Hydraulics Flashcards
- What’s the purpose of Power Transfer Unit?
Provides operational redundancy to left system (especially to get gear up with failure of left engine on takeoff).
- What’s the purpose of Aux pump?
Primarily designed for ground and maintenance operations.
- Where are hydraulic reservoirs located?
There are two (2) hydraulic reservoirs located in forward section of tail compartment: left hydraulic system reservoir on left and right hydraulic system reservoir on right.
- A visual sight gage is installed on high pressure end of each hydraulic reservoir and clearly indicates proper FULL and REFILL levels of reservoir. What is required for accurate reading?
Electrical power is not required to read sight gage; however, system must be pressurized to obtain correct reading.
- Describe engine-driven pump.
It’s constant pressure, variable volume pump, which means it produces 3000 psi anytime engine is running (except for pump unloading feature during engine start in-flight).
- What’s the purpose of hydraulic heat exchangers and where are they located?
There are two hydraulic heat exchangers: one for each system located in each hopper close to floor. Functioning as a radiator, heat exchanger allows 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 precharge on preflight.
- What are requirements for PTU operation when ARMED?
1) Left system pressure < 2400 psi
2) Fluid in left system
3) Right system not hot
- How would gear and flaps operate differently with aux pump?
They’d operate much slower due to low flow rate.
- What are the requirements for Aux pump operation when ARMED?
In-flight:
1) Left system pressure < 1500 psi
2) Fluid in 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.
Aux pump activates on ground with left system and inboard accumulator pressure < 1500 psi and brake pedals depressed. It deactivates when inboard brake accumulator is replenished
- How does Aux pump operate differently in 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.
- There are two replenishing systems in tail compartment. What are they for?
One is for hydraulics and one is for oil replenishing.
