe the engine-driven pump.
It’s a constant pressure, variable volume pump, which means it produces 3000 psi anytime the engine is running (except for a pump unloading feature during engine start in-flight).
What’s the purpose of the main hydraulic system filters and what indication would you get for an impending blockage?
They provide hydraulic system components with filtered fluid. You get a CAS message for impending blockage.
What’s the purpose of the hydraulic heat exchangers and where are they located?
There are two hydraulic heat exchangers:one for each system located in each hopper close to the floor. Functioning as a radiator, the heat exchanger allows the surrounding, cooler fuel to cool the hotter hydraulic fluid.
How many hydraulic accumulators are there and what’s the pre-flight requirement?
There are two accumulators: one for each system. Check for 1200 psi at 70°F nitrogen pre-charge on preflight.
The PTU’s bearing wear indicator will pop to indicate excessive motor bearing wear. What’s the required action if it’s discovered popped on preflight?
Reset and note time in log book.
Continued operation for the next 50 flight hours is allowed; however, you need to check it prior to each flight.
What are the requirements for PTU operation once it’s been ARMED?
1) left system pressure < 2400 psi
2) fluid in the left system >0.36 gallons
3) right system fluid not hot <107°C
How would the gear and flaps operate differently with the aux pump?
They’d operate much slower due to low flow rate
What are the requirements for Aux pump operation once it’s been ARMED?
1) left system pressure < 1500 psi
2) fluid in the left system
3) left system not hot
4) flap handle position doesn’t match flap position OR landing gear handle position doesn’t match gear position
How does the Aux pump operate differently in the air when selected to ON?
It operates regardless of hydraulic quantity or temperature; however, it automatically shuts off after two (2) minutes to prevent inadvertent depletion of the batteries.
What can be done if the Aux pump shuts off due to overload?
You can cycle the switch and try it again
There are two replenishing systems in the tail compartment. What are they for?
One is for hydraulics and one is for oil replenishing
